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101.
Mihaela Badea Rodica Olar Monica Iliş Rodica Georgescu Mirela Călinescu 《Journal of Thermal Analysis and Calorimetry》2013,111(3):1763-1770
Three new copper (II) complex compounds with chlorhexidine (CHX) as ligand have been prepared and characterized by elemental and thermogravimetrical analyses, molar conductances, infrared, and UV–Vis spectra. Chlorhexidine acts as neutral tetradentate NNNN donor, coordinating through the four imine nitrogen atoms. Based on the experimental data the following formulas have been proposed for the complex compounds: [Cu(CHX)](NO3)2 (1), [Cu2(CHX)Br2Cl2]·4H2O (2), and [Cu(CHX)Cl]Cl (3). Thermal decomposition evidenced dehydration (complex 2), anionic moieties release and the ligand cleavage with chlorobenzene moieties removal for all complexes. The final residue is in all cases copper oxide. Antibacterial and antifungal activities of the complexes have been determined in vitro, by the cup-plate agar diffusion method, against Escherichia coli, Staphyloccocus aureus, and Candida albicans. The complexes present an activity comparable to that of chlorhexidine, the most active being [Cu2(CHX)Br2Cl2]·4H2O. 相似文献
102.
Anca Dumbravă Rodica Olar Mihaela Badea Maria Nicoleta Grecu Florentina Pătrascu Luminita Măruţescu Nicolae Stănică 《Journal of Thermal Analysis and Calorimetry》2014,115(3):2447-2455
New complexes ML(CNS)·nH2O [M = Ni, n = 0.5; M = Cu, n = 4.5; M = Zn, n = 0.5, HL: 6-mercapto-(1,4,8,11-tetraazaundecanyl)-6-carboxylic acid)] have been synthesised, chemical analysed, and characterised by different spectroscopic techniques (IR, UV–Vis–NIR, 1H NMR, EPR, ESI–MS), and magnetic measurements. Based on the IR spectra a dinuclear structure with the 1,3-CSN coordination was proposed for Ni(II) and Cu(II) complexes. The dinuclear structure of Cu(II) complex is also consistent with both magnetic behaviour and EPR spectrum. According to TG, DTG and DTA curves the thermal transformations are complex processes, including dehydration, Mannich base oxidative degradation and thiocyanate decomposition. The final product of decomposition is the most stable metallic oxide, as XRD data indicates. The new complexes were also screened for their microbicidal and antibiofilm properties. 相似文献
103.
We introduce a notion of solution to the wave equation on a suitable class of time-dependent domains and compare it with a previous definition. We prove an existence result for the solution of the Cauchy problem and present some additional conditions which imply uniqueness. 相似文献
104.
105.
106.
Using static oxygen-bomb calorimetry, the standard enthalpies of combustion of the 2,4-and 2,6-isomers of dinitrophenol have been determined as ?2697.22 and ?2723.08 ± 3.18 kJ mole?1, respectively. Standard enthalpies of formation have been calculated as ?235.50 and ?209.64 ± 3.27 kJ mole?1, respectively. 相似文献
107.
We give a precise mathematical formulation of a variational model for the irreversible quasi-static evolution of brittle fractures proposed by G. A. Francfort and J.-J. Marigo, and based on Griffith's theory of crack growth. In the two-dimensional case we prove an existence result for the quasi-static evolution and show that the total energy is an absolutely continuous function of time, although we cannot exclude the possibility that the bulk energy and the surface energy may present some jump discontinuities. This existence result is proved by a time-discretization process, where at each step a global energy minimization is performed, with the constraint that the new crack contains all cracks formed at the previous time steps. This procedure provides an effective way to approximate the continuous time evolution. 相似文献
108.
109.
Mihaela Badea Rodica Olar Dana Marinescu Gina Vasile 《Journal of Thermal Analysis and Calorimetry》2008,92(1):205-208
This paper reports the investigation of the thermal stability of a series of new complexes with mixed ligands of the type
[M(en)(C3H3O2)2]·nH2O ((1) M=Ni, n=2; (2) M=Cu, n=0; (3) M=Zn, n=2; en=ethylenediamine and (C3H3O2)=acrylate anion). The thermal behaviour steps were investigated in a nitrogen flow. The thermal transformations are complex
processes according to TG and DTA curves including dehydration, ethylenediamine elimination as well as acrylate thermolysis.
The final products of decomposition are the most stable metal oxides except for complex (2) that generates metallic copper. 相似文献
110.
Rodica Olar Mihaela Badea Maria Nicoleta Grecu Dana Marinescu Veronica Lazar Carmen Balotescu 《Journal of Thermal Analysis and Calorimetry》2008,92(1):239-243
The N,N-dimethylbiguanide (HDMBG) complexes [Cu2(HDMBG)2Cl4] (1) and respectively [Cu(HDMBG)2]Cl2·2H2O (2) exhibit in vitro antimicrobial activity. The complexes were characterised by IR, electronic as well as EPR spectra. The IR spectra of complexes show the pattern of N,N-dimethylbiguanide coordinated as chelate. The electronic and EPR data are in agreement with a square pyramidal stereochemistry for (1) and a square planar one for (2). The in vitro qualitative and quantitative antimicrobial activity assays showed that the complexes exhibited variable antimicrobial activity against Gram-negative strains (Escherichia coli, Klebsiella spp. and Enterobacter sp.) isolated from the hospital environment. The thermal analysis has evidenced the thermal intervals of stability and also the thermodynamic effects that accompany them. The thermal behaviour in nitrogen is complex according to TG and DTA curves including melting, dehydration as well as compounds decomposition. 相似文献