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To eliminate uncertainties in relative orientation, sometimes it becomes advantageous to include additional information on geometrical structures, which remain invariant under changes in camera calibration and viewing positions. Such structures may be lines, circles, etc. Combined with robust estimation of the orientation parameters, we can substantially reduce the effects of outliers.

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Abstract  

Short survey on the latest developments on standardisation and standard reference materials for particles, surfaces and pore size analysis.

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Abstract  

We investigate the relationship between the geometry of a closed, oriented 3-manifold M and the symplectic structures on S 1 × M. In most cases the existence of a symplectic structure on S 1 × M and Thurstonșs geometrization conjecture imply the existence of a geometric structure on M. This observation together with the existence of geometric structures on most 3-manifolds which fiber over the circle suggests a different approach to the problem of finding a fibration of a 3-manifold over the circle in case its product with the circle admits a symplectic structure.

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Abstract  

In order to obtain a better understanding of the pyrolysis mechanism of urazole, molecular orbital (MO) calculations and evolved gas analysis were carried out. The MO calculations were performed using the density functional method (B3LYP) at the 6-311++G(d,p) levels by Gaussian 03. The geometrical structure of urazole and its tautomers were examined theoretically. Identification and real-time analysis of the gases evolved from urazole were carried out with thermogravimetry-infrared spectroscopy (TG-IR) and thermogravimetry-mass spectrometry (TG-MS). The evolved gases were identified as HNCO, N2, NH3, CO2, and N2O at 400 °C, but were different at other temperatures.

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Abstract  

Thermokinetic parameters of the solid-state of poly(o-toluidine) (POT) doped with perchloric (HClO4) acid was studied by thermogravimetric analysis (TG) and differential thermal analysis (DTA) under non-isothermal conditions. Molecular mechanics (MM) calculations suggest that the optimal geometric structure (OMG) of the HClO4-doped POT is at least four orders of magnitude more stable than the molecular geometric (MG) structure. These calculations indicate that the potential energy (PE/kJ mol−1) of the OMG is about four (1.09·104) orders of magnitude lower than the MG structure of the same matrix. The empirical formula of the doped polymer is best represented by [POT-2HClO4·2H2O]n as substantiate by elemental analysis and MM calculations. The full polymer decomposition and degradation were found to occur in three stages during the temperature increase. The decomposition activation energy (E d) of HClO4-doped POT matrix was calculated by employing different approximations. The heating rate (α) of the decomposition and the frequency factor (K o) were calculated. A number of equations were used to evaluate the kinetic parameters. The mechanism of the degradation of the conducting polymer is explained on the basis of their kinetic parameters. A remarkable heating rate dependence of the decomposition rate was observed.

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Abstract  

New metal complexes of Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) with salicylidine-2-aminobenzimidazole (SABI) are synthesized and their physicochemical properties are investigated using elemental and thermal analyses, IR, conductometric, solid reflectance and magnetic susceptibility measurements. The base reacts with these metal ions to give 1:1 (Metal:SABI) complexes; in cases of Fe(III), Co(II), Cu(II), Zn(II) and Cd(II) ions; and 1:2 (Metal:SABI) complexes; in case of Ni(II) ion. The conductance data reveal that Fe(III) complex is 2:1 electrolyte, Co(II) is 1:2 electrolyte, Cu(II), Zn(II) and Cd(II) complexes are 1:1 electrolytes while Ni(II) is non-electrolyte. IR spectra showed that the ligand is coordinated to the metal ions in a terdentate mannar with O, N, N donor sites of the phenloic -OH, azomethine -N and benzimidazole -N3. Magnetic and solid reflectance spectra are used to infer the coordinating capacity of the ligand and the geometrical structure of these complexes. The thermal decomposition of the complexes is studied and indicates that not only the coordinated and/or crystallization water is lost but also that the decomposition of the ligand from the complexes is necessary to interpret the successive mass loss. Different thermodynamic activation parameters are also reported, using Coats-Redfern method.

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Metal complexes of fenoterol drug

Preparation, spectroscopic, thermal, and biological activity characterization

Journal of Thermal Analysis and Calorimetry
Authors:
M. Soliman
,
Gehad Mohamed
, and
Eman Mohamed

Abstract

Metal complexes of fenoterol (FEN) drug are prepared and characterized based on elemental analyses, IR, 1H NMR, magnetic moment, molar conductance, and thermal analyses (TG and DTA) techniques. From the elemental analyses data, the complexes are formed in 1:2 [Metal]:[FEN] ratio and they are proposed to have the general formula [Cu(FEN)2]·2H2O; [M(FEN)2(H2O)2yH2O (where M = Mn(II) (y = 2), Co(II) (y = 4), Ni(II) (y = 4), and Zn(II) (y = 0) and [Cr(FEN)2(H2O)2]Cl·H2O. The molar conductance data reveal that all the metal chelates are non-electrolytes except Cr(III) complex, having 1:1 electrolyte. IR spectra show that FEN is coordinated to the metal ions in a uninegative bidentate manner with ON donor sites of the aliphatic –OH and secondary amine –NH. From the magnetic moment measurements, it is found that the geometrical structures of these complexes are octahedral (Cr(III), Mn(II), Co(II), Ni(II), and Zn(II)) and square planar (Cu(II)). The thermal behavior of these chelates is studied using thermogravimetric and differential thermal analyses (TG and DTA) techniques. The results obtained show that the hydrated complexes lose water molecules of hydration followed immediately by decomposition of the coordinated water and ligand molecules in the successive unseparate steps. The FEN drug, in comparison to its metal complexes is also screened for their antibacterial activity against bacterial species (Bacillus subtilis, Staphylococcus aureus, Escherichia coli, and Salmonella typhi), Yeasts (Candida albicans and Saccharomyces cervisiae), and Fungi (Aspergillus niger and Aspergillus flavus). The activity data show that the metal complexes have antibacterial activity like that of the parent FEN drug against one or more species.

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Thermoanalytical characterization of polyphenylacetylene

II. Comparison of polymers synthesized through metathesis polymerization with different C6H5OH/Mo(CO)6 molar ratios

Journal of Thermal Analysis and Calorimetry
Authors:
A. Luyt
and
H. Vosloo

Abstract  

DSC and TG were used to compare the thermal behaviour of different samples of polyphenylacetylene obtained through the metathesis polymerization of phenylacetylene using different C6H5OH/Mo(CO)6 molar ratios as catalytic systems. In nitrogen the lower molecular mass group of samples give only one exothermic peak below 300°C that is attributed to decomposition to aromatic compounds. The higher molecular mass group of samples give also an exothermic peak shoulder at 239°C, which is explained by crystallization or solid state transition. In oxygen a strong exothermic peak is observed at 223°C, which is not accompanied by mass loss and is attributed to an initiation step of processes taking place at higher temperatures. The higher molecular mass group, however, show much larger transition enthalpies and increased rates of mass loss at the higher temperatures. The difference between the two groups are explained by longer chain lengths and changes in geometrical structure as a result of higher C6H5OH/Mo(CO)6 molar ratios.

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geometric structure Adv. Geom. 3 251 – 261 10.1515/advg.2003.015 . [21] Hamilton , N. Mathon , R

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experiences in detail, frequently describe seeing vivid and detailed geometric structures, experienced synesthesia, visions of alternate worlds, encounters with strange autonomous entities and divine beings, interactions with complex technological objects

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