The mechanism of thermal decomposition of Co(NO3)2 · 2H2O

The mechanism of thermal decomposition of Co(NO₃)₂ · 2H₂O was found to involve stages in which Co(NO₃)₃ and Co₂O₃ · H₂O are formed both of which decompose to Co₃O₄. During the process, the total cobalt enters the +3 oxidation state, which is consistent with the results reported by Mehandjiev [2].

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Zusammenfassung Es wurde gefunden, daß der Zersetzungsmechanismus von Co(NO₃)₂ · 2H₂O Schritte umfaßt, bei denen Co(NO₃)₃ sowie Co₂O₃ · H₂O gebildet werden, beides weiterzerfallend zu Co₃O₄. Während des Vorganges erreicht das Gesamtkobalt die Oxidationsstufe +3, was mit Ergebnissen von Mehandjiev übereinstimmt [2].

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, , CO₃O₄. , .

     

Attractive halogen–halogen interactions: F3CCl⋯FH and F3CCl⋯FCH3 dimers

The F₃CCl?FH and F₃CCl?FCH₃ dimers, which feature the halogen–halogen contacts, are investigated at MP2/6–311++G(d,p) and MP2/aug–cc–pVDZ levels of approximation. The binding energies of these complexes are found to be comparable to those of the weak hydrogen bonds. In both complexes the Cl?F are found to be significantly shorter than the sum of the corresponding van der Waals radii. The C–Cl?F contacts are also found to exhibit certain deviation from linearity. However, the energy differences between linear and bent structures are very small and primarily accounted for by electrostatic interactions between remote parts of the dimer. This indicates a high conformational flexibility of the halogen–halogen contacts and may help to explain the diversity of structural features in crystals formed by halogen-containing molecules. In both dimers the halogen–halogen interaction leads to certain shortening of the C–Cl electron accepting bond. This is accompanied by a small increase of the C–Cl stretching frequency. Hence, the two investigated dimers can possibly be classified as the blue-shifting halogen–halogen contacts.     

Incorporation of Na(+),K(+)-ATP-ase into the thiolipid biomimetic assemblies via the fusion of proteoliposomes

The black lipid membranes (BLMs) are artificial membrane systems that have been widely used in the study of different biological processes. In this paper the planar bilayer lipid membranes have been used to study the behavior of thiolipid molecules-dipalmitoyl-phosphatidyl-ethanolamine-mercaptopropionamide (DPPE-MPA) and cholesteryl 3-mercaptopropionate (Chs-MPA)-as compared to classical BLM made of natural lipids. We present our experiments on black thiolipid bilayer (BTM) formation from a thiolipid solution and basic results of pump currents generated by sodium-potassium pump-Na(+),K(+)-ATP-ase-introduced to such bilayer systems via proteoliposome adsorption with subsequent fusion. Our results imply that no substantial difference exists between BLMs formed from classical lipids and those made from thiolipids used in this study. The same thiolipid molecules were subsequently used for the formation of covalently bound, tethered bilayer lipid membranes (t-BLMs) on polycrystalline gold electrodes. Similarly, as in the case of BLMs, we took advantage of proteoliposome adsorption/fusion to obtain a t-BLM system with reconstituted enzyme. The vesicle fusion on hydrophobic or hydrophilic substrates is one of the main ways to obtain a bilayer system with incorporated biological species. In this paper we present also our preliminary results of electrochemical experiments using rapid solution exchange technique on such t-BLMs systems and their comparison with painted solid supported membranes (SSMs) and BLMs. We have also followed the process of vesicles fusion onto thiolipid monolayer by means of in situ atomic force microscopy in tapping mode (TM-AFM). On the basis of these experiments, we conclude that DPPE-MPA and Chs-MPA molecules used in our experiments preserve lipid properties, allowing for at least partial reconstitution of Na(+),K(+)-ATP-ase into such t-BLMs. On the other hand, the relatively compact organization on polycrystalline gold and the hydrophobic nature of the first monolayer of tethered thiolipids slows down the proteoliposome fusion onto such monolayers and consequently hinders the protein insertion. However, this effect can be overcome by mechanical stimulus that facilitates proteoliposome delamination onto the self-assembled monolayer.     

Spectrophotometric determination of aluminum with bromopyrogallol red in the presence of surfactants

Spectrophotometric methods are described for the determination of microgram amounts of aluminum based on the formation of a ternary complex between the metal, bromopyrogallol red, and cetyltrimethylammonium bromide or nonylphenol tetradecaethylene glycol ether. The complexes have absorbance maxima at 627 and 612 nm, respectively, with molar absorptivities of 5.0 × 10⁴ and 2.2 × 10⁴ liter mol^?1 cm^?1. Numerous metals interfere. Aluminum can be easily separated by extraction of interfering ions with cupferron.     

Stability investigations of laser with saturable absorber

Stability of steady solutions of semiclassical laser-absorber model is investigated. It is found that the solutions exhibit instabilities for all values of cavity losses and, for some values of parameters, additional instability, connected with phase, appears. It is also shown by a numerical calculation that in an unstable region periodic and erratic motion can exist above criticallity.Supported in part by the Polish Ministery of Science, Technology and Higher Education, Project M.R.I.7     

Causal logic of Minkowski space

It is shown that double-orthogonal sets (diamonds) in Minkowski space form an orthomodular complete lattice. Connection with empirical logic of Randall and Foulis is discussed.     

Triplet losses in dye lasers

The expression for losses due to triplet states in dye laser considered as a six-level system is given. It is shown that triplet losses depend on pumping parameters and photon number. Depending on molecular and cavity parameters two different behaviours of dye lasers are expected. Physical conditions are discussed in which triplet losses as well as photon number undergo a jump at the threshold.     

Kinetic parameters from thermogravimetric study of used rubber granulates–polyurethane composites

From the TG data of rubber granulates, different polyurethane and composites it can be seen that the thermal decomposition for the rubber granulate and all of the composites start above 520 K. Two major mass losses for the rubber granulates and majority of the composites were observed and thermal decomposition is essentially complete by ~820 K. The changes of activation energies of lower and higher temperature decomposition, calculated according to the different equations were observed for a priori assumed first-order reaction for devolatilisation. Differences between determined and calculated results could suggest a possible reaction between polyurethane agents and rubber granulate during the composites formations.     

Association equlibria in acetonitrile solution of tetracyanoquinodimethanides

Trimetric ion (TCNQ)^2?₃ has been discovered in mixed solutions of TCNQ and LiTCNQ in acetonitrile. The estimated association constant isK_T = 5.6 × 10¹⁰ øl² mol^?2.     

Enhancement of dielectric and electro-optical parameters of a newly prepared ferroelectric liquid crystal mixture by dispersing nano-sized copper oxide

ABSTRACT

Here, we present the effect of copper (II) oxide nanoparticles (nCuO) on dielectric and electro-optical parameters of a newly prepared ferroelectric liquid crystal (FLC) mixture, namely W302. The FLC mixture, comprising of pyrimidine compounds, was characterised through dielectric spectroscopy, differential scanning calorimetry (DSC), polarising optical microscopy (POM) and other electro-optical methods. The material parameters such as spontaneous polarisation, rotational viscosity, response time and tilt angle of W302 were found to be 14 nC/cm², 240 mPa.s, 150 µs and 28^?, respectively. The phase transition temperatures of W302 were observed through DSC and further confirmed by the dependence of dielectric loss factor in homogeneously aligned FLC sample with temperature. We also demonstrate the observance of a low-frequency dielectric relaxation mode due to the unwinding of the helix, called as partially unwound helical mode (p-UHM) along with Goldstone mode. The behaviour of p-UHM has been systematically studied with temperature and applied bias field. Further, dispersion of nCuO into host W302 has shown a significant increase in dielectric permittivity. Also, the p-UHM relaxation peak in the dielectric regime has disappeared with the incorporation of nCuO. These studies would be useful to fabricate better electro-optical devices for display, switching and beam steering applications. The formulation and characterization of a ferroelectric liquid crystal (FLC) mixture W302 composed of pyrimidine compounds is presented. Then, we observed the effect of copper (II) oxide nanoparticles (nCuO) on dielectric and electro-optical parameters of a newly prepared and characterized FLC mixture.