Spectrophotometric study of the reaction of Co(II) and Ni(II) with nitroso-R-salt and α-nitroso-β-naphthol

The complexes of Co(II) and Ni(II) with nitroso-R-salt are studied by conductometric titration and spectrophotometric methods in buffer solutions of differentpH. The study proved the possible formation of (11), (12) and (13) complexes for Co(II) while Ni(II) forms (11) and (12) complexes (metal:ligand) only. The factors affecting complex formation are established and the formation constants of the complexes are evaluated. The ir spectra of the solid complexes with -nitroso--naphthol revealed that the ligand exhibits the nitrosophenol structure and that the reaction takes place through proton displacement from the OH-group.

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Spektrophotometrische Studie zur Reaktion von Co(II) und Ni(II) mit Nitroso-R-Salz und -Nitroso--naphthol

Zusammenfassung Es wurden die Komplexe von Co(II) und Ni(II) mit Nitroso-R-Salz mittels konduktometrischer und spektrophotometrischer Methoden in Puffer-Lösungen mit verschiedenempH untersucht. Für Co(II) wurden (11)-, (12)- und (13)-Komplexe gefunden, während für Ni(II) lediglich (11)- und (12)-Komplexe (Metall:Ligand) festgestellt werden konnten. Die Faktoren, die die Komplexierung bestimmen, werden diskutiert und die Komplexbildungskonstanten wurden bestimmt. Die IR-Spektren der Komplexe mit -Nitroso--naphthol zeigen, daß der Ligand in der Nitrosophenol-Form vorliegt und daß die Reaktion über eine Protonenverschiebung von der OH-Gruppe verläuft.

     

Polymers as Hydrophobic Adsorbent Surface for Some Surfactants

Polyvinyl alcohol (PVA) and polyacrilic acid (PAA) were used as hydrophobic adsorbent surfaces at 25°C for two nonionic surfactants, namely, tetradecyl polyoxyethylenated monolaurate [La(EO)₁₄] and tetradecyl polyoxyethylenated monooleate [Ol(EO)₁₄], and two anionic surfactants, namely, sodium oleic sulfonate [OlSO₃Na] and sodium dodecyl benzene sulfonate [SDBS]. Surface tension measurements were performed to determine the critical micelle concentration (CMC) and the adsorption isotherms of the tested surfactants. All the tested surfactants display L-shape isotherms except that of OlSO₃Na onto PVA. No adsorption behavior has been shown for the anionic SDBS onto both PVA and PAA. The adsorption data show higher adsorption affinity for all the tested nonionic surfactants onto PAA than onto PVA while the investigated anionic surfactant OlSO₃Na possesses close values of Γ_max. The study reveals that the nature of the polymer surface as adsorbent besides the molecular structure of the surfactant defined the types and mechanisms of adsorption.     

Structural and optical modifications in gamma-irradiated polyimide/silica nanocomposite

The structural and optical properties of thin films of polyimide composites with nanosilica particle content of 15?wt%, prepared via sol–gel process, were studied as a function of the gamma dose. The resultant effect of gamma irradiation on the properties of polyimide/silica nanocomposite has been investigated using X-ray diffraction and UV spectroscopy. Absorption and reflectance spectra were collected by a spectrophotometer giving UV-radiation of wavelength range 200–800?nm. The optical data obtained were analyzed and the calculated values of the optical energy gap exhibited gamma dose dependence. The direct optical energy gap for the nonirradiated polyimide/silica nanocomposite is about 2.41?eV, and increases to a value of 2.65?eV when irradiated with gamma doses up to 300?kGy. It was found that the calculated refractive index of the polyamide/silica increases with the gamma dose in the range 50–300?kGy.     

The collisions of two ion acoustic solitary waves in a magnetized nonextensive plasma

Using the extended Poincaré-Lighthill-Kuo (EPLK) method, the interaction between two ion acoustic solitary waves (IASWs) in a multicomponent magnetized plasma (including Tsallis nonextensive electrons) has been theoretically investigated. The analytical phase shifts of the two solitary waves after interaction are estimated. The proposed model leads to rarefactive solitons only. The effects of colliding angle, ratio of number densities of (positive/negative) ions species to the density of nonextensive electrons, ion-to-electron temperature ratio, mass ratio of the negative-to-positive ions and the electron nonextensive parameter on the phase shifts are investigated numerically. The present results show that these parameters have strong effects on the phase shifts and trajectories of the two IASWs after collision. Evidently, this model is helpful for interpreting the propagation and the oblique collision of IASWs in magnetized multicomponent plasma experiments and space observations.     

Propagation and collision of soliton rings in quantum semiconductor plasmas

The intrinsic localization of electrostatic wave energies in quantum semiconductor plasmas can be described by solitary pulses. The collision properties of these pulses are investigated. In the present study, the fundamental model includes the quantum term, degenerate pressure of the plasma species, and the electron/hole exchange–correlation effects. In cylindrical geometry, using the extended Poincaré–Lighthill–Kuo (PLK) method, the Korteweg–de Vries (KdV) equations and the analytical phase shifts after the collision of two soliton rings are derived. Typical values for GaSb and GaN semiconductors are used to estimate the basic features of soliton rings. It is found that the pulses of GaSb semiconductor carry more energies than the pulses of GaN semiconductor. In addition, the degenerate pressure terms of electrons and holes have strong impact on the phase shift. The present theory may be useful to analyze the collision of localized coherent electrostatic waves in quantum semiconductor plasmas.     

On the linear and nonlinear characteristics of electrostatic solitary waves propagating in magnetized electron-positron-ion plasmas

Both linear and nonlinear propagation of electrostatic solitary waves (ESWs) in magnetized electron-positron-ion (e-p-i) plasmas are analyzed. The electrons and positrons are assumed to be dynamic, whereas positively charged ions are considered stationary. Using the reductive perturbation method, a Zakharov-Kuznetsov (ZK) equation is derived and exact soliton solutions are presented. It is found that both compressive and rarefactive ESWs can propagate. The conditions of transitions from compressive to rarefactive ESWs are specified. The nature of these electrostatic solitary waves structures which depends on the magnetic field, the obliqueness, the ion-to-electron number density ratio, and the positron-to-electron temperature ratio, are discussed.     

Photocatalytic degradation of ciprofloxacin drug in water using ZnO nanoparticles

We report the synthesis of nanostructure ZnO semiconductor with ～2.1 nm diameter using a chemical precipitation method. The resulting nanoparticles were characterized by X-ray diffraction analysis (XRD), Fourier-transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The optical properties were investigated by UV–vis and fluorescence techniques. The absorption spectra exhibit a sharp absorption edge at ～334 nm corresponding to band gap of ～3.7 eV. The fluorescence spectra displayed a near-band-edge ultraviolet excitonic emission at ～410 nm and a green emission peak at ～525 nm, due to a transition of a photo-generated electron from the conduction band to a deeply trapped hole. The photocatalytic activity of the prepared ZnO nanoparticles has been investigated for the degradation of ciprofloxacin drug under UV light irradiation in aqueous solutions of different pH values. The results showed that the photocatalytic degradation process is effective at pH 7 and 10, but it is rather slow at pH 4. Higher degradation efficiency (～50%) of the drug was observed at pH 10 after 60 min. Photodegradation of the drug follows a pseudo-first-order kinetics.     

Spectral absorption of tellurium in alkali borate glasses

The spectral absorption of tellurium-containing lithium, sodium and potassium borate glasses in the range of 300–700 nm was used to identify the states of tellurium formed in such glasses. Depending on the nature and concentration of the alkali oxide the glasses obtained were either colourless, rose which is attributed to the formation of the polytelluride ion or grey which is attributed to the formation of elemental tellurium particles. The tellurites and/or tellurates are expected to form in glasses of high content of either Na₂O or K₂O which were colourless. The sequence of formation of the different states of tellurium with increasing alkali content is in accordance with acidity-basicity concept.     

On the characteristics of the head-on collision between two ion thermal waves in isothermal pair-ion plasmas containing charged dust grains

The head-on collisions between two ion thermal solitary waves in isothermal pair-ion plasmas containing charged dust grains is investigated. Using the extended Poincaré-Lighthill-Kuo (PLK) method, the Korteweg-de Vries (KdV) equations and the analytical phase shifts after the head-on collision of two- solitary waves are derived. The results show that the number densities of positive and negative dust grains to the density of positive ion ratios and the negative-to-positive ion temperature ratio have strong effects on the phase shifts.