Band 234, Heft 1

The present paper deals with the minima of conductivity in aqueous solutions, which occur due to the hydrolysis reaction with added bases. The minima show lower conductivities than the intrinsic conductivity of pure water. The minimum is a function of the molar conductivity of the added ions. There exists a limiting condition of <75.825 ⋅ 10 −4 S ⋅ m 2 ⋅ mol −1 for the occurrence of a minimum in the real (positive) concentration area. Values higher than 75.825 ⋅ 10 −4 S ⋅ m 2 ⋅ mol −1 lead to minimas in the virtual (negative) concentration area. Connecting all the minima, a curve with a maximum is observed. This point is given by 75.825 ⋅ 10 −4 S ⋅ m 2 ⋅ mol −1 and the intrinsic conductivity of pure water. The effect is independent of whether the added substances come from a strong or weak base. So far, the phenomenon should not influence measurements of conductivity under usual circumstances, but might be more of academic interest. Interestingly, we found that the effect for Rubidium and Cesium ions is different compared to other alkali metal ions. No minimum conductivity is predicted for these ions.

Here in this study timing saving, easy and cost effective methods has been applied for fabricating the dielectric energy storage materials. Ceramic nanoparticles (FLZC’s) have been successfully synthesized by Sol-Gel method and its nanocomposites with non-conducting polymers (PVP, PVA, PEG, PEO) and multiwalled carbon nanotubes (MWCNT’s) by one-pot blending technique. Energy dispersive x-ray diffraction (EDX), x-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transforms infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA/DTA), AC impedance analyzer and dielectric properties were determined for all the samples. Dielectric properties showed good agreement with that of energy storage substances for electronic device fabrication. High dielectric constant was achieved when 0.5 wt% MWCNT’s was added to FLZC’s/MWCNT’s/Polymer nanocomposites. The stability and performance of the nanocomposites were dependent on the type of polymer used. These preparation materials can be employed in functional materials, such as high charge-storage capacitors, electrostriction for artificial muscles and smart skins etc.

In the present study, we have synthesized conducting polymer nanocomposites consist of silver nanoparticles (AgNPs), graphene, and polyvinyl acetate (PVAc) emulsion. The synthesized nanocomposite was characterized by UV/Vis, FT-IR, XRD, TGA, and SEM techniques. SEM images showed that AgNPs and graphene sheets are well dispersed in the PVAc matrix. The electrical conductivities of the nanocomposites were examined using the impedance analyzer instrument. It was ascertained that polymer composite containing silver nanoparticles and graphene exhibit higher conductivities. The PVAc-AgNPs/Graphene nanocomposite was also used as potential conducting materials for humidity measurement.

In the current effort, the Co–Ni–Cr Nanocomposites were synthesized by chemical method and characterized by means of scanning electron micrographs (SEM), X-ray diffraction (XRD), Fourier trans from infra-red (FTIR), and vibration sample magnetization (VSM). In the final step, these nanoparticles were used to study the nitrate removal efficiency from aqueous solution. The effect of important factor including pH, concentration of Nitrate (NO 3 − ) ion, contact time and nanoparticle dose were studied in order to find the optimum adsorption conditions. A maximum of removal of the nitrate was observed at pH 4, initial concentration of 40 mg L −1 , amount of nanoparticle of 0.06 g L −1 and contact time 60 min. The adsorption isotherm values were obtained and analyzed using the Langmuir, Frenudlich, Temkin and Dubinin–Radushkevich equations, the Temkin isotherm being the one that showed the best correlation coefficient (R 2 = 0.999). In addition to, the adsorption kinetics studied by the pseudo-first-order, pseudo-second-order, Elovich model, Ritchie and intraparticle diffusion models. The experimental data fitted to pseudo-second-order (R 2 = 0.999).

The new compound 4-(2-(1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)hydrazono)-3-methyl-5-oxo-4,5-dihydro-1H-pyrazole-1-carbothioamide (PY) was synthesized. Its anti-corrosion properties for C-steel in acid solution (1.0 M HCl) were evaluated utilize electrochemical tools. The synthesized compound was described using FT-IR and 1 H-NMR analyses. The purity of PY was affirmed by thin-layer chromatography (TLC). The outcome data proved that PY possess adequate anti-corrosion features for C-steel in corrosive solution. The polarization parameters mentioned that the PY is a mixed inhibitor. Inhibition performance obtained by polarization measurements (i.e. 91.5%) are consistent with the one obtained by EIS (i.e. 88.6%). Quantum chemical parameters for PY were studied to supply assist knowledge into the anti-corrosion properties of the new compound.

An in-situ electrochemical polarization study was used to investigate the erosion-corrosion (E-C) behavior of C-steel in Egyptian crude oil-water mixture (ECWM) under mimetic different conditions. The anodic polarization responses for C-steel in ECWM are recognized active-passive region. Flow rate, sand particles and temperature increased the E-C rate. Disintegration rate to erosion rate proportion (E/C) was calculated and talked about.

The Fourier transform infrared and Raman spectra of two adamantane-containing triazole thiones, namely 3-(adamantan-1-yl)-1-[(4-benzylpiperazin-1-yl)methyl]-4-phenyl-1 H -1,2,4-triazole-5(4 H )-thione and 3-(adamantan-1-yl)-4-phenyl-1-[(4-phenylpiperazin-1-yl)methyl]-1 H -1,2,4-triazole-5(4 H )-thione, were examined in the ranges of 3200–650 cm −1 and 3200–150 cm −1 , respectively. The density functional theory calculations were performed for the geometric structures and vibrational spectra for the title molecules. The accurate equilibrium geometry structures of the molecules were determined on the basis of full geometry optimization at the B3LYP/cc-pVDZ level of the theory. The IR and Raman vibrational spectra were calculated and compared with the experimental ones. The experimental vibrational FT-IR and Raman spectra were interpreted. Based on the structure of the molecules the biological activity indices were predicted. It is established that compounds under consideration are very likely to exhibit the analgesic activities. The UV/Vis spectra of solution of the compounds in ethanol were measured in the range of 450–200 nm. The UV/Vis spectra simulations at the Time-Dependent DFT and Multi-Reference Perturbation Theory levels of theory demonstrate unsuitability of the TDDFT for description of the experimental spectra of the title molecules. It is highly probable that this is a consequence of the intramolecular charge transfer. In contrast, the MRPT results are in a good agreement with the experimental spectra.

The wet granular material creates networks in which interstitial liquid provides capillary bridges needed to hold grains together. There is an optimal fraction of the interstitial liquid in which the bridges are formed and the friction coefficient is minimal. We found that the size of the grains affects the friction of wet granular media. Our observations demonstrates that the optimum volume fraction, in which the friction coefficient is minimized, increases with grain size, but for sand immersed in water, this minimum friction coefficient itself increases with size and for glass beads immersed in silicone oil it decreases, indicating that the shape of the grains also has an effect on this friction. It is also shown that there is a crossover point for grain size at which the network effect created by capillary bridges is dominated by wet granular media. This crossover point is found.

The present study is focused on the thermal decomposition of Levofloxacin in the absence and presence of different excipients (sodium starch glycolate, magnesium stearate, microcrystalline cellulose and lactose using Thermogravimetry (TG). Fourier Transform Infra Red Spectroscopy (FTIR) and Differential Scanning Calorimetry (DSC) were used to study the possible drug – excipient interaction. It has been shown that the interaction of the first three excipients (sodium starch glycolate, magnesium stearate, and microcrystalline cellulose) with Levofloxacin is physical in nature. Lactose was shown to decrease the degradation temperature to a maximum extent. This indicates a strong chemical interaction between the drug and lactose. The activation energies in the former case were found almost similar but deviated considerably in the latter case.

In view of promising efficiency of advanced oxidation process, ZnO/UV/H 2 O 2 based advanced oxidation process (AOP) was employed for the degradation of Disperse Red-60 (DR-60) in aqueous medium. The process variables such as concentration of catalysts, reaction time, pH, dye initial concentration and H 2 O 2 dose were evaluated for maximum degradation of dye. The maximum degradation of 97% was achieved at optimum conditions of H 2 O 2 (0.9 mL/L), ZnO (0.6 g/L) at pH 9.0 in 60 min irradiation time. The analysis of treated dye solution revealed the complete degradation under the effect of ZnO/UV/H 2 O 2 treatment. The water quality parameters were also studied of treated and un-treated dye solution and up to 79% COD and 60% BOD reductions were achieved when dye was treated with at optimum conditions. The dissolved oxygen increased up to 85.6% after UV/H 2 O 2 /ZnO treatment. The toxicity was also monitored using hemolytic and Ames tests and results revealed that toxicity (cytotoxicity and mutagenicity) was also reduced significantly. In view of promising efficiency of UV/H 2 O 2 /ZnO system, it could possibly be used for the treatment of wastewater containing toxic dyes.

3-(3,4-dimethoxyphenyl)-1-(2,5-dimethylfuran-3-yl)prop-2-en-1-one (DDFP), is prepared by the equimolar ratio of 1-(2,5-dimethylfuran)ethan-1-one and 3,4, dimethoxy benzaldehyde under ultrasonic irradiation. Structure of DDFP was established by the FT-IR, 1 H and 13 C-NMR spectroscopic methods and elemental analysis. The nonlinear optical properties of this dye using the z-scan technique with a cw argon ion laser at 514.5 nm are studied. Both the closed and open aperture z-scan data is used to estimate the nonlinear refractive index n 2 and the nonlinear absorption coefficient β respectively. The measurements are carried out at five concentrations as well as at five laser powers. The values obtained are relatively very high and vary linearly with concentration. The studies on optical limiting behavior of this dye are also reported here.

The YMnO 3 , NiO, and NiO/YMnO 3 nanocomposites are successfully prepared by a polyacrylamide gel method and a simple two phase recombination route. The phase structure, surface morphology, optical, magnetic and electrochemical properties and photocatalytic activity of as-prepared samples were measured by X-ray diffraction (XRD), Scanning electron microscope (SEM), UV-visible spectrophotometer, superconducting quantum interference device (SQUID), electrochemical workstation and 721 spectrophotometer. Phase structure analysis indicate that the YMnO 3 , NiO, and NiO/YMnO 3 nanocomposites has good crystallization and no other impurities. The NiO supported YMnO 3 composites improved the surface morphology, optical, magnetic and electrochemical properties and photocatalytic activity of YMnO 3 nanoparticles significantly. Photocatalytic experiment analysis indicate that the NiO supported YMnO 3 composites exhibits highest photocatalytic activity for degradation of the methyl red dye with dye concentration of 25 mg/L. The excellent photocatalytic activity for the NiO supported YMnO 3 composites can be ascribed to the fast interfacial charge transfer, high effective charge separation and the ⋅ OH radicals.