Metachromic interactions between azo and triphenylmethane dyes in aqueous solution. II. The effect of organic solvents on the interaction

The interaction between dilute aqueous solutions of the disazo dye Brilliant Orange and the triphenylmethane dye Crystal Violet results in a decrease in the absorption of Crystal Violet in the region 550–600 nm and the appearance of a new absorption at 494 nm. The decrease in absorbance at 590 nm is characteristic of the metachromic interactions of Crystal Violet with a wide variety of polyanion substrates while the increase at 494 nm is due to the conversion of Brilliant Orange from its azo to its hydrazone tautomer. The relative effects of a variety of organic solvents in reversing the interaction has been investigated.     

Photon conductivity of metallurgical slags of the three component system CaO-SiO2-Al2O3

The measuring method proposed by Keene and Quinn has been further developed to investigate 3-component slags of the system CaO-SiO₂-Al₂O₃ at temperatures of 800–1600°C in the wavelength range of 550 to 850 nm. The results are presented with the aid of the complex refraction index, which embodies all information on the optical properties of the slags investigated, including photon conductivity and thermal emissivity. Comparison of the photon conductivities determined shows good agreement with the corresponding values of various types of glass cited in literature. The discontinuous pattern of the phonon conductivity curve in the melting range of 40% CaO-40% SiO₂-20% Al₂O₃ slag, as already found by Gammal and Li, is also evident from the data of the present investigation.     

Praxisorientierte Raffination von Stahlschmelzen mit Seltenerdmetallen

Simulation eines pfannenmetallurgischen Stahlraffinationsverfahrens unter Verwendung von Cer-Mischmetall, einer Raffinationsschlacke und Argonspülung zur Reinheitsgradverbesserung. Darstellung typischer nichtmetallischer Einschlüsse. Aufzeigen der erzielten Zähigkeitsverbesserungen und der Verringerung der Zähigkeitsanisotropie.     

Photocatalytic oxidation of ciprofloxacin under simulated sunlight

Ciprofloxacin (CIP) is a famous synthetic chemotherapeutic antibiotic. It is widely found either in water or wastewater. In this study ciprofloxacin was photocatalytically degraded using commercial anatase titanium dioxide (TiO(2)) under simulated sunlight. The rate of reaction was found to be affected by pH, TiO(2) concentration and antibiotic concentration. The best reaction rate was obtained in natural ciprofloxacin pH (5.8) and 1000 mg/L TiO(2). More titania concentration was found to reduce the reaction rate because of the limitation in light transmittance. From kinetic studies, the reaction was proved to proceed through adsorption step then photooxidation and obeys pseudo-first order kinetics.     

Copper cation removal in an electrokinetic cell containing zeolite

Zeolites are used in environmental remediation of soil or water to immobilize or remove toxic materials by cation exchange. An experiment was conducted to test the use a low electric field to direct the toxic cations towards the zeolite. An electrokinetic cell was constructed using carbon electrodes. Synthetic Linde Type A (LTA) zeolite was placed in the cell. Copper(II) chloride dissolved in water was used as a contaminant. The Cu(2+) concentration was measured for ten hours with and without an applied electric field. The removal of the Cu(2+) ions was accelerated by the applied field in the first two hours. For longer time, the electric field did not improve the removal rate of the Cu(2+) ions. The presence of zeolite and applied electric field complicates the chemistry near the cathode and causes precipitation of Cu(2+) ions as copper oxide on the surface of the zeolite. With increased electric field the zeolite farther away from the cathode had little cation exchange due to the higher drift velocity of the Cu(2+) ions. The results also show that, in the LTA Zeolite A pellets, the cation exchange of Cu is limited to a shell of several tens of micrometers.     

Nutritional and physicochemical evaluations of tahina (sesame butter) prepared from heat‐treated sesame seeds

Dehulled sesame seeds were roasted using different heat treatments. The effects of roasting treatments on the nutritive value, physicochemical properties and sensory properties of produced tahina were studied. Resultant tahina contained 586–594 g kg⁻¹ crude oil, 219–226 g kg⁻¹ crude protein and <30 g kg⁻¹ crude fibre and ash. Crude protein, crude fibre, ash and N‐free extract in tahina samples were not affected by roasting treatments. However, crude oil was decreased by steam roasting and hot plate roasting. Hot plate roasting was more effective in reducing raffinose content than other roasting treatments, whereas vacuum roasting was less effective in reducing raffinose content than other roasting treatments. Tahinas were good sources of essential amino acids, especially sulphur‐containing amino acids, aromatic amino acids and tryptophan. Hot air roasted tahina followed by vacuum roasted tahina had higher total essential amino acid contents than steam roasted and hot plate roasted tahinas. Lysine was the first limiting amino acid in tahinas. Tahinas had a relatively high in vitro protein digestibility (over 83%). Tahina is a good source of niacin. Hot air roasted tahina had the highest content of B group vitamins compared with other tahina samples. Resultant tahinas had relatively high amounts of Na, Mg, K, Cu, Zn and Fe and a low amount of Ca. Roasting treatments did not affect the mineral contents. All roasted samples had a typical protein spectrum with a maximum absorption at 280 nm and minimum at 260 nm. However, the spectrum of hot air roasted tahina proteins was sharper than the spectra of other tahina proteins. Size exclusion HPLC fractionated tahina proteins into two fractions for hot roasted and vacuum roasted tahinas and three fractions for steam roasted and hot plate roasted tahinas. The gel filtration pattern of tahina proteins contained four peaks with identical elution volumes but different proportions. Hot air roasted and vacuum roasted tahinas had higher panel scores than steam roasted and hot plate roasted tahinas for all tested sensory properties. © 2000 Society of Chemical Industry     

Estimation of solar radiation components incident on Helwan site using neural networks

Field testing carried out for solar energy applications is costly, time consuming and depends heavily on prevailing weather conditions. Adequate security and weather protection must be provided at the test site. Measurements may also suffer from delays that can be caused by system failures and bad weather. To overcome these problems the need for accurate model becomes evermore important. To achieve such prediction task, an artificial neural network, ANN, model is regarded as a cost-effective technique superior to traditional statistical methods. In this paper, Levenberg optimization function is adopted to predict insolation data in different spectral bands for Helwan (Egypt) monitoring station. The predicted values were then compared with the actual values and presented in terms of usual statistics. The results hint that, the ANN model predicted infrared, ultraviolet, and global insolation with a good accuracy of approximately 95%, 93% and 96%, respectively. In addition, ANN model was tested to predict the same components for Aswan over an 11 month period. The predicted values of the ANN model compared to the actual values for Aswan produced an accuracy of 95%, 91% and 92%, respectively. Data for Aswan were not included as a part of ANN training set. Hence, these results demonstrate the generalization capability of this approach over unseen data and its ability to produce accurate estimates.     

Rigorous Full-Wave Analysis of Rectangular Microstrip Patch Antenna on Suspended and Composite Substrates

In this paper, Galerkin’s method in the Fourier transform domain is applied to the determination of the resonant frequencies and half-power bandwidth of rectangular microstrip patch on composite and suspended substrates. Using Galerkin’s method in solving the integral equation numerically, the complex resonant frequency of the microstrip antenna on suspended and composite substrates is studied with sinusoidal functions as basis functions, which show fast numerical convergence. The validity of the solution is tested by comparison of the computed results with experimental data. Finally, numerical results for the effects of suspended and composite substrates on the resonant frequency and half-power bandwidth are also presented.     

An adjusted K‐medoids clustering algorithm for effective stability in vehicular ad hoc networks

Recently, the routing problem in vehicular ad hoc networks is one of the most vital research. Despite the variety of the proposed approaches and the development of communications technologies, the routing problem in VANET suffers from the high speed of vehicles and the repetitive failures in communications. In this paper, we adjusted the well‐known K‐medoids clustering algorithm to improve the network stability and to increase the lifetime of all established links. First, the number of clusters and the initial cluster heads will not be selected randomly as usual, but based on mathematical formula considering the environment size and the available transmission ranges. Then the assignment of nodes to clusters in both k‐medoids phases will be carried out according to several metrics including direction, relative speed, and proximity. To the best of our knowledge, our proposed model is the first that introduces the new metric named “node disconnection frequency.” This metric prevents nodes with volatile and suspicious behavior to be elected as a new CH. This screening ensures that the new CH retains its property as long as possible and thus increases the network stability. Empirical results confirm that in addition to the convergence speed that characterizes our adjusted K‐medoids clustering algorithm (AKCA), the proposed model achieves more stability and robustness when compared with most recent approaches designed for the same objective.