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The electrochemical technique was used to investigate the effect of surface corrugations on the rate of mass and heat transfer (by analogy) in a stirred tank reactor. Impeller rotational speed, impeller shape, corrugation peak to valley height, and corrugation orientation (horizontal or vertical) were among the variables investigated. Depending on the operating conditions, surface corrugation increased the volumetric mass transfer coefficient by a factor ranging from 1.16 to 3.7. Mass transfer data were correlated with dimensionless correlations of an average deviation of ±4.2 and ±5.49 for radial and axial flow turbines, respectively. The significance of the dimensionless equations in determining the rate of heat transfer from the corrugated wall to a cooling jacket was emphasized. [ABSTRACT FROM AUTHOR]

The rate of diffusion-controlled corrosion of an annulus under swirl flow was studied by measuring the limiting current of the cathodic reduction of potassium ferricyanide depolarizer in the presence and absence of polyox WSR-301 drag-reducing polymer. It was found that the rate of diffusion-controlled corrosion of the inner cylinder of the annulus increases with increasing swirl flow solution velocity and decreases with increasing the active height of the cylinder. The data in the absence of polymer (blank solution) under swirl flow were fitted by a dimensionless equation. The importance of this equation in predicting the rate of diffusion-controlled corrosion and the corrosion allowance during the design of the swirl flow equipment was highlighted. For a given set of conditions, the rate of accelerated swirl flow corrosion was much higher than that of axial flow. Drag reducing polymer was found to inhibit the rate of diffusion-controlled corrosion by a maximum of 23%, if other benefits of the polymer are considered such as the decrease in the shear stress and the associated decrease in the erosion-corrosion tendency besides the decrease in pressure drop and pumping power requirement it may be concluded that the use of drag-reducing polymers in industry is worthwhile. [ABSTRACT FROM AUTHOR]

In this study anodic oxidation of Cr2(SO4)3 was carried out in an air-sparged divided parallel plate cell. Variables studied were current density, Cr2(SO4)3 concentration, and superficial air velocity. The rate constant of Cr2(SO4)3 oxidation was found to increase with increasing current density and Cr2(SO4)3 concentration. The effect of air sparging was found to depend on Cr2(SO4)3 concentrations, at high Cr2(SO4)3 concentration (> 0.1 M) air sparging does not affect the rate constant of the reaction denoting that the reaction is charge transfer controlled. As Cr2(SO4)3 concentration decreases below 0.1 M the reaction becomes under mixed diffusion and chemical control and the rate constant increases with increasing air superficial velocity, the lower Cr2(SO4)3 concentration the higher the contribution of diffusion to the reaction rate. The current efficiency of the process ranged from 20 to 85% depending on current density and Cr2(SO4)3 concentration. Electrical energy consumption which ranged from 1.8 to 14.4 kW h/kg of Cr6+ was found to increase with increasing current density and decreases with increasing Cr2(SO4)3 concentration. Air sparging was found to decrease electrical energy consumption in the case of dilute solutions << 0.1 M Cr2(SO4)3. [ABSTRACT FROM AUTHOR]

Rates of mass and heat transfer (by analogy) at the surface of a helical coil imbedded in a fixed bed of inert cylindrical packing were measured under upward two-phase (gas-liquid) flow by the electrochemical technique. The effects of geometrical and hydrodynamic parameters were considered. The performance of cylindrical packing was compared with that of Raschig rings and spheres. The analogy between heat and mass transfer was discussed and the importance of the present study for the design and operation of heterogeneous reactors that need rapid cooling in case of highly exothermic reactions was highlighted. [ABSTRACT FROM AUTHOR]

A conjugated semiconductor thin film of 1-((3-(3-(3,5-diphenyl-4,5-dihydro-1H-pyrazol-1-yl)-5-methyl-1H-1,2,4-triazol-1-yl)-1-phenyl-1H-pyrazol-4-yl)methyl)-4-phenyl-1H-1,2,3-triazole [4ph-TAzole]TF was synthesized. The fabricated [4ph-TAzole]TF thin film with a thickness of 150 ± 3 nm is manufactured by physical vapor deposition technique (PVD) at a low deposition rate with basic pressure of the chamber was 5 × 10−5 mbar. Using DFT-TDDFT simulation, the structure measurements the energy gap, and optical properties were determined. The obtained DFT-TDDFT data provide good proof for the electronic transition in zero-dimensional [4ph-TAzole]TF as a single crystal molecule. This study provides valuable information on the nature and sources of defect formation and electronic transition in conductor organic derivate of triazole which opens the way for the application as an optoelectronic device. [ABSTRACT FROM AUTHOR]

A semiconductor copolymer, HCl doped poly (para-nitro aniline-co-para-toluidine) [DPPNPT] was prepared by oxidative polymerization route in an acidic medium. The structural properties of the copolymer were characterized by several techniques. Physical vapor deposition technique was used for fabrication of the copolymer thin film [DPPNPT]TF of 100 nm thickness. Material studio 7.0 was calculated with the density functional theory (DFT), geometrical trials including the highest molecular orbits (HOMOs), the lowest unoccupied molecular orbitals (LIMOs), and the other active parameters were obtained. The optical parameters have demonstrated that the thin film has a high absorption range of 2 to 6 eV. Dosimetric properties are considered as another utilization of DPPNPT thin film. Thermoluminescence (TL) properties such as glow curves, different gamma doses response, and dose fading nature were tested. Thermoluminescence examinations of DPPNPT gamma-irradiated showed a single strong TL glow peak located at 350°C. Three unresoluted glow peaks of the [DPPNPT]TF films after gamma irradiation have been obtained. A linear correlation was obtained in the response curve start with 0.01Gy and extended to 2Gy. The total integral value of the TL signal showed a fixation through one month of storage of the DPPNPT compound. TL kinetics in deep traps were used to calculate resolute peaks activation energies. Based on obtained results the [DPPNPT]TF films are a good candidate for detection and monitoring personal gamma-ray doses. [ABSTRACT FROM AUTHOR]

To contribute to quantifying the process of electropolishing, the rates of electropolishing of a horizontal cylinder with active ends were studied under natural convection by measuring the limiting current of the anodic dissolution of copper cylinders in H3PO4. Cylinder diameters and H3PO4 concentrations were changed to provide a wide range of Sc⋅Gr (Schmidt and Grashof numbers). The data for a horizontal cylinder with active ends for the conditions 8.3 × 10 4 < Sc < 3.6 × 10 5 , 6.5 × 108 < Sc⋅Gr > 1.6 × 10 11 were correlated by the equation S h = 0.049 (S c. G r) 0.3 . For hollow horizontal cylinders (pipes) the outer surface data fit the equation S h = 0.8 (S c. G r) 0.28 . Comparison of the equations obtained for a horizontal cylinder with the equations obtained by previous studies on vertical cylinders with active ends revealed that the orientation of the workpiece plays an important role in determining the rate of electropolishing. [ABSTRACT FROM AUTHOR]

Effect of upward two-phase gas-liquid flow on the rate of liquid-solid mass transfer in a bubble column equipped with a horizontal tube bundle was studied by measuring the rate of the diffusion-controlled dissolution of copper in an acidified K2Cr2O solution. Variables studied included gas (nitrogen) flow rate, liquid flow rate, and the number of tube arrays. Data were successfully correlated by a dimensionless equation. The presence of surfactants reduced the rate of mass transfer by 3–17% depending on flow rates. The importance of the tube array as a built-in heat exchanger and a catalyst support was highlighted. [ABSTRACT FROM AUTHOR]

Rates of mass transfer in a spiral coil were measured by a technique involving the diffusion-controlled dissolution of copper in acidified dichromate. The variables studied were solution velocity, spiral tube pitch, and physical properties of the solution. The data were correlated by the equation S h = 0.189 S c 0.33 D e 0.55 P d 0.29 For a given set of conditions, the mass transfer coefficient predicted from the above equation was found to be much higher than that of the straight tube. Comparison of the ratio between the mass transfer coefficient and pressure drop for spiral tubes and straight tubes has revealed that k Δ p for spiral tubes is much higher than that of a straight tube under the present range of conditions. The possibility of using the above equation in predicting the rate of diffusion-controlled corrosion and the corrosion allowance needed to design a spiral tube heat exchanger was noted. Other possible applications in heterogeneous reactor design and membrane processes are reported. [ABSTRACT FROM AUTHOR]

The influence of a helical coil turbulence promoter on liquid-solid mass transfer rates in a stirred tank was investigated using a technique that involved measuring the rate of diffusion-controlled copper dissolution in acidified dichromate. The study examined the effects of helical coil tube diameter (d), helical coil pitch (p), impeller rotation speed, impeller geometry (axial and radial), the presence of baffles, and solution physical properties. The presence of the helical coil near the reactor wall significantly enhanced mass transfer rates, with a factor ranging from 1.01 to 2.48. This improvement was accompanied by a corresponding increase in the volumetric mass transfer coefficient (kA), ranging from 2.68 to 4.55, depending on operating conditions. Further analysis revealed that the average mass transfer coefficient increased with decreasing coil tube diameter, while coil pitch had a minimal impact. Additionally, radial flow turbines demonstrated superior mass transfer performance compared to axial flow turbines. The presence of baffles also promoted higher mass transfer rates compared to unbaffled reactors. The experimental data were successfully correlated using dimensionless correlations, emphasizing the significance of these correlations in scaleup and design optimization of catalytic stirred tank reactors with efficient cooling systems. [ABSTRACT FROM AUTHOR]

This paper presents a new approach for Loss of Excitation (LOE) faults detection in hydro-generators using adaptive neuro fuzzy inference system. The proposed scheme was trained by data from simulation of a 345 kV system under various faults conditions and tested for different loading conditions. Details of the design process and the results of performance using the proposed technique are discussed in the paper. Three techniques are used in this article based on the type of inputs to the proposed ANFIS unit, the generator terminal impedance measurements (RandX), the generator RMS Line to Line voltage and Phase current (VtrmsandIa) and the positive sequence components of the generator voltage magnitude, phase current magnitude, and angle (│V+ve│, │I+ve│, and ∟I+ve). The obtained results from these schemes are compared with each other and are compared with other techniques. The results show that the proposed technique is effective in detecting the LOE faults and the obtained results are very encouraging. [ABSTRACT FROM PUBLISHER]

Removal of CN−from liquid solutions was studied experimentally by an anodic oxidation technique under various operating conditions. A new cell configuration was used, the cell consists of four vertical graphite rod anodes distributed at 90° on the circular circumference at a distance of 3 cm from the wall and surrounded by two cylindrical stainless steel screen cathodes from the inner and the outer side. Parameters investigated are the initial concentration of cyanide ions, applied current density, initial pH of the electrolyte, and electrolyte conductivity. All parameters were investigated at an operating time of 3 h. The % removal increased upon increasing the applied current density, increasing the electrolyte conductivity, and decreasing the initial concentration of CN−. Increasing initial pH from 4 to 8 increased the % removal by a factor ranging from 55 to 73%, further increase of pH up to 12 slightly increased the % removal (3–8%). Application of the present electrochemical reactor in treating cyanide containing effluents from different industries was highlighted. [ABSTRACT FROM AUTHOR]

Two groups of 4-(4'-substituted phenylazo)-2-phenyl-4''-alkoxy benzoates were prepared and their mesophase formation and stability investigated. Each group (Ina-e and IIna-e) constituted five homologous series differing in their terminal substituent, CH3O, CH3, H, Cl or NO2. Within each series the number of carbons in the terminal alkoxy chain was 8, 10, 12, 14 or 16. The two main groups of compounds (I and II) differed in the polarity of the lateral substitutent attached to the central benzene ring. Group I had a chlorine atom adjacent to the ester group, replaced in Group II by the weakly electron-donating methyl group. Binary phase diagrams were constructed in which the two components were terminally-substituted analogues from within each group. The study was designed to investigate the effect of a lateral chloro or methyl group on the mesomorphic properties of the resulting derivatives, in pure or mixed states. The mesophase behaviour of the compounds themselves and their binary mixtures was investigated by differential scanning calorimetry and polarised light microscopy. The nematic phase was exhibited in most of the compounds, including their binary mixtures. [ABSTRACT FROM AUTHOR]

This work is a part of long program for producing natural polymers which is used for application in different purposes in agriculture fields. A part of this program was the preparation of various compositions of Gum Arabic (GA) and Poly vinyl alcohol (PVA) with studying its physical and chemical characters. Whereas, the present work was concerning with the evaluation of released amount of selected micronutrients from the same complex under laboratory and field conditions. In the laboratory, the prepared complex containing copper (Cu) or manganese (Mn) separately, were tested at different pH values for releasing at intervals. The obtained results showed the possibility of using the Mn+2 complex at 3000 mg kg-1. Moreover, the obtained results showed that the maximum released amount was obtained at pH 7.0. A field experiment was planed according to the resulted data obtained in laboratory. Samples were taken for elemental analysis either from soil or plants during all growth stages likeas vegetative, flowering, bear pods, full pods and harvesting. This analysis involved some selected macro- and micro nutrients such as N, P, K, Fe and Mn either in soil or plants (straw and seed). These results proved that efficiency of Mn-complex can release 1.0 and 34.0% to soil, and plants from used complex, respectively. Some increase in most of other elements compared with untreated plants was also obtained. The presence of the absorbed Mn+2 from this complex activate the growth of plants and consequently increased the yield of seed than untreated samples. There is a linear relationship between the amount of absorbed Mn+2 and the growth stages of the plants. This linear relationship has significant correlation coefficient (R2 = 0.5) of Mn+2 uptake by straw or seed plants after end of stages. [ABSTRACT FROM AUTHOR]

This article aims to present a new approach based on C 1 -cubic splines introduced by Sallam and Naim Anwar [Sallam, S. and Naim Anwar, M. (2000). Stabilized cubic C 1 -spline collocation method for solving first-order ordinary initial value problems, Int. J. Comput. Math. , 74 , 87-96.], which is A-stable, for the time integration of parabolic equations (diffusion or heat equation). The introduced method is an example of the so-called method of lines (the solution is thought to consist of space discretization and time integration), which is an extension of the 1/3-Simpson's finite-difference scheme. Our main objective is to prove the unconditional stability of the proposed method as well as to show that the method is convergent and is of order O ( h 2 ) + O ( k 4 ) i.e. it is a fourth-order in time and second-order in space. Computational results also show that the method is relevant for long time interval problems. [ABSTRACT FROM AUTHOR]

Tests a structural model involving training and work environment variables for workers with disabilities in the United Arab Emirates and Jordan. Factors positively influencing the disabled workers' view on work; Impact of factor representing trainers on the view on the work environment.

The study aims to explore attitudes of the United Arab Emirates University students towards the handicapped. A sample of 313 students, conventionally drawn, took the College Students' Attitude Scale towards the Handicapped. Statistical analysis revealed significant differences in favour of females vs males, single vs married, residents vs non‐residents, families with handicapped children, previous contact with handicapped and urban vs rural groups. Several recommendations are suggested at the end of the study. [ABSTRACT FROM PUBLISHER]

This study examines liquid-solid mass and heat transfer rates in serpentine tube heat exchangers/reactors under turbulent flow using the copper dissolution technique. Key factors include solution flow rate, properties, tube diameter, U-bend curvature, and drag-reducing polymers. An empirical correlation predicts mass transfer coefficients, which are 4.12–5.36 times higher than straight tubes. Serpentine tubes show potential for economically viable diffusion-controlled reactions. Drag-reducing polymer (Polyox WSR-301) reduces corrosion rates by up to 23.3%. The study highlights serpentine tubes’ applicability in catalytic continuous reactors and membrane processes, emphasizing their significance in heat exchanger design and corrosion allowance prediction. [ABSTRACT FROM AUTHOR]