Extraction,identification and sorption studies of dyes from madder on wool

Since the last decade, the application of natural dyes on textile materials is gaining popularity all over the world, possibly because of increasing awareness of environment, ecology, and pollution control. In this research, extraction of dyes from madder at different conditions has been studied. The extracted dyes from madder were examined by TLC and HPLC. The adsorption properties of the dyes extracted from madder on natural polyamide fibers (wool) were also determined. The rate of dyeing at different temperatures, as well as the values of standard affinity, entropy, and enthalpy was calculated. The results indicated that increase of temperature leads to decrease the values of partition ratio and affinity. The adsorption isotherm was tested by fitting the adsorption data with Langmuir, Freundlich, BET, and Temkin isotherms. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

TCP-Aware Channel Allocation in CDMA Networks

This paper explores the use of rate adaptation in cellular networks to maximize throughput of long-lived TCP sessions. We focus on the problem of maximizing the throughput of TCP connections and propose a joint optimization of MAC and physical layer parameters with respect to TCP sending rate. In particular, we propose a simple TCP-aware channel scheduler that adapts the wireless channel rate to changes in the TCP sending rate and explore its performance for both single and multiple concurrent sessions. In the case of a single TCP session, we develop a fluid model of its steady-state behavior in such a system that adapts between two channel rates. Our results indicate that a two-rate scheme improves TCP throughput by 15% to 20% over a system that does not exploit rate adaptation and that little additional benefit accrues from the addition of a third channel rate. Finally, we extend the framework to scenarios where bandwidth is shared by multiple TCP sessions. We propose two channel allocation algorithms and explore their performance through simulation. Our results indicate that TCP throughput is relatively insensitive to either channel allocation algorithm and adaptive rate variation is the dominant factor in performance.     

Detection of flaws in a two-dimensional body through measurement of surface temperatures and use of conjugate gradient method

This paper aims to obtain parameters (i.e. location and dimensions) relevant to flaws in a two-dimensional body by measuring the temperature on its boundaries. In this endeavour, a steady-state heat conduction problem is formulated, and the geometry under study is subjected to a known heat load, resulting in a specific heat distribution in the body. By using a number of heat sensors, the temperature at selected points on the boundary of the body is obtained. Inverse heat conduction methods implement these temperature data, working toward estimating the flaw parameters. The objective function is optimized using conjugate gradients method, and in solving the direct problem, an FEM code is employed. To check the effectiveness of this method, sample cases with one or more circular, elliptical cavities or cracks in the body, and a case with unknown cavity shape is solved. Finally the ensuing results analyzed.     

Dynamic ageing and the mechanical response of Al–Mg–Si alloy through equal channel angular pressing

In this paper, dynamic ageing characteristics associated with the application of equal channel angular pressing (ECAP) to Al6061 alloy at elevated temperatures was investigated. Followed by ECAP, Vickers microhardness measurement on the cross-sectional planes and microstructural observations were undertaken using transmission electron microscopy. The combination of the ECAP process with dynamic ageing at both 100 °C and 150 °C resulted in a significant increase in hardness. The grain size was measured as ∼160 nm after four passes. A comparison with the published data on the same alloy processed by ECAP at room temperature and statically aged, suggests several advantages in incorporating dynamic ageing with ECAP. These advantages consist of the ability to attain better grain refinement, increased hardness and the potential for saving time and energy.     

Multi objective optimization of rotorcraft compact spinning system using fuzzy-genetic model

In this paper, the mechanical and physical properties of rotorcraft compact spinning yarns were evaluated. For this aim, the filament pre-tension, yarn count and type of sheath fibers were selected as the controllable factors, and the effect of them on the elongation and hairiness was investigated statistically and the obtained results indicated that controllable factors have significant effect on the measured properties. In the next step, the relation between factors and measured properties was modeled by fuzzy interface system and genetic algorithm was used to optimize the number of membership function and its kind. It was observed that the accuracy of obtained models for both elongation and hairiness is acceptable (correlation coefficient for both models was: 0.99). Finally, to find a set of controllable factors to produce a yarn with high elongation and low hairiness, multi objective optimization was applied by means of non-dominated sorting genetic algorithm and a set of trade off solutions obtained so that each solution can be accepted as a response.     

Enhanced-Oxidation and Highly Sensitive Detection of Tartrazine in Foodstuffs via New Platform Based on Poly(5-Sulfosalicylic Acid)/Cu(OH)<Subscript>2</Subscript> Nanoparticles

Poly(5-sulfosalicylic acid) (PSSA)/Cu(OH)₂ nanoparticle–graphite (Gr) nanocomposite-modified glassy carbon electrode (PSSA/Cu(OH)₂–Gr/GCE) was utilized for sensitive determination of tartrazine using squarewave voltammetry (SWV). The structure of the nanocomposite was investigated by transmission electron microscopy (TEM) and field emission scanning electron microscopy (FESEM(. PSSA/Cu(OH)₂–Gr/GCE exhibited an enhancement in anodic peak current, electron transfer kinetics, effective surface area, and reactive sites and indicated good electrocatalytic activity toward the oxidation of tartrazine. The as-proposed modified electrode achieved a satisfactory dynamic range between the anodic peak current and the concentration of tartrazine at two concentration ranges of 0.01–0.6 and 0.6–10 μmol/L, and the detection limit was obtained to be 8 nmol/L (S/N = 3). The resulting sensor was successfully used to determine tartrazine in real samples such as candy, softdrink, orange juice powder, banana-flavored jelly powder, and candy-coated chocolate.     

Absolute conductivity reconstruction in magnetic induction tomography using a nonlinear method

Magnetic induction tomography (MIT) attempts to image the electrical and magnetic characteristics of a target using impedance measurement data from pairs of excitation and detection coils. This inverse eddy current problem is nonlinear and also severely ill posed so regularization is required for a stable solution. A regularized Gauss-Newton algorithm has been implemented as a nonlinear, iterative inverse solver. In this algorithm, one needs to solve the forward problem and recalculate the Jacobian matrix for each iteration. The forward problem has been solved using an edge based finite element method for magnetic vector potential A and electrical scalar potential V, a so called A, A - V formulation. A theoretical study of the general inverse eddy current problem and a derivation, paying special attention to the boundary conditions, of an adjoint field formula for the Jacobian is given. This efficient formula calculates the change in measured induced voltage due to a small perturbation of the conductivity in a region. This has the advantage that it involves only the inner product of the electric fields when two different coils are excited, and these are convenient computationally. This paper also shows that the sensitivity maps change significantly when the conductivity distribution changes, demonstrating the necessity for a nonlinear reconstruction algorithm. The performance of the inverse solver has been examined and results presented from simulated data with added noise.     

Synthesis and characterization of polyrhodanine/nickel ferrite nanocomposite with an effective and broad spectrum antibacterial activity

Nickel ferrite nanoparticles were successfully synthesized via a co-precipitation approach, and then polyrhodanine/nickel ferrite nanocomposite (PRh/NiFe₂O₄) as an antimicrobial agent was fabricated by a chemical polymerization method. The synthesized NiFe₂O₄ nanoparticles and PRh/NiFe₂O₄ nanocomposite were chemically, magnetically and morphologically characterized using FTIR, FESEM, DLS, VSM and XRD techniques. The FESEM analysis showed that the NiFe₂O₄ nanoparticles had a polygon structure with an average diameter of 50 nm. According to disc diffusion as well as MIC and MBC tests, the PRh/NiFe₂O₄ nanocomposite had better antibacterial effects on killing Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli in comparison with the NiFe₂O₄ nanoparticles.     

Structural and optical study of Fe3+-doped Al2O3 nanocrystals prepared by new sol gel precursors

Pure and Fe-doped Al₂O₃ nanoparticles (NPs) were synthesized with different iron doping percentage of 1, 3, and 5 mol% employing sol gel technique with AlCl₃, FeCl₃ as well as ethylene glycol (EG) and Polyvinylpyrrolidone (PVP) stabilizers as precursors. The XRD results indicated that the hexagonal structure of Fe/Al₂O₃ nanocomposite with alpha phase was formed by the substitution of Fe³⁺ ions in the alumina network. The sizes of the NPs obtained for the pure samples and doped samples at percentage dopant of 5% were 35 and 28 nm, respectively. The results of FTIR optical analysis showed the vibrational bond at the wavelength of 448 cm⁻¹, indicating the Al-O band in the sample. The UV-DRS analysis showed that the energy band gap for the pure NPs was 4 eV, but with increase in iron dopant up to 5%, it decreased to 3.42 eV. In addition, the results of photoluminescence (PL) analysis demonstrated that with increase in doping percentage, the PL intensity diminished. VSM magnetic analysis showed that with increase in iron dopant, the ferromagnetic state emerged in the NPs at saturation magnetism of 0.136 emu/g. Finally, photocatalytic experimental results demonstrated that 5% Fe-doped Al₂O₃ NPs effectively degrade MB approximately 53%.     

Reaction Pathways of Nanocomposite Synthesized in-situ from Mechanical Activated Al–C–TiO<Subscript>2</Subscript> Powder Mixture

In-situ Al matrix composite was synthesized from Al–TiO₂–C powder mixtures using mechanical alloying and heat treatment, subsequently. The effect of ball milling on reaction processes of the resulting nanocomposite was investigated. The evaluation of powder mixture without mechanical activation showed that at 900°C aluminum reduced TiO₂, forming Al₃Ti and Al₂O₃. After 20 h mechanical activation of powder mixture, Al₃Ti and Al₂O₃ were fabricated. After that, by increasing milling time up to 30 h, no new phases formed. The DTA analysis of 30 h milled powder indicated two peaks after aluminum melting at 730 and 900°C. The XRD results confirmed that at 730°C, molten Al reacted with TiO₂ and C, forming Al₃Ti, Al₂O₃ and Al₄C₃. After that, at 900°C, Al₃Ti reacted with Al₄C₃, causing TiC formation. This results proposed that the TiC formation is associated by a series of reactions between intermediate products, Al₃Ti and Al₄C₃ and the resultant nanocomposite was successfully synthesized after 30 h milling and heated by DTA analysis up to 1200°C.