A Study on the Impact of the Adhesion of Penicillium expansum on the Physicochemical Surface Properties of Cedar Wood

The sessile drop technique was used to investigate the evolution of the physicochemical properties of cedar wood as a function of contact time with the Penicillium expansum spores. The most important finding showed that the impact of different contact periods (2, 4, 6, 8, 10, and 24 hr) on the wood surface were very indicative. In fact, after 2 hr of contact, the results have shown a significant impact of the bioadhesion of spores to the substrate on both the hydrophobic character (θ_W = 108.5°; ΔGiwi = ?28.25 mJ/m²), the electron donor (γ^? = 13.63 mJ/m²), and the electron acceptor (γ⁺ = 4.35 mJ/m²) parameters that were significantly reduced compared to the initial wood (θ_W = 118.5°; ΔGiwi = ?6.29 mJ/m²; γ^? = 32.1 mJ/m²; and γ⁺ = 9.1 mJ/m²). In addition, this decrease of parameters continued over time to stabilize after 10 hr of contact. Indeed, after 24 hr, the acid/base properties were almost zero and the contact angle with water decreased to 30°. Moreover, it was found that the coefficient of correlation (r²) was strong between the contact angle with water, the surface energy, and the electron acceptor character with the contact time parameter with values (r² = 0.65), (r² = 0.79), and (r² = 0.68), respectively.     

Polyolefin elastomer grafted unsaturated hindered phenol esters: synthesis and antioxidant behavior

Monomeric antioxidants are synthesized from esterification of 3,5-di-tert-butyl-4-hydroxybenzoic acid and 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid with unsaturated fatty alcohols. The antioxidant activity is evaluated both in blending and radical grafting processes. The effect of chain length and phenolic group is investigated on efficiency of antioxidants. It is demonstrated that the esters of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid exhibit significantly longer induction time. The results of radical grafting reaction shows synthesized antioxidants can be successfully grafted onto polymer chains and the phenolic moiety is functional after extraction process, while pure and commercially stabilized samples are degraded instantaneously. Also, different initiator systems are utilized to enhance the extent of grafting. Among MEK, DCP, and DHBP peroxides, DHBP can be more effective in increasing the antioxidant grafted onto polymer. In addition, possibility of rising in graft content is investigated in presence of redox initiator. Using this approach, polymer-bound antioxidant with prolonged thermal stability can be achieved.     

Computational analysis of a three-dimensional high-velocity oxygen fuel (HVOF) thermal spray torch

An analysis of a high-velocity oxygen fuel thermal spray torch is presented using computational fluid dynamics (CFD). Three-dimensional CFD results are presented for a curved aircap used for coating interior surfaces such as engine cylinder bores. The device analyzed is similar to the Metco diamond jet rotating wire torch, but wire feed is not simulated. The feed gases are injected through an axisymmetric nozzle into the curved aircap. Argon is injected through the center of the nozzle. Premixed propylene and oxygen are introduced from an annulus in the nozzle, while cooling air is injected between the nozzle and the interior wall of the aircap. The combustion process is modeled assuming instantaneous chemistry. A standard, two-equation, k-ε turbulence model is employed for the turbulent flow field. An implicit, iterative, finite volume numerical technique is used to solve the coupled conservation of mass, momentum, and energy equations for the gas in a sequential manner. Computed flow fields inside and outside the aircap are presented and discussed.     

Neodymium(III)-PVC membrane sensor based on a new four dentate ionophore

A new selective Nd(III) sensor has been made by using N,N′-bis(quinoline-2-carboxamido)-4,5-dimethylbenzene (H₂L₄) as a suitable ionophore. The sensor exhibits Nernstian response to Nd(III) ions in the concentration range of 5.0 × 10^− 6 to 1.0 × 10^− 2 M. It displays a Nernstian slope of 19.5 ± 0.4 mV/decade in the pH range of 2.9-9.2. The proposed sensor also exhibits a fast response time of < l0 s. The detection limit of the proposed sensor is 4.8 × 10^− 6 M, and it can be used over a period of 10 weeks without significant changes in its response. Furthermore, the electrode showed high selectivity toward Nd(III) ion respect to all other lanthanide ions tested. The practical utility of the sensor was demonstrated by using it as an indicator electrode in the potentiometric determination of Nd(III) ions in certified reference material and spiked water samples.     

Thermoeconomic optimization of a shell and tube condenser using both genetic algorithm and particle swarm

This paper presents a thermoeconomic optimization of a shell and tube condenser, based on two new optimization methods, namely genetic and particle swarm (PS) algorithms. The procedure is selected to find the optimal total cost including investment and operation cost of the condenser. Initial cost includes condenser surface area and operational cost includes pump output power to overcome the pressure loss. Design parameters are tube number, number of tube pass, inlet and outlet tube diameters, tube pitch ratio and tube arrangements (30, 45, 60 and 90°). Therefore, shell diameter should be selected less than 7 m, tube length should be less than 15 m, and ratio of diameter to tube length should be in the range of 1/12 to 1/3. In addition, it is found that GA provides better results for computer CPU running time, compared to PS algorithm. Finally, a sensitivity analysis of design parameters at the optimal point is conducted. Results show that an increase in the tube number leads to decrease in the objective function first then it leads to a considerable increment in objective function.     

Switched diversity approach for multireceiving optical wireless systems

A number of existing spatial diversity schemes have been shown to improve the performance of optical wireless communication systems in diversity-rich environments. Among all, switched diversity has low complexity and is simple to implement. In this paper, an innovative spatial diversity scheme based on switched diversity is proposed. The scheme, namely switch-to-dominant combining, contributes to a higher bit error rate (BER) performance when compared to conventional switched diversity schemes, including switch-and-stay and switch-and-examine diversity. The optical multireceiver wireless system operates in a spatially correlated and lognormally distributed fading channel. Analytical analyses are conducted to demonstrate BER and processing load performance offered by the new scheme and compare them to available schemes, i.e., conventional switched combining and selection combining.     

Physical properties of Bi2 (Te,Se)3 and Bi2Se1.2Te1.8 prepared using solid-state microwave synthesis

Bi₂(Te, Se)₃ and Bi₂Se_1.2Te_1.8 bulk products were synthesised using standard solid-state microwave synthesis. The Bi₂(Te, Se)₃ and Bi₂Se_1.2Te_1.8 were then deposited thermally onto glass substrates at a pressure of 10^? 6 Torr. The structure of the samples was analysed using X-ray diffraction (XRD), and the powders and thin films were observed to be polycrystalline and rhombohedral in structure. The surface morphology of the samples was determined using scanning electron microscopy (SEM). From the measurements of optical properties, the energy gap values for the Bi₂Te₃, Bi₂Se₃, and Bi₂Se_1.2Te_1.8 thin films were 0.43, 0.73, and 0.65 eV, respectively.     

Theoretical study of structural,electronic and thermal properties of Zn1−xBexS ternary alloy

The structural, the electronic and the thermal properties of Zn_1?xBe_xS ternary alloy have been calculated using the full-potential linearized-augmented plane wave (FP-LAPW) method. The exchange and correlation potential is treated by the generalized-gradient approximation (GGA) using the Perdew–Burke–Ernzerhof (PBE) parameterization. Moreover, the Engel–Vosko GGA formalism is also applied to optimize the corresponding potential for band structure calculations. The ground state properties such as lattice constants and bulk modulus are in good agreement with numerous experimental and theoretical data. The thermodynamic stability of this alloy was explained by calculating the phase diagram. The quasi harmonic Debye model, using a set of total energy versus volume calculations obtained with FP-LAPW method is applied to study the thermal and vibrational affects. Temperature effect on the lattice parameter, thermal expansion coefficient, heat capacity and Debye temperature is determined from the non-equilibrium Gibbs function.     

Quantitative monitoring of terbium ion by a Tb3+ selective electrode based on a new Schiff's base

Solution study showed N,N′-bis(5-nitrosalicylidene)-2-aminobenzylamin (L) trends toward Tb³⁺ ion. Then, it was used as a suitable ionophore in construction of terbium ion selective electrode. The electrode with composition of 30% PVC, 65% solvent mediator (NB), 3% ionophore (L) and 2% anionic additive (NaTPB) shows the best potentiometric response characteristics. It displays a Nernstian behavior (20.1 mV decade^?1) over the concentration range 1.0 × 10^? 6 to 1.0 × 10^? 2 mol L^?1. The detection limit of the electrode is 6.3 × 10^? 7 mol L^?1. It has a very short response time (~ 10 s) and a useful working pH range of 2.6–9.4 for at least 2 months. The proposed membrane sensor shows excellent discriminating ability towards Tb³⁺ ions with regard to several alkali, alkaline earth, transition and heavy metal ions. To investigate the analytical applicability of the sensor, it was successfully applied to the determination of terbium in certified reference material.