Dynamics of inertial dewetting

The dynamics of fast dewetting is considered in both unidirectional and axisymmetric dewetting cases. The analysis provides the front and dewetting velocities along with the wave speed (Froude number larger than 1) based on the momentum and continuity equations. The model does not require any fitting parameter. In the unidirectional case, the present model results are direct, while in the axisymmetric case, a simple trial-and-error procedure is required. Culick’s law (derived for the rupture of soap films and extended to unidirectional fast dewetting velocity by other investigators) is found to be a limiting case for both the dewetting and front velocities at small values of the film thickness for both unidirectional and axisymmetric dewetting geometries. The proposed model results show favorable agreement with published experimental front velocity data at large values of the film thickness.     

Investigation of elastic constants of polymer/nanoparticles composites using the brillouin spectroscopy and the mechanical homogenization modeling

A numerical model using homogenization techniques is proposed to simulate the evolution of elastic properties of nanocomposite polymer‐nanoparticles, depending on the concentration of nanoparticles and the rigidity of the particle–matrix interface. To validate this model, it was confronted to several physical systems having different interface behavior, the nanocomposite systems: poly(vinylidene fluoride trifluoroethylene)/Al₂O₃ (alumina nanoparticles incorporated into copolymer of vinylidene difluoride and trifluoroethylene to form nanocomposite), PMMA/CNT (carbon nanotube/poly(methyl methacrylate) composite) and PMMA/SiO₂ with nanoparticles with or without surface treatment of silanization. For all these systems, the Young's modulus (nanoparticles and matrix) has been obtained experimentally from the elastic modulus C₁₁ obtained by Brillouin spectroscopy. These macroscopic measurements coupled with the theoretical model allow a multiscale approach of the elastic behavior of nanocomposite systems, providing information on the global elastic properties of polymer‐nanoparticle material, and also indications about the strength of physical and chemical bonds between the nanoparticles and the matrix. Our results validate the hypothesis of the crucial role of the interface module, provided by numerical simulation which shows that incorporation of nanoparticles may lead to a strengthening or a weakening of the matrix. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers.     

产业用纺织品的市场趋势

多方面的研究证实,产业用纺织品市场将继续高速增长,这些研究的作者们对于价格稳定性持乐观态度,并预期利润保持不变。叙述了2010年产业用纺织品增长15％～27％的推动力（图1～图3）。     

Antibacterial activity and chemical composition of 20 Eucalyptus species’ essential oils

The essential oils of twenty Eucalyptus species harvested from Zerniza and Souinet arboreta (North West and North of Tunisia), were screened for their antibacterial activities by the agar disc diffusion method. Eighteen major compounds, identified by GC and GC/MS, have been retained for the study of the chemical and biological activity variability. The main ones were 1,8-cineole followed by α-pinene, p-cymene, borneol, cryptone, spathulenol, viridiflorol and limonene. The chemical principal components analysis identified 10 chemotypes, however that of the inhibition zone diameter (izd) of growth bacteria separated 5 groups of Eucalyptus oils, characterised by their antibacterial inhibition ability. The most sensitive strain was the Gram positive Staphylococcus aureus with that of E. odorata oil (16.0 ± 1.0 mm izd), while the most resistant bacteria was Pseudomonas aeruginosa. Some correlation between the amount of 1,8-cineole, p-cymene, α-pinene, or of cryptone and the antibacterial activity were observed.     

Magnetohydrodynamics stability of a rotating flow with heat transfer

We study the magnetohydrodynamic stability of an axisymmetric rotating flow in a cylindrical enclosure filled with a liquid metal (Pr = 0.015), having an aspect ratio equal to 2, and subjected to a vertical temperature gradient and an axial magnetic field. The finite volume method is used in order to solve the equations of continuity, momentum, energy, and electric potential. Without magnetic field, the critical Reynolds number is a decreasing function of the Richardson number owing to the destabilizing contribution of natural convection. In the presence of a vertical magnetic field, the flow stability is preserved for higher values of the Reynolds number. The stability diagram which is established shows the dependence of the critical Reynolds number with the increase of the Hartmann number, Ha, for various values of the Richardson number. This study confirms the possibility of stabilization of a liquid metal flow in mixed convection by application of an axial magnetic field.     

Novel Natural Based Diazepines as Effective Corrosion Inhibitors for Carbon Steel in HCl Solution: Experimental,Theoretical and Monte Carlo Simulations

Three new heterocyclic diazepines (CC–diCl, CC–Cl and CC–F) were synthesized for the first time from the natural product curcumin and evaluated as non-toxic corrosion inhibitors for carbon steel (CS) in 1 M HCl. The evaluation was carried out using electrochemical impedance spectroscopy, polarization curves (PDP) measurement, weight loss (WL) and scanning electron microscopy studies. The molecular modeling methods: density functional theory calculations and Monte Carlo simulations were performed to obtain a good insight into the inhibition process. Results obtained from electrochemical techniques and WL tests revealed that, the studied diazepines were effective corrosion inhibitors for CS in the tested medium. Among the evaluated diazepines, CC–diCl showed the highest efficiency. According to the PDP results, the diazepines behaved as mixed-type (cathodic and anodic) inhibitors. A complete thermodynamic study was also performed on the diazepine with the highest efficiency CC–diCl to gain a better understanding of the inhibition process. The adsorption of the diazepines onto CS surface obeyed a Langmuir adsorption isotherm. A good correlation was obtained between the molecular modeling studies and inhibition efficiency (IE%) of the tested diazepines.     

Influence of the deposition conditions on the crystallographic structure and the GaAs refraction index

An experimental study of the influence of deposition conditions of GaAs thin films growth, by radio frequency sputtering method, on the structure and the refraction index has been performed. The X-ray diffraction and spectrophotometer results, with different deposition conditions, are reported.The refraction index depends on the structure, which also depends on four deposition parameters, namely, the self-bias voltage, V_p, the argon pressure, P_Ar, the target-to-substrate distance, d, and the substrate temperature, T_s. Hence, it has been observed that, the index refraction of the films decreases with V_p and T_s and increases essentially with P_Ar.     

A comparative study of tartrazine degradation using UV and solar fixed bed reactors

The fixed bed reactor was combined with a solar photoreactor and UV lamp reactor. This hybrid photoreactor used a heterogeneous photocatalysis process (TiO₂/UV) as a tertiary treatment for the degradation of tartrazine dye in water. The solar reactor removed almost all organic compounds from the wastewater. Photocatalysis was optimized using a parametric study to improve the influence of different parameters on the degradation efficiency. Color removals when using solar, UV lamp and hybrid reactors present 99%, 30%, and 99%, respectively. Tartrazine removal kinetics followed a pseudo-first order model. The hybrid solar and UV lamp system combination was a feasibility choice for removing both dyes from wastewater.     

Smith Predictor Based Fractional‐Order‐Filter PID Controllers Design for Long Time Delay Systems

In this paper, an original model‐based analytical method is developed to design a fractional order controller combined with a Smith predictor and a modified Smith predictor that yield control systems which are robust to changes in the process parameters. This method can be applied for integer order systems and for fractional order ones. Based on the Bode's ideal transfer function, the fractional order controllers are designed via the internal model control principle. The simulation results demonstrate the successful performance of the proposed method for controlling integer as well as fractional order linear stable systems with long time delay.