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Currently, nanostructures such as nanobeams, nanomembranes and nanoplates have been a hot area of research triggering. The contribution of this research article deals with both the effect of the free and dynamic vibration of a nanobeam as well as the use of the FGM material by integrating the piezoelectric effect. In fact, incorporating the initial stress for a nanoscale beam has not been considered yet. This paper displays an analysis of dynamic and free vibration of power-law functionally graded piezoelectric materials (FGPM) subjected to thermal-electro-mechanical loads with initial stress. The model was resolved based on nonlocal Timoshenko beams theory. The dimensionless fundamental frequency gradually improved with the new configuration of the FGPM nanobeam by 5% compared to the FGM nanobeam. The accuracy of this model is highlighted via numerical examples for different boundary conditions. To solve the governing equations, the polynomial differential quadrature method (PDQM) was elaborated and resolved numerically using MATLAB. For various configurations of the FGPM nanobeams, the effect of scaling parameters, volume fraction and slenderness ratios were discussed. In addition, for different edge conditions, variations of the first four frequencies with volume fraction indices and for different scaling parameters were set forward. This study corroborated that the power exponent, nonlocal parameter, slenderness ratio and thermo-electro-mechanical loads have significant effects on the dimensionless frequencies of various FGPM nanobeams. The present work provides an enlightening as guideline for the draft of a nanoscale beams based thermo-electro-mechanical actuators.

The mixed vanadium-titanium oxo-alkoxy (VTOA) nanoparticles were synthesized via sol-gel method in a chemical reactor with ultra-rapid micromixing. The nucleation and growth kinetics and particles size, followed by the static/dynamic light scattering methods, were quite different from those of pure oxo-alkoxy titanium (TOA) and vanadium (VOA) species. It was shown that the TOA species appear first and serve to be centres of attraction for hydrolysed VOA species at the nucleation stage. However, at the vanadium content above 20 mol% large VOA species imprison sub-nucleus TOA species prohibiting the nucleus appearance. The model analysis of the VTOA induction kinetics validated a significant increase of the nucleus size with an increase of the precursor concentration. The results support a new paradigm of the sol-gel process describing profound restructuring of the oxometallic species during assembling at the nucleation stage.

Free vibration of sandwich nanobeam is presented in this chapter. The upper and lower sheets are modeled considering Euler-Bernoulli beam formulation and for the core the Timoshenko beam formulation is used taking into account the shear effect. The Non-dimensional procedure is used in order to simplify the analysis of governing equations. The sandwich nanobeam is modeled using Generalized Differential Quadrature (GDQ) method. The influence of the nonlocal parameter (NP) on the first three natural frequencies of Simply Supported - Simply Supported (SS-SS) sandwich nanobeam is discussed . For different edge conditions, mode shapes of the present sandwich nanobeam are discussed. It can be noted that deflection shapes are touched by increasing the NP. For the C-C sandwich nanobeam, natural frequencies are higher than the SS-SS one. Variation of the nonlocal parameter (NP) on the frequencies of the sandwich nanobeam is also investigated for different length . It can be observed that the first frequency have not an important effect for different length, for that, we move to present the second frequency. With increasing the NP the natural frequency decreases clearly. Explication can be regarded as the dispersive behavior of frequencies. The present model can be used as guideline for applications of sandwich nanostructures.

V-TiO2 photocatalyst with 0 ≤ V ≤ 20 mol% was prepared via the sol–gel method based on mixed oxide titanium–vanadium nanoparticles with size and composition control. The mixed oxide vanadium–titanium oxo-alkoxy nanonoparticles were generated in a chemical micromixing reactor, coated on glass beads via liquid colloid deposition method and underwent to an appropriate thermal treatment forming crystallized nanocoatings. X-ray diffraction, Raman, thermogravimetric and differential thermal analyses confirmed anatase crystalline structure at vanadium content ≤ 10 mol%, with the cell parameters identical to those of pure TiO2. At a higher vanadium content of ~20 mol%, the material segregation began and orthorhombic phase of V2O5 appeared. The crystallization onset temperature of V-TiO2 smoothly changed with an increase in vanadium content. The best photocatalytic performance towards methylene blue decomposition in aqueous solutions under UVA and visible light illuminations was observed in V-TiO2 nanocoatings with, respectively, 2 mol% and 10 mol% vanadium.

This paper reports an investigation on thermo-electro-mechanical vibration of graphene/piezoelectric graphene/piezoelectric/graphene sandwich nanobeams. Based on the nonlocal elasticity theory, Timoshenko beam theory and Hamilton's principles, the governing equations are developed and solved using generalized differential quadrature (GDQ) method. The effects of the nonlocal parameter, external electrical voltage, temperature change and axial force on vibration of graphene/piezoelectric/graphene sandwich nanobeams are examined. The performance and the accuracy of the presented model are highlighted through numerical examples with different boundary conditions. This study reports that the nonlocal parameter and thermo-electro-mechanical loadings have important effect on the natural frequencies and the deflection mode shapes of the graphene/piezoelectric/graphene sandwich nanobeam. The present work can serve as guideline for the design of a nanoscale graphene/piezoelectric/graphene beams based electromechanical resonator sensors.

Chemical reactors with micromixing of liquids play an important role in the chemical engineering process leading to new materials with an improved functional response. We show that the liquids injection conditions correspondent to low Damkohler numbers may turn from the common liquid phase to unusual biphasic liquid/vapour fluid flow due to the cavitation phenomenon. We propose in-situ physical measurements of the cavitation threshold in the exocentric T-mixer using light scattering method. Numerical calculations support the assignment to cavitation and show its critical relation to the T-mixer geometry.

The mixing of fluids at micro-scale is one of the most important operations in the development of micro-fluid systems for applications in chemical and biochemical engineering, biomedical systems. Attaining rapid mixing is a challenging task because mixing mainly relies on molecular diffusion across the interface of the fluid stream in micro channels. The geometry of the T-mixer with non-coaxial inputs in which the reagents are mixed can have a great influence on the distribution of nanoparticle products (on the preparation of homogeneous and monodisperse nanoparticles). The T-mixer is designed in such a way that the entering jet forms a vortex and generates a turbulent swirling flow: the fluid velocity profile presents an instant formation of a vortex in the fluid contact area. The vortex package consists of elementary vortices of both reagents, the size of which depends on the amount of energy injected into the system. This article focuses on the experimental validation of our numerical model of the T-mixer, by measuring the height (Zi) for obtaining this micro-mixing. For the numerical model, we used the Computational Fluid Dynamics (CFD) to simulate fluid flow in the T-mixer with the k-e turbulence model using Ansys Fluent software. Numerical and experimental values of Zi mixing converge.

Misfire faults caused by the malfunction of single cylinder increases the emission level and fuel consumption of internal combustion. So, the detection of misfire is required. In this paper, we studied the effect of misfire on the dynamic response of the crankshaft in order to propose a method based on the torsional vibration signal of crankshaft acceleration for misfire detection. For this, a torsional model of a four cylinder crankshaft excited by the acyclism phenomena is proposed. The external forces are the inertia and gas torque of each engine cylinder. The equations of motion are obtained by using Lagrange method and computed with the help of Newmark algorithm. Three kind of misfire faults of the first cylinder are modeled through the gas pressure variation inside this cylinder and induced in the excitation torques: missing combustion, pre-ignition and delayed ignition. After that, the vibration responses of the crankshaft is computed and processed in order to highlight the effect of misfire defects on the crankshaft vibration signals. In fact, appearance of sidebands around the acyclism frequency in the frequency domain allow detecting the misfire and the time acceleration signal allows identifying the kind of defect.

In Europe, rapeseed is a renewable raw material which has been widely used for the production of biodiesel by various processes. The transesterification reaction of rapeseed oil with ethanol to biodiesel in supercritical fluid conditions was investigated using several heterogeneous catalysts and preliminary ultrasonic emulsification of the reaction mixture, to run the reaction at mild conditions. Phase equilibrium of fatty acids in supercritical ethanol was study to determine the operating condition in supercritical states. Transesterification experiments were carried out under a pressure of 30 MPa, with ethanol to oil molar ratio (in the range of 12:1⿿20:1), temperature (623 K to 653 K), and the catalyst loading level and type were the main parameters. The most important characteristics of Al 2 O 3 support catalyst and the impregnation method with aqueous solution of metal nitrates are also described. Yields of Fatty Acids Ethyl Ester (FAEE) are reported for different ZnO/Al 2 O 3 , MgO/Al 2 O 3 , SrO/Al 2 O 3 catalysts in different experimental conditions. The higher yield of 97.46% was obtained under the optimal conditions 623 K, 30 MPa, 12:1 ethanol/FAEE molar ratio, with SrO/Al 2 O 3 (2 wt.% SrO) impregnated catalyst.

The decomposition of acetaldehyde was investigated in a plasma-catalytic reactor. The gold-based catalysts were obtained by growing Au nanoparticles on silica beads or plates previously coated by a titanium oxo-alkoxy monolayer. The characterization of the synthesized catalysts was carried out by SEM, AFM and UV–Visible spectroscopy. Below an exposure time to UV of 20 min, a homogeneous surface coverage by the relatively small gold nanoparticle (R

We report on the effect of mixing on the morphology of ultrafine zinc oxide nanoparticles synthesized via a polyol process using zinc acetate and water in a diethylene glycol medium. Three mixing strategies were considered: stirred batch, T-mixer, and impinging free jets. The particle granulometry was accessed using the transmission electron microscopy and x-ray diffraction methods. The nanoparticle size and polydispersity decreased with an increase in the local dissipated energy. In particular, the polyol process conducted in the same chemical environment at 353 K did not lead to the observation of nanoparticles in the stirred batch reactor but resulted in unconventionally small 6-nm particles in the T-mixer and impinging jet configurations. This result is apparently related to the micromixing eddy geometry described by the Kolmogorov length. The hydrodynamic flow patterns and energy dissipation were obtained from computational fluid dynamics simulations, which are essential in the design, optimization, and scale-up of the polyol process. © 2015 American Institute of Chemical Engineers AIChE J, 61: 1708–1721, 2015

The efficiency of the process coupling a dielectric barrier discharge and a fluidized nanostructured silver-based bed for the degradation of a model pollutant (acetaldehyde CH 3 CHO) is presented. The deposition of silver nanoparticles has been realized by photocatalytic reduction of Ag + ions in aqueous solution of silver nitrate salt on TiO 2 nanoparticles deposited on SiO 2 beads. In the first part, the efficiency of the plasma alone process is discussed, in terms of pollutant removal and CO and CO 2 production. The main pathways of pollutant degradation and CO x production are discussed. In the second part, CH 3 CHO removal as well as CO x production is studied as a function of the photocatalytic reduction time of Ag + ions, which is related to the deposited silver mass. Finally, pollutant removal pathways, including homogeneous chemistry in the plasma phase and heterogeneous chemistry on the surface, are discussed.

We report on a new method of preparation of AgN-TiO2 nanoparticulate coatings with stable and highly reproducible morphology. The silver nanoparticles are grown on monolayer titanium-oxo-alkoxy nanoparticulate coatings by silver ions reduction at UV-A light illumination. Their size and surface number density increase with the irradiation time. The AFM and high-resolution SEM and TEM measurements of height (h) and lateral size (D) of the silver nanoparticles show that their shape approaches spherical segment with h/D = 1/4 at long irradiation times. The size correspondent to the maximum of the particles size distribution curve tends to D = 12 nm with half width at full-maximum ΔD = 4 nm. The evaluation of the deposited silver mass results in the quantum yield of the deposition process close to 100% at the process beginning and the atomic surface density of NAg = 1.25 × 107 at/μm2 at the process saturation. The absorption spectra of the surface plasmon shift from 425 to 525 nm. The spectra are successfully ...

Nucleation and growth of zirconium-oxo-alkoxy (ZOA) nanoparticles were studied in a sol–gel process in n-propanol solution at a hydrolysis ratio H between 1.0 and 2.7 and zirconium-n-propoxyde precursor concentrations between 0.10 and 0.15 mol l−1. The chemical transformations were conducted in quasi-perfect micromixing conditions (Damkohler number Da ≤ 1) and the nanoparticle size evolution was monitored in situ with the light scattering method. The size of primary nanoparticles (nuclei) 2R0 = 3.6 nm was found to be almost independent of the preparation conditions. A remarkable similarity with the titanium-oxo-alkoxy (TOA) nanoparticles was observed. In particular, both systems show the induction stage of the sol–gel growth for a hydrolysis ratio H > 2.0 and stable oxometallate units for H ≤ 2.0. However in contrast to TOA, no stable hierarchical ZOA units (clusters) with R0 ≥ R ≥ 1.0 nm were observed, which makes this system less stable against aggregation, leading to polydispersed nanoparticles.

A comparative evaluation of the antibacterial effect of silver in the form of nanoparticles and Ag+ ions was performed. Silver nanoparticulate coatings of stable and reproducible morphology were prepared on monolayer size-selected titanium-oxo-alkoxy nanoparticles deposited on glass substrates. The coatings exhibit a strong antibacterial activity towards Escherichia coli K12 AB 1157 and suppress biofilms formation. This activity is mainly related to the Ag+ ions release into aqueous solutions in dark. The deposited silver mass ~1 μ g.cm-2 is smaller compared to that of Ag+ ions and nanoparticles generally reported for inhibiting Escherichia coli. The synergetic effect of the deposited nanoparticles and Ag+ ions can be suggested.