By employing atomistic simulations based on an empirical potential, we study the collision dynamics of low-energy carbon ions impinging on single-walled carbon nanotubes. We investigate the energy transferred from the incident carbon ions to the target atoms in the nanotubes. We find that the lowest incident energy needed for the primary knock-on atom to be permanently displaced from its original location is 18 eV, and for the secondary knock-on atom to escape out of the nanotube is estimated to be 28 eV. Moreover, we find that the incident threshold energy strongly depends on the diameter of the nanotube and its chirality, and saturates towards the corresponding value in graphene as the tube diameter increases. Furthermore, a single vacancy and an adatom defects are obtained after optimization using the ab-initio calculations.

Nanocrystalline Cd0.8Zn0.2S thin films were prepared by chemical-bath-deposited method and the effect of time on the properties of Cd0.8Zn0.2S thin films was studied. The X-ray diffraction (XRD) patterns show that the synthesized films have a cubical (zinc blende) phase. The mean crystallite size and the internal lattice strain were calculated. Atomic force microscopy (AFM) studies showed that the surface roughness of the films increase with increasing thickness. The optical constants of Cd0.8Zn0.2S films were determined and the analysis of the result showed that Cd0.8Zn0.2S thin films have direct transition and the values of energy gap indicates quantum confinement effect.

The development of CCS (carbon capture and storage) currently faces numerous problems and particularly the precipitation of salts induced by the drying of the porous medium during injection of carbon dioxide in deep saline aquifers. This precipitation has several consequences, and particularly the creation of a crystallization pressure which can have an important mechanical impact on the host rock. Literature on crystallization pressure is one century rich of experimental and theoretical works. However, applications have been performed in the field of civil engineering and building science only, and, despite they are of paramount importance in the context of CCS, studies about this phenomenon in deep reservoir conditions are currently lacking. In this paper, we retrieve the classic crystallization pressure equation within the framework of geochemistry and present its explicit form of dependence with temperature, pressure, and composition. Evaluation of the crystallization pressure has then been proceeded considering the injection conditions and a sketch of in-pore crystallization process. The evolution of the local stress transmitted to a crystallized pore wall is found to be strongly related to the petrophysical properties of the medium and to the injection temperature of the carbon dioxide under the assumption of constant salt concentration during the precipitation process. Values differ strongly with the considered mineral, depending particularly on the solubility, and can reach in some conditions 165 MPa, making crystallization pressure a major factor in the mechanical behavior of the aquifer.

Indium phosphide semiconductor materials (InP) have various applications in the field of semiconductor optoelectronics because of its advantages. But the making of this material is difficult due to the very weak chemical activity of In element. In this report we present a simple method to synthesize InP nanocrystals from inorganic precursors such as indium chloride (InCl3), yellow phosphorus (P4), reduction agent NaBH4 at low temperature with the aid of ultrasound. Structural, morphological and optical properties of the formed InP nanocrystals were examined by transmission electron microscopy (TEM), X-ray diffraction (XRD), energy dispersed X-ray analysis (EDS), Raman scattering, absorption and photoluminscence (PL) spectroscopy. After the surface treatment of InP nanocrystals with liquid hydrofluoric (HF) acid, the luminescence spectra have an enhanced intensity and consist of the peaks in the region from 500 nm to 700 nm. The intensity of these peaks strongly depends on the concentration and etching time of HF.

Magnetic nanoparticles FexPd100−x (x = 42, 50, 55, 60, 63) with small size of around 5–10 nm were prepared by sonochemistry from palladium acetate and iron acetate. The compositions x can be controlled by changing the ratio of the above precursor chemicals. Under the effect of annealing at various temperatures from 450 °C to 650 °C, structure change was observed and samples show hard magnetic properties with high coercivity up to 2.1 kOe. Magnetic properties of samples were then systematically discussed in dependence of x and annealing temperatures.

The mechanically activated self-propagating high-temperature synthesis (MASHS) technique and the mechanically activated annealing process (M2AP) were used to produce NiAl intermetallic compound. Rietveld analysis of X-ray diffraction data was used to characterize the mechanically activated powders, MASHS and M2AP end-products. Two-phase (B2+L12) nickel aluminide intermetallic compounds were synthesized by the mechanically activated volume combustion synthesis (MASHS). A single phase B2 NiAl was formed when mechanically activated annealing process (M2AP) was performed. Starting from a mixture of elemental pure powders, both M2AP and MASHS milling processes lead to nanostructured powders. Structural analysis deduced from the Rietveld refinement of X-ray diffraction patterns of NiAl compounds synthesized by SHS after a milling of 6 h show the formation of β-NiAl phase with a cell parameter a = (0.2885 ± 1.2618 × 10−4) nm. The average crystallite size is D = (44.6421 ± 2.4263) nm and the microstrains values are close to those of metallic alloys τ = (0.2142 ± 1.6186 × 10−2)%. Finally, scanning electron microscopy (SEM) was carried out to characterize the microstructure of end-products.

ZnAl2O4:Cr3+, Tb3+ powders with different dopant contents have been synthesized by sol-gel method using the following precursors: zinc nitrate (Zn(NO3)2), aluminum nitrate (Al(NO3)3), terbium nitrate (Tb(NO3)3), chrome nitrate (Cr(NO3)3), and citric acid. The effect of the Cr3+, Tb3+ concentration and heat-treating temperature on structural and optical properties of the synthesized samples has been studied.

In electromagnetic compatibility, scattering problems are defined in an infinite spatial domain, while numerical techniques such as finite element methods require a computational domain that is bounded. The perfectly matched layer (PML) is widely used to simulate the truncation of the computational domain. However, its performance depends critically on an absorption function. This function is generally tuned by using case-dependent optimization procedures. In this paper, we will present some efficient functions that overcome any tuning. They will be compared using a realistic scattering benchmark solved with the Discontinuous Galerkin method.

The objective of this study was to evaluate in situ structural and thermal changes of dental restorative materials at periodical time intervals. The commercial materials included zinc oxide eugenol (ZOE), zinc phosphate type I (ZnPO4), glass ionomer cement type II (GIC) and resin-based nano-omposite (Filtek Z350 XT). These materials were processed according to manufacturer’s instructions. For the structural analysis Fourier transform infrared spectroscopy (FTIR) was used at high resolution. TGA was used to evaluate thermal weight-loss. The FTIR spectra were collected at periodic time intervals. FTIR spectra showed that with time passing all materials exhibited an increase in peak intensities and a new appearance of shoulders and shifting of peaks for example, ZnPO4 (P-O), ZOE (C═O, C═N, C-O-C), GIC (COO–, C-H, Si-OH), composites (C═O, C═C, C═N, C-N-H). The peaks were replaced by bands and these bands became broader with time interval. Composites showed a degree of conversion and new peaks corresponded to the cross-linking of polymer composites. TGA analysis showed that significant changes in weight loss of set materials were observed after 24 h, where ZOE showed continuous changes in thermal degradation. The spectral changes and thermal degradation with time interval elucidated in situ setting behaviour and understanding of their bonding compatibility with tooth structure and change in relation to time.

In this article, we report on the design and construction of an in situ break-junction sample holder for transmission electron microscopy. The holder is based on the differential-screw mechanism. The technical details and a comprehensive consideration to all relevant critical issues surrounding the instrumentation procedure are presented. An application of the newly developed instrument is demonstrated using the example of a micro-scale gold wire. We also provide a detailed discussion on the challenges involved and the pitfalls to avoid in developing similar in situ holders.

The present paper addresses the computation of force fields inside permanent magnets that are used in many magnetic systems. The aim is to stress that magnetic behavior is not sufficient when the B-H constitutive law depends on the mechanical deformation. A full knowledge of B and H may not be enough to unambiguously compute forces. Using two expressions of magnetic energy, both admissible and giving the same B-H relationship, an application of the virtual power principle leads to two distinct force distributions. To prove this, thorough computations are performed: depending on the chosen expression huge differences on deformations are obtained.

Mesoporous MgO has been synthesized in the presence of the neutral block co-polymer surfactant Pluronic F127. The characterization of synthesized material was carried out by mean of X-ray diffraction (XRD), scanning electron microscope (SEM) and Brunauer-Emmett-Teller technique (BET). The obtained MgO exhibited a value of the surface area of 157 m2/g and showed a narrow pore size distribution centered at 4.3 nm. The phenomena and gas evolved during calcinations have been investigated by thermogravimeter-mass spectrometer (TG-MS). During the calcinations, the precursor Mg(OH)2 was converted to MgO with a mass loss of 29% and with the formation of H2O (>60% of the gas evolved). The desorption of CO2 and a small amount of CO and/or N2 which were adsorbed from air on the surface of Mg(OH)2 were also observed. No organic compounds were found which indicated that F127 was completely removed by Soxhlet extraction.

Mixing and chaotic advection are studied in a liquid electrolyte set in motion by an electrical current passing through the fluid which is perpendicular to a magnetic field (Laplace force). Since the characteristic length in this system is very small, the inertia terms are negligible and the fluid motion is governed by the Stokes equations. Chaotic advection can occur in this flow if the potential between two electrodes is modulated time-periodically. Two tools have been implemented to characterize mixing in this flow. Poincare sections are plotted in order to distinguish between regular and chaotic regions and the advection of a blob of dye injected into the liquid is calculated and successfully compared to experiments. This very small device is shown to be an effective fluid mixer.

The electrical contact resistance of a vertical binary contact between stainless steel balls with a low mechanical load was investigated. Using a statistical approach, we measured the voltage at which the dielectric breakdown occurs within a thin surface oxide layer and the distribution of the contact resistance. Electrical load-bearing conduction through a thin insulating layer was found to occur through two possible sequential processes. In both cases, once a conduction path is formed, the melting of bridges as in conventional contact theory is involved. This suggests that conduction through an oxide layer with a low mechanical load depends mainly on breakdown-induced bridges. Furthermore, the distribution of such path’s resistance shows the log-normal distribution with a long tail toward high resistance.

This study focuses on the comparison of two different types of EEG electrodes (the first B10-S-150 Ag/AgCl sintered ring electrode with 1, 5 mm touch proof safety socket and 150 cm heavy-duty lead wire and the second, B12-LS-100 Ag/AgCl sintered FE-electrode with 100 cm light-duty lead wire and 1, 5 mm touch proof safety socket with 5 kΩ resistor near sensor) used in the EEG/fMRI method in 3T MRI scanner. We compared these electrodes by their specific absorption rate (SAR) simulation values and the temperature change calculated by PRF method. The experimental setup of the study is described as follows: a phantom is prepared and the electrodes are placed on it. Then, a simulation for SAR values is realized. The temperature change is calculated by MR thermometer. As a result of this study, Ag/AgCl pin electrode is better to be use in EEG/fMRI; because the measured temperature change is expected to be low.

In this paper, Schlieren photography technique has been applied for the visualization of the pressure field of a single-shot underwater pulsed discharge. A needle-to-plane electrode configuration submerged in distilled water was used. The detailed time- and space-resolved images of both streamers and pressure waves were captured. As a result, several phenomena, such as the phase change prior to the initiation of the discharge, primary and secondary streamers propagation, shock wave generation, and the bubble formation, were observed. From these observations, a scenario of multiple events from prebreakdown to post-discharge was proposed. The gas bubbles generated in discharge were used to visualize the electrohydrodynamic flow induced by the discharge.

For liquid droplets of sub-micrometer dimensions, the study of wetting properties (quantified by contact angle, disjoining pressure, spreading coefficient, etc.) is possible using the relatively new technique known as scanning polarization force microscopy (SPFM). This non-contact scanning probe microscopy technique was successfully implemented in our laboratory in order to study the wetting properties of glycerol and sulfuric acid on the surface of highly oriented pyrolytic graphite (HOPG) and glycerol on aluminum film deposited on mica. An AC polarization bias of 3 V at 3 kHz frequency was applied between a conductive atomic force microscope tip and the substrate. The resulting polarization force was measured with high accuracy, allowing non-contact topography profile measurements of liquid micro- and nanodroplets. The dependence of the contact angle on droplet height was determined in order to calculate the values of the spreading coefficient and the disjoining pressure between the liquid and substrates. The calculated potential energies give disjoining pressure values of ∼0.4 atm for glycerol on HOPG, ∼0.47 atm for glycerol on aluminum and ∼13 atm for H2SO4 on HOPG. In the case of H2SO4 on HOPG the strength of the force appears to be thirty times bigger than that for glycerol on HOPG and aluminum.

The aim of this work is to model the interaction of L-band electromagnetic waves with coastal breaking sea waves. The breaking sea waves’ profiles are generated using the desingularized technique and the electromagnetic waves scattering is computed using the high-order method of moments (HO-MoM) combined with non uniform rational basis spline (NURBS) geometry. Our study mainly focuses upon the electromagnetic waves behavior in the crest and the cavity of breaking sea waves.

We study the solutions and bifurcations of the Jeffcott rotor with a rubbing effect. The model of horizontal rotor possesses such nonlinear effects as inertia, dry friction, and contact loss between the rotor and stator. By the exceeding of the rotor-stator radius clearance, the rotor can penetrate into the limiting rubbers with a fractional power in the restore force. The system response is analyzed by a bifurcation diagram. The specific cases are additionally clarified by means standard methods and quantified by the test 0-1 which is sensitive to chaotic behaviour.