Original Setup Research Articles

Characterization of soil stiffness anisotropy at small strains based on phase velocities of shear waves measured by novel testing apparatus

For the characterization of soil stiffness anisotropy at small strains and the calculation of soil elastic constants derived from the cross-anisotropic model, it is important to obtain stress wave phase velocities of soils in both principal and oblique directions. This study developed an original eight-prismatic shape apparatus equipped with disk-shaped shear plates to measure shear (S-) wave phase velocities (Vphase) in multiple directions, and four granular materials of various shapes were tested by this apparatus under isotropic confinement. Experimental results confirm the capability of the new apparatus and reveal that both S-wave propagation and oscillation directions are sensitive to soil inner fabric, i.e., Vs changes with the variation of either S-wave propagation or oscillation direction. Based on the experimental observations, it is suggested to keep the same S-wave oscillation direction when measuring Vs in multiple propagation directions so that the corresponding shape of the S-wave surface (polar plots of Vs in arbitrary propagation directions) is more precise to reflect the small-strain stiffness anisotropy of soils.

A Summative Assessment of the Pattern-Cutting Task in Laparoscopic Box Trainer using Color Tracking and Fuzzy Logic

In Minimally Invasive Surgery (MIS), surgeons should acquire many skills before carrying out a real operation. The Fundamentals of Laparoscopic Surgery (FLS) tasks are currently used as an assessment tool for laparoscopic skills. However, the current training methods still require the presence of an expert surgeon to assess the surgical dexterity of the trainee. This process is time-consuming and may lead to subjective assessment. This research aims to extend the application of image processing and analysis methods to detect and track the tips of the laparoscopic instruments and to localize the circle center to calculate the distance between the scissors' tips and the circle's center in each processed frame. The data obtained will feed the fuzzy system to assess the trainer’s performance with a processing speed of 4 frames per second. The proposed system can provide a final text report that lists an error counter value and the fuzzy assessment at each time slot of 0.29 s on average. Additionally, a BMP image that summarizes the tips of the scissors within the predefined circles during the test is created. Finally, a Canny edge detector is applied to detect whether any circle line was cut during the test. This work enables a summative assessment of the precision-cutting task without altering the original setup of the FLS box trainer. Additionally, this can expedite the development of surgery skills and assess the trainees’ performance using a single-input-single-output fuzzy logic system. The output of the fuzzy logic assessment is the performance evaluation for the surgeon, and it is quantified in percentages.

Apparatus design of operando hydrogen microscope for visualization of time-dependent distribution of hydrogen

The operando hydrogen microscope is an original apparatus that has been developed to visualize the time-dependent permeation of hydrogen through a sample. This apparatus is developed based on an ultrahigh vacuum scanning electron microscope (UHV SEM). The system consists of a lens system to focus ions produced by electron-stimulated desorption (ESD), an ion detector optimized for ESD-signal detection, and a two-dimensional measurement program synchronized with the position information of the electron beam. The developed detectors and electrostatic lenses enable highly sensitive detection of the ions. In this paper, we show the details of the instrumentation of the operando hydrogen microscope. We have succeeded in recording hydrogen and deuterium flowing from the rear of metals to the surface as a series of time-lapse images, showing the time-dependent changes in the surface distribution of hydrogen and deuterium. Deuterium permeation through the metal sample was dynamically visualized at the surface by the two-dimensional mapping of the desorbed ions induced by scanning electron beam irradiation.

Embrittlement of PFSA Reinforced Membrane Interfaces after Ex-Situ Chemical-Mechanical Aging

Perfluorosulfonic acid (PFSA) membrane degradation has been identified as one of the main factors responsible for the short lifetime of PEMFCs [1,2]. The aging mechanisms of these membranes are complex due to mechanical fatigue combined to chemical aggressions. Mechanical fatigue results from the wetting/drying cycles while the chemical aggressions are induced by radicals formed during fuel cell operation. Although it is commonly accepted that chemical and mechanical stresses can interact to accelerate membrane degradation [3], coupled studies are rarely conducted. Thus, an original experimental set-up to perform ex-situ aging tests combining membrane exposure to cyclic mechanical stresses to a free radical environment under conditions close to those observed during cell operation has been developed [4]. Ex-situ aging was performed on PFSA membranes reinforced (Nafion™ XL) with a cyclic compression oscillating between 0 - 10 MPa (0.1 Hz frequency) and a Fenton solution containing 1 ppm Fe2+ and 3 %vol H2O2. Such stresses revealed a significant morphological alteration with the appearance of “bubbles” close to the surface membrane (Figure 1, left). No chemical structure modification was detected within the three different layers. Nevertheless, SEM-EDX, FTIR and Raman microscopic analyses highlight delamination close to the reinforcement/PFSA interface (Figure 1, rigth). Additional peeling tests argued this failure point in the Nafion™ XL membrane. Figure 1

Aneurismal bone cyst of the medial cuneiform bone: a case report of a new surgical approach and literature review

Introduction An aneurysmal bone cyst (ABC) is a rare, non-neoplastic, destructive, hemorrhagic, and expansile lesion accounting for 1 % of all bone tumors. ABC of the foot is very rare. Patients with foot ABC usually complain of pain and swelling of the affected area. Radiographs and MRI may be helpful in the diagnosis of ABC. No single surgical procedure has gained wide acceptance in the treatment of foot ABC.Purpose To show new effective surgical approach in the treatment of patient with ABC of the medial cuneiform bone.Material and methods We present the case of a 47-year-old woman with a 10-months history of pain and swelling in her right foot. Postoperative histopathological evaluation of resected tissues confirmed the diagnosis of ABC. An en bloc resection (total extraction of the remnant of the medial cuneiform bone) was performed and the defect was replaced with a fibular bone graft from the right leg. Allograft (Bio-Ost®) was placed along the autograft. Tibialis anterior tendon was attached to the fibular bone graft. We performed fixation of the foot and ankle using the Ilizarov original apparatus for prevention of bone graft instability and opportunity for early weight-bearing on the operated foot.Results The postoperative period was uncomplicated with complete healing of the bone defect without recurrence after 12 months of observation. AOFAS score increased significantly from 34 points preoperatively to 92 at 1-year follow-up.Discussion The optimal treatment of this lesion is still under discussion. Different treatment modalities have been described in the literature: wide resection, curettage with or without adjuvants, arterial embolization, intralesional sclerotherapy. Biological reconstruction using bone graft seems to be the best option, but fractures and nonunion are common complications of bone grafting.Conclusion The combination of Ilizarov external fixation and bone grafting provided favorable conditions for the healing of foot bone defect due to ABC without complications, allowed mobility and early weight-bearing of the patient. Recurrence was not detected radiologically. Harvesting of the fibular bone graft did not affect the position of the foot and its movements. Our surgical approach should be considered as a treatment option in similar cases.

The Study of the Electrical Properties of Anisotropic Semiconductors in the Laboratory Workshop of the University Course in Physics

The purpose of the article is to develop a theoretically and experimentally substantiated specific laboratory work for studying the anisotropy of the electrical properties of semiconductors within the framework of the curricula of higher educational institutions, for such areas of training as “Physics”, “Technical Physics”, “Radiophysics” and “Electronics and Nanoelectronics”. The relevance of the problem is due to the desire of domestic electronics for technological sovereignty and high requirements for the training of qualified personnel for the production of structures of solid-state functional electronics. Based on the solution of the boundary electrodynamic problem, an expression is obtained for the electric potential in the region of a thin rectangular semiconductor sample with a tensor character of conductivity. The results of this work is the development of an original laboratory setup for the demonstration and practical study of the anisotropy of the electrical properties of semiconductor crystals. The proposed technique makes it possible to determine the main electrokinetic parameters of an anisotropic semiconductor – specific conductivity, concentration and Hall mobility of the main charge carriers. A schematic diagram of the installation and formulas for calculating the errors of the measured quantities are proposed. The results obtained may also be of scientific interest in the study of anisotropic semiconductor materials in laboratory conditions.

Multi-frequency self-injection locking of a FSR-tunable multimode laser diode.

This study presents the controllable multi-frequency self-injection locking regimes realization with an original experimental setup composed of a reflective semiconductor optical amplifier, an external feedback mirror, and a high-Q chip-scale Si3N4 ring microresonator. Our findings demonstrate the conditions of multiple modes' simultaneous locking being analogous to Vernier effect. We varied the free spectral range of the external-cavity laser by its length tuning, enabling the robust generations from 1 to 4 self-injection locked narrow lines on demand, that is important for optical telecommunications, and photonic-based microwave and THz sources.

Optimal design of stand-alone photovoltaic system based on battery storage system: A case study of Borj Cedria in Tunisia

This work deals with the optimal design of a stand-alone photovoltaic system (SAPS) based on the battery storage system and assesses its technical performance by using PVsyst simulation. In fact, this study is carried out to determine the optimal orientation and tilt angle of a solar panel for collecting maximum solar radiation. Borj Cedria is taken as a case study site to perform the optimum tilt angle through PVsyst. PV-GIS is utilized to estimate global solar irradiance. The proposed system can produce 1314 kWh of energy for the load, which is considered technically suitable for this area thanks to a performance ratio of 58.3% and high specific efficiency generation, besides the solar fraction of about 92.5%. From an economic point of view, the SAPS can save more than 44,000 Dt per year by purchasing energy from the grid system, while considering the aspect of sustainability, 66.24 kg of CO2 annually can be avoided by utilizing the sun’s energy. Furthermore, efficient solar panel use requires its characteristics to be identified under various conditions. An original experimental setup is carried out in the LPV Lab to identify PV characteristics. Experimental and simulation results performed under PSIM software are in good agreement, which shows the experimental setup’s effectiveness.

Intermediate LET-like effect in distal part of proton Bragg peak revealed by track-ends imaging during super-Fricke radiolysis

Upstream of the efficiency of proton or carbon ion beams in cancer therapy, and to optimize hadrontherapy results, we analysed the chemistry of Fricke solutions in track-end of 64-MeV protons and 1.14-GeV carbon ions. An original optical setup is designed to determine the primary track-segment yields along the last millimetres of the ion track with a sub-millimetre resolution. The Fe3+-yield falls in the Bragg peak to (4.9 ± 0.4) × 10–7 mol/J and 1.9 × 10–7 mol/J, under protons and carbon ions respectively. Beyond the Bragg peak, a yield recovery is observed over 1 mm for proton beams. It is attributed to the intermediate-LET of protons in this region where their energy decreases and energy distribution becomes broader, in relation with the longitudinal straggling of the beam. Consequently to this LET decrease in the distal part of the Bragg peak, Fe3+-yield increases. For the first time, this signature is highlighted at the chemical level under proton irradiation. Nevertheless, this phenomenon is not identified for carbon ion beams since their straggling is lower. It would need a greater spatial resolution to be observed.

Thermo-migration of moisture in Norway spruce assessed by in-situ micro-tomography

Wood used as a building material is exposed to non-isothermal and unsteady state conditions involving coupled heat and mass transfer within the porous media. These exchanges contribute to the regulation of relative humidity in a passive way and influence the energy performance of buildings. In order to characterize the importance of the hygrothermal behaviour of softwoods in this context, an experimental setup was developed to access to moisture fluxes and/or moisture content profiles in the presence of a known temperature difference imposed on both sides of the wood sample. This original setup was conceived to maintain the temperature gap during micro-tomography acquisition. Image processing allows the moisture content profiles to be obtained over time after changes of the thermal gradient. The simulation using a computational model of coupled heat and mass transfer confirmed that the gradient of vapor density is a relevant unique, “synthetic”, driving force to account for moisture migration in non-isothermal conditions.

In process temperature and tool wear for the machining of aeronautic aluminum under different lubrication conditions

The use of aluminum-lithium alloys in aeronautics is an efficient solution for lightweight structures, but its machinability can cause increased tool wear. The cutting temperature is one of the most important parameters controlling the tool wear and the quality of machined surfaces. Therefore, its measurement is of great interest to analyze the heat generation during the cut and then being able to limit it in the cutting edge. This article presents an original experimental study of the cutting temperature of two aluminum alloys (7000 series and Li-containing 2000 series), for dry, MQL: Minimum Quantity of Lubrication and wet machining conditions. The interactions between tool wear and cutting temperature are also investigated. To be able to observe tool wear, the milling of very large volumes of aluminum alloys has been necessary since the tool lifetime is several hours when machining this kind of material. To measure temperature as close as possible the cutting zone, an original set-up with machinable thermocouples was used, enabling measurements on a large frequency bandwidth. Complementary investigations by Second Ion Mass Spectroscopy revealed a diffusion of lithium in the cutting insert, which can reduce its lifetime (divided by 8, with the Li-containing 2000 series compared to the 7000 series).

The role of plasma β in global coronal models: Bringing balance back to the force

Context. COolfluid COrona uNstrUcTured (COCONUT) is a global coronal magnetohydrodynamic (MHD) model that was recently developed and will soon be integrated into the ESA Virtual Space Weather Modelling Centre (VSWMC). In order to achieve robustness and fast convergence to a steady state for numerical simulations with COCONUT, several assumptions and simplifications were made during its development, such as prescribing filtered photospheric magnetic maps to represent the magnetic field conditions in the lower corona. This filtering leads to smoothing and lower magnetic field values at the inner boundary (i.e. the solar surface), resulting in an unrealistically high plasma β (greater than 1 in a large portion of the domain). Aims. We aim to examine the effects of prescribing such filtered magnetograms in global coronal simulations and formulate a method for achieving more realistic plasma β values and improving the resolution of electromagnetic features without losing computational performance. Methods. We made use of the newly developed COCONUT solver to demonstrate the effects of the highly pre-processed magnetic maps set at the inner boundary and the resulting high plasma β on the features in the computational domain. Then, in our new approach, we shifted the inner boundary to 2 R⊙ from the original 1.01 R⊙ and preserved the prescribed highly filtered magnetic map. With the shifted boundary, the boundary density and pressure were also naturally adjusted to better represent the considered physical location. This effectively reduces the prescribed plasma β and leads to a more realistic setup. The method was applied on a magnetic dipole, a minimum (2008) and a maximum (2012) solar activity case, to demonstrate its effects. Results. The results obtained with the proposed approach show significant improvements in the resolved density and radial velocity profiles, and far more realistic values of the plasma β at the boundary and inside the computational domain. This is also demonstrated via synthetic white light imaging (WLI) and with the validation against tomography data. The computational performance comparison shows similar convergence to a limit residual on the same grid when compared to the original setup. Considering that the grid can be further coarsened with this new setup, as its capacity to resolve features or structures is superior, the operational performance can be additionally increased if needed. Conclusions. The newly developed method is thus deemed as a good potential replacement of the original setup for operational purposes, providing higher physical detail of the resolved profiles while preserving a good convergence and robustness of the solver.

Interaction mechanisms between Atomic Oxygen and materials: investigation on reflected beam

Atomic Oxygen (AO) is the main component of the residual atmosphere present at low earth orbit. Multiple reflections can locally enhance or lower erosion rate in case of complex geometry. The need for precise estimate of hyperthermal AO flux is thus crucial at critical target embedded into realistic assembly. Industrial modeling tools (example Atomox module in ESABASE2 and SYSTEMA toolboxes) may account for multiple reflections with simplistic approach (ray-tracing) and a set of semi-empirical parameters. In this context, an original geometrical setup was designed in order to expose target surfaces with normal and tilted incidences and after one reflection on a set of materials of interest (black conductive thermal coatings, coverglass, surface treatment…). Candidate materials have been selected in view to compare numerical results and experimental ones. Results of two test campaigns highlight the effect of incidence angle on erosion rate (higher erosion with tilted beam) and provide an estimate of residual fluence after one reflection (in the 4-10 % range depending on material type). First computations with engineering codes have been successfully conducted, the erosion patterns being rather well described with some basic hypotheses on material parameters (absorption, specular/diffuse reflection) and taken into account the reflection on adjacent metallic surfaces.

Daytime convective development over land: The role of surface forcing

AbstractWater availability at the Earth surface determines the portioning of the surface heat flux into its sensible and latent components, that is, the surface heat flux Bowen ratio. The two components affect differently the surface buoyancy flux and thus the development and growth of the convective boundary layer. As a result, the Bowen ratio has a strong impact on the daytime development of dry and moist convection over land. We use two canonical modeling test cases, one for the shallow convection and one for the shallow‐to‐deep convection transition, to document the impact of the surface Bowen ratio on daytime convection development. A simple approach is used where results from simulations featuring the original setup are contrasted with simulations where the surface‐sensible heat flux takes on values of the latent heat flux and vice versa. Such a change illustrates the key impact of the surface water availability without changing the total surface heat flux. Because of the larger surface buoyancy flux, simulations with the reversed surface heat fluxes feature faster deepening of the convective boundary layer and wider clouds once moist convection develops. Mean cloud‐base width of cumulus clouds increases with the boundary‐layer depth. For shallow‐to‐deep convection transition, comparison of simulations with the observed large‐scale flow that feature substantial lower‐tropospheric shear with simulations with no mean horizontal flow suggests that the organization of convective circulations within the boundary layer strongly affects initial size and organization of shallow convection, as well as the subsequent width increase once convection deepens and eventually transitions to deep precipitating convection. A simple explanation is provided of why a deeper well‐mixed convective subcloud layer results in wider clouds. The key is the larger width of boundary‐layer coherent updraft structures when the mixed layer is deeper.

Экспериментально-аналитические исследования пожарной опасности материалов, применяемых в оборудовании с обогащенными кислородом средамипри повышенных давлениях, и пути снижения их горючести

Introductio n. Sealed equipment (hereinafter referred to as hermetic chambers) is used in various branches of economy. Atmospheres enriched with oxygen (in some cases under variable pressure conditions) are used. It was shown that the main reason of the fires in the pressurized chambers was the unregulated use of the electrical equipment, as well as combustible substances and materials on the basis of organic compounds included in the materials used in the pressurized chambers. Objective. To find ways to decrease combustibility of materials used in pressurized chambers and to study fire risk parameters of pressurized chambers with high oxygen content and increased pressure. Obje ctives. To determine the boundary conditions of applying materials with increased values of temperature, oxygen content and pressure and analyze the results of experimental studies of combustibility of materials used in sealed chambers. Research met hods. Investigation of the characteristics of the combustion process of non-metallic materials under increased pressure was carried out on an original setup represented by a stainless steel vessel with a height of 750 mm and an inner diameter of 155 mm. A spiral of nichrome wire was used to ignite the sample. The pressure was fixed with a manometer. Results and th eir discussion. As a result of experimental research of fire hazard of construction and construction materials in oxygen-enriched media and under increased pressure the ways of increasing the oxygen concentration limit (OCL) and reduction of combustibility of materials were determined: application of heat-removing surface, incombustible shell; putting inhibitors in their composition and structure; surface treatment with different fire protective compositions and impregnations. When studying the parameters of fire hazard (flame propagation velocity, heat of combustion, autoignition temperature) of materials under the conditions of changes in the composition of nitrogen-oxygen atmosphere and pressure, it was found that the OCL for all materials decreases at higher pressures. Conc lusions. It is found that the limiting oxygen concentration depends on the geometrical dimensions of the sample, as well as on the speed of the gas flow. At higher pressures the OCL for all the materials decreases. The presence of a heat-removing surface also leads to higher OCL, which increases with increasing substrate thickness and decreasing thickness of the material on it. For materials not containing substances that inhibit the combustion reaction, a decrease in the LOC value with an increase in the number of hydrogen atoms in the polymer macromolecule is characteristic.

A gridded multi-site precipitation generator for complex terrain: an evaluation in the Austrian Alps

Abstract. For climate change impact assessment, many applications require very high-resolution, spatiotemporally consistent precipitation data on current or future climate. In this regard, stochastic weather generators are designed as a statistical downscaling tool that can provide such data. Here, we adopt the precipitation generator framework of Kleiber et al. (2012), which is based on latent and transformed Gaussian processes, and propose an extension of that framework for a mountainous region with complex topography by allowing elevation dependence in the model. The model is used to generate two-dimensional fields of precipitation with a 1 km spatial resolution and a daily temporal resolution in a small region with highly complex terrain in the Austrian Alps. This study aims to evaluate the model with respect to its ability to simulate realistic precipitation fields over the region using historical observations from a network of 29 meteorological stations as input. The model's added value over the original setup and its limitations are also discussed. The results show that the model generates realistic fields of precipitation with good spatial and temporal variability. The model is able to generate some of the difficult areal statistics useful for impact assessment, such as the areal dry and wet spells of different lengths and the areal monthly mean of precipitation, with great accuracy. The model also captures the inter-seasonal and intra-seasonal variability very well, while the inter-annual variability is well captured in summer but largely underestimated in autumn and winter. The proposed model adds substantial value over the original modeling framework, specifically with respect to the precipitation amount. The model is unable to reproduce the realistic spatiotemporal characteristics of precipitation in autumn. We conclude that, with further development, the model is a promising tool for downscaling precipitation in complex terrain for a wide range of applications in impact assessment studies.

Experimental evaluation of the use of embedded fiber Bragg gratings to measure steady and unsteady flow-induced marine propeller blade deformation

This paper presents an experimental study that investigates the deformation of a composite propeller blade subjected to a uniform inflow. An array of fiber Bragg grating sensors were embedded inside the blade, allowing for real-time monitoring of strain. Measurements were carried out in the towing tank at Centrale Nantes, France. An original experimental setup was developed to support and fully submerge the blade in the hydrodynamic facility, which reduced the effect of the free surface during testing. The blade, with a root chord of 0.3 m and a span of 0.5 m, was instrumented with embedded fiber Bragg grating (FBG) sensors on both the pressure and suction sides to measure the deformation field. The FBG measurements were dynamically synchronized with a six degree-of-freedom hydrodynamic balance to measure the loads and moments on the blade. Visualizations of the boundary layer regime were observed to determine the flow detachment regions at the surface. The carriage velocities utilized were between 1 and 4m/s and the angle of attack of the blade, based on the zero-lift angle of attack, ranged between 0 to 12∘. After determining the natural frequencies and modes of the blade using laser doppler vibrometry, the forces and deformations were investigated under hydrodynamic flow for both averaged and unsteady data. For averaged results, a good correlation is observed between the lift force and deformations, which demonstrates the accuracy of the measurement system. The fluid–structure interaction dynamic is analyzed using the frequency spectra of drag, lift, pitching moment, and deformations. The interaction between Strouhal frequencies of vortex shedding resulting from flow detachments at the blade surface is identified with the flow visualization, and the modal response of the blade is demonstrated.

Customization of an atomic force microscope for multidimensional measurements under environmental conditions.

Atomic force microscopy (AFM) is an analytical surface characterization tool that reveals the surface topography at a nanometer length scale while probing local chemical, mechanical, and even electronic sample properties. Both contact (performed with a constant deflection of the cantilever probe) and dynamic operation modes (enabled by demodulation of the oscillation signal under tip-sample interaction) can be employed to conduct AFM-based measurements. Although surface topography is accessible regardless of the operation mode, the resolution and the availability of the quantified surface properties depend on the mode of operation. However, advanced imaging techniques, such as frequency modulation, to achieve high resolution, quantitative surface properties are not implemented in many commercial systems. Here, we show the step-by-step customization of an atomic force microscope. The original system was capable of surface topography and basic force spectroscopy measurements while employing environmental control, such as temperature variation of the sample/tip, etc. We upgraded this original setup with additional hardware (e.g., a lock-in amplifier with phase-locked loop capacity, a high-voltage amplifier, and a new controller) and software integration while utilizing its environmental control features. We show the capabilities of the customized system with frequency modulation-based topography experiments and automated voltage and/or distance spectroscopy, time-resolved AFM, and two-dimensional force spectroscopy measurements under ambient conditions. We also illustrate the enhanced stability of the setup with active topography and frequency drift corrections. We believe that our methodology can be useful for the customization and automation of other scanning probe systems.

New calibration setup for quantitative DCE-US imaging protocol: Toward standardization.

The DCE-US (Dynamic Contrast-Enhanced Ultrasonography) imaging protocol predicts the vascular modifications compared with Response Evaluation Criteria in Solid Tumors (RECIST) based mainly on morphological changes. A quantitative biomarker has been validated through the DCE-US multi-centric study for early monitoring of the efficiency of anti-angiogenic cancer treatments. In this context, the question of transposing the use of this biomarker to other types of ultrasound scanners, probes and settings has arisen to maintain the follow-up of patients under anti-angiogenic treatments. As a consequence, radiologists encounter standardization issues between the different generations of ultrasound scanners to perform quantitative imaging protocols. The aim of this study was to develop a new calibration setup to transpose the DCE-US imaging protocol to the new generation of ultrasound scanners using both abdominal and linear probes. This calibration method has been designed to be easily reproducible and optimized, reducing the time required and cost incurred. It is based on an original set-up that includes using a concentration splitter to measure the variation of the harmonic signal intensity, obtained from the Area Under the time-intensity Curve (AUC) as a function of various contrast-agent concentrations. The splitter provided four different concentrations simultaneously ranging from 12.5% to 100% of the initial concentration of the SonoVue contrast agent (Bracco Imaging S.p.A., Milan, Italy), therefore, measuring four AUCs in a single injection. The plot of the AUC as a function of the four contrast agent concentrations represents the intensity variation of the harmonic signal: the slope being the calibration parameter. The standardization through this method implied that both generations of ultrasound scanners had to have the same slopes to be considered as calibrated. This method was tested on two ultrasound scanners from the same manufacturer (Aplio500, Aplioi900, Canon Medical Systems, Tokyo, Japan). The Aplio500 used the settings defined by the initial multicenter DCE-US study. The Mechanical Index (MI) and the Color Gain (CG) of the Aplioi900 have been adjusted to match those of the Aplio500. The reliability of the new setup was evaluated in terms of measurement repeatability, and reproducibility with the agreement between the measurements obtained once the two ultrasound scanners were calibrated. The new setup provided excellent repeatability measurements with a value of 96.8%. Once the two ultrasound scanners have been calibrated for both types of probes, the reproducibility was excellent with the agreement between their respective quantitative measurement was at the lowest 95.4% and at the best 98.8%. The settings of the Aplioi900 (Canon Medical Systems) were adjusted to match those of the Aplio500 (Canon Medical Systems) and these validated settings were for the abdominal probe: MI=0.13 and CG=34dB; and for the linear probe: MI=0.10 and CG=38dB. This new calibration setup provided reliable measurements and enabled the rapid transfer and the use of the DCE-US imaging protocol on new ultrasound scanners, thus permitting a continuation of the therapeutic evaluation of patients through quantitative imaging.

Composites Based on Cotton Microfibers Impregnated with Magnetic Liquid for Magneto-Tactile Sensors.

In this paper, we report the preparation of two new composite materials based on cotton fibers and magnetic liquid consisting of magnetite nanoparticles and light mineral oil. Using the composites and two simple textolite plates plated with copper foil assembled with self-adhesive tape, electrical devices are manufactured. By using an original experimental setup, we measured the electrical capacitance and the loss tangent in a medium-frequency electric field superimposed on a magnetic field. We found that in the presence of the magnetic field, the electrical capacity and the electrical resistance of the device change significantly with the increase of the magnetic field, then, the electrical device is suitable to be used as a magnetic sensor. Furthermore, the electrical response functions of the sensor, for fixed values of the magnetic flux density, change linearly with the increase in the value of the mechanical deformation stress, which gives it a tactile function. When applying mechanical stresses of fixed values, by increasing the value of the magnetic flux density, the capacitive and resistive functions of the electrical device change significantly. So, by using the external magnetic field, the sensitivity of the magneto-tactile sensor increases, therefore the electrical response of this device can be amplified in the case of low values of mechanical tension. This makes the new composites promising candidates for the fabrication of magneto-tactile sensors.