Mohamed Bouri

The WalkTrainer—A New Generation of Walking Reeducation Device Combining Orthoses and Muscle Stimulation

This paper presents a novel reeducation device for paraplegics that combines hybrid orthoses and closed-loop electrical muscle stimulation. Based on the so called cyberthosis concept, the WalkTrainer enables an active muscular participation of the subject in the walking reeducation process by the mean of closed-loop muscle stimulation. The WalkTrainer is also equipped with a leg and pelvic orthosis, an active bodyweight support, and motorized wheels to allow true over ground deambulation. This paper will focus on the development of the WalkTrainer, the presentation of the control strategies, and also give some preliminary results of the first clinical trials.

Magnetic (nano)materials as an useful tool for sample preparation in analytical methods. A review

This review, with more than 170 references, presents a general overview of the use of magnetic nanoparticles (MNPs) to perform sample preparation. In this way, the main types of MNPs used for this purpose, such as magnetic molecularly imprinted polymer (MMIP), noble metal coated MNPs, carbon nanotubes (CNTs), quantum dots (QDs), silica, and surfactant are described in terms of their composition, properties, and synergetic potential. Finally, some examples of their analytical applications are reported, as well as pointing out possible future applications of MNPs in the analytical field.

Selective extraction and determination of catecholamines in urine samples by using a dopamine magnetic molecularly imprinted polymer and capillary electrophoresis

A rapid and selective method for the extraction and determination of catecholamines (CLs) from urine samples has been successfully developed using a magnetic molecularly imprinted polymer (MMIP) as a sorbent material. The MMIP has been prepared using dopamine hydrochloride (DA) as template molecule, methacrylic acid (MAA) as functional monomer, ethylene glycol dimethacrylate (EDMA) as cross-linking agent and Fe(3)O(4) magnetite as magnetic component. The extraction was carried out by stirring urine samples with the magnetic polymer. When the extraction was completed, the MMIP, together with the captured analytes, was easily separated from the sample matrix by an adscititious magnet. The analytes desorbed from the MMIP were determined by capillary electrophoresis (CE). It was shown that the MMIP had high affinity and selectivity toward DA and other structurally related CLs such as 3-methoxytyramine hydrochloride (MT), DL-normetanephrine hydrochloride (NME), DL-norephinephrine hydrochloride (NE) and (±) epinephrine (E). Different parameters affecting the extraction efficiency were evaluated in order to achieve the optimal pre-concentration of the analytes and to reduce non-specific interactions. Under the optimal conditions, the CL limits of detection were at the 0.04-0.06 μM range. The relative standard deviations of migration time and response ranged from 0.7% to 1.4% and from 2.9% to 5.5%, respectively. The proposed method was successfully applied to determine CLs, including MT, NME, DA, NE and E in human urine samples.

The WalkTrainer: A Robotic System for Walking Rehabilitation

Robots are excellent tools for providing motion. Their motion is precise, stiff and as repeatable as we need. This led the Swiss Foundation for Cyberthosis (SFC) to exploit robotics jointly with the muscle electrostimulation as intelligent rehabilitation devices. This paper will present one of this devices developed by the Laboratoire des Systemes Robotiques (LSRO) at the EPFL (Ecole Polytechnique Federate de Lausanne). This device called The WalkTrainerTM is a robotic rehabilitation system composed by a deambulator, a pelvis orthosis, a body weight support, two leg orthoses and a real time controlled electrostimulator. The WalkTrainerTM is a verticalized system allowing walking rehabilitation process. It can be used for paraplegic and hemiplegic persons. Clinical trials will be performed at the beginning of 2007. In the first part of this paper the context of the development of such devices is presented by introducing a stationary rehabilitation system: the MotionMakerTM. The very encouraging clinical results obtained with this rehabilitation system are briefly presented in this paper and prove the rightness of the concept (Robotic system + Electrostimulation ⇒ Rehabilitation process). In the second part, the WalkTrainerTM is presented with its components (robotic components and the controller). Finally, we will introduce the use of the WalkTrainerTM, its flexibility and diversity of use either for diagnosis, test or measurement and walking rehabilitation.

Ionic liquids supported on magnetic nanoparticles as a sorbent preconcentration material for sulfonylurea herbicides prior to their determination by capillary liquid chromatography.

AbstractA magnetic material based on N-methylimidazolium ionic liquid and Fe3O4 magnetic nanoparticles incorporated in a silica matrix has been used to extract and preconcentrate sulfonylurea herbicides, such as thifensulfuron methyl (TSM), metsulfuron methyl (MSM), triasulfuron (TS), tribenuron methyl (TBM) and primisulfuron methyl (PSM) from polluted water samples, prior to their analysis by capillary liquid chromatography with a diode array detector (DAD). Under the optimum conditions, this method allows the determination of TSM, MSM, TS, TBM and PSM in a linear range between 5 and 100xa0ngxa0mL−1, with relative standard deviation values lower than 5.3xa0% (nu2009=u200910), in all cases. Detection limits ranging between 1.13 and 2.95xa0ngxa0mL−1 were achieved. The usefulness of the proposed method was demonstrated by the analysis of river water samples, obtaining recoveries higher than 91xa0%.n Figureu2009

A novel approach to size separation of gold nanoparticles by capillary electrophoresis–evaporative light scattering detection

A simple and rapid methodology to separate and characterize gold nanoparticles (AuNPs) in aqueous medium by capillary electrophoresis–evaporative light scattering detection (CE–ELSD) is presented. First, a controlled synthesis procedure to obtain water-soluble AuNPs, by varying the trisodium citrate concentration was described. These free AuNPs were separated by capillary zone electrophoresis (CZE) based on the differences in the charge-to-mass ratio of the AuNPs–citrate in a mixed buffer of ammonium acetate (20 mM), containing tris(hydroxymethyl)-aminomethane (Tris, 20 mM) and 3-(cyclohexylamino)-1-propanesulfonic acid (CAPS; 10 mM) at pH 8.5. Under optimal working conditions, three small different-sized AuNPs were successfully separated whose average sizes were 3.5, 6.5 and 10.5 nm. The average diameter was lower than 1.2 nm for all of them (calculated by high-resolution transmission electron microscopy, TEM). Thus, this CE-based method was able to separate AuNPs that differ by only 3 nm in diameter. It can be a valuable methodology for the rapid and cost-effective characterization of other nanomaterials in the future in aqueous solutions.

Argan hulls extract: green inhibitor of mild steel corrosion in 1 M HCl solution

Argan hulls extract (AHE) was tested as corrosion inhibitor for mild steel in 1xa0M HCl. Weight loss measurements, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) revealed that inhibiting action increased with increasing concentration of the inhibitor. The highest efficiency 97.3% was obtained at 5xa0g/L AHE. There was good agreement between gravimetric and electrochemical methods (potentiodynamic polarization and EIS). Results obtained from EIS measurements were analyzed to model the corrosion-inhibition process by use of the appropriate equivalent circuit model; a constant phase element was used. Polarization measurements show also that AHE acts as good mixed inhibitor. AHE is adsorbed on the steel surface in accordance with a Langmuir isotherm adsorption model.

Capillary electrophoresis coupled to evaporative light scattering detection for direct determination of underivatized amino acids: Application to tea samples using carboxyled single‐walled carbon nanotubes for sample preparation

An improved and efficient method for the determination of underivatized amino acids based on the use of CE coupled to evaporative light scattering detector (ELSD), involving carbon nanotubes, was successfully developed. Carboxyled single‐walled carbon nanotubes were used for the first time to perform the clean‐up of the analyzed samples, which were afterwards analyzed by CE‐ELSD. White tea samples were used to demonstrate the usefulness of the CE‐ELSD coupled methodology. A suitable interface, based on a triple tube design sprayer, was developed and successfully used for coupling both instruments. Parameters affecting the separation and determination, including the elimination of interferences, were studied and properly optimized. Under the optimized conditions good resolution was achieved for the separation of seven amino acids. The precision of the method, expressed as RSD, was found within the 3.5–5.3% range. The LOD obtained for the proposed method were in the 1.2–2.1 pg range and the LOQ, were in the 2.0–11.5 pg range, with injection pressure of 5 KPa for 20 s (15.3 nL). This method is simple, rapid, and selective compared with other conventional techniques.

Design and Adaptation of an Interface for Commercial Capillary Electrophoresis—Evaporative Light Scattering Detection Coupling

In this technical note, an interface for coupling commercially available capillary electrophoresis (CE) equipment to an evaporative light scattering detector (ELSD) is described. The nebulization process was identified as the most critical parameter for performing the reliable coupling between both pieces of equipment. Therefore, appropriate modifications in the nebulization chamber and in the conventional nebulizer were brought to make ELSD fully compatible with CE. The impact of the customized interface on CE separation and detection was evaluated in terms of resolution and sensitivity. ELSD can be considered as an attractive alternative to other CE detection systems (e.g., UV-vis, fluorescence, electrochemical detection, or even MS detection), particularly those in which derivatization is needed. This advantage is due to the versatility and the quasi-universality of ELSD. Thus, sensitive and fast separations of several compounds were performed using this CE-ELSD customized arrangement, which opens up an interesting analytical potential for the determination of compounds not presenting sensitive UV-vis chormophore, fluorophore, or electroactive groups. Carbohydrates were selected in this work to demonstrate the applicability of CE-ELSD coupling.

A Novel Verticalized Reeducation Device for Spinal Cord Injuries: the WalkTrainer, from Design to Clinical Trials

Robotic assistive devices have been developed and are now being introduced in clinical environments. Such robots can advantageously provide long raining, with quantifiable mobilization (force and position). But in the event of a complete lesion the patient’s muscles remain completely passive. To overcome that issue electrical muscle stimulation can be employed. The complex nature of the muscles associated to the dynamics of walking, require subtle stimulation schemes which rely on position and force information provided by the robot. The combination of muscle stimulation (preferably in a closed loop manner to avoid rapid exhaustion and guarantee better control) and robotic mobilization optimizes the afferent feedback provided to the subject and allows an effective muscle training. The WalkTrainer that is one of these reeducation devices, will be extensively presented in this chapter.