Miguel García

Superhydrophobic Alkanethiol-Coated Microsubmarines for Effective Removal of Oil

We demonstrate the use of artificial nanomachines for effective interaction, capture, transport, and removal of oil droplets. The simple nanomachine-enabled oil collection method is based on modifying microtube engines with a superhydrophobic layer able to adsorb oil by means of its strong adhesion to a long chain of self-assembled monolayers (SAMs) of alkanethiols created on the rough gold outer surface of the device. The resultant SAM-coated Au/Ni/PEDOT/Pt microsubmarine displays continuous interaction with large oil droplets and is capable of loading and transporting multiple small oil droplets. The influence of the alkanethiol chain length, polarity, and head functional group and hence of the surface hydrophobicity upon the oil-nanomotor interaction and the propulsion is examined. No such oil-motor interactions were observed in control experiments involving both unmodified microengines and microengines coated with SAM layers containing a polar terminal group. These results demonstrate that such SAM-Au/Ni/PEDOT/Pt micromachines can be useful for a facile, rapid, and efficient collection of oils in water samples, which can be potentially exploited for other water-oil separation systems. The integration of oil-sorption properties into self-propelled microengines holds great promise for the remediation of oil-contaminated water samples and for the isolation of other hydrophobic targets, such as drugs.

Microchips for CE: Breakthroughs in real-world food analysis

The well‐known complexity of food matrices is approached using CE microchips with different strategies to improve the selectivity and sensitivity of the analysis by avoiding and/or making the sample preparation as simple as possible: (i) enhancing the peak capacity in order to perform direct injection, (ii) using the microchip platform to measure one target analyte/group of analytes with or without separating other related interferences, (iii) integrating sample preparation steps on the microchip platform, and (iv) integrating new analytical tools from nanotechnology in the detection stage. New analyte separations of food significance involving DNA probes, biogenic amines, vanilla flavors, and dyes have been reported as successfully breaking new barriers in areas of high impact in the market, such as transgenic food analysis, as well as the detection of frauds and toxins. Simple microchip layouts are still the most common designs used, though sophisticated new ones are emerging. In contrast to other application areas, electrochemical detection continues to be the most common detection route, followed by LIF, though non‐conventional detection routes are also emerging, such as chemiluminescence or UV. In terms of analytical performance, the integration of calibration and quality control on a microchip platform, and remarkable accuracy and precision are being obtained using creative analytical methodologies that enhance the analytical potency of microfluidic chips for their future commercialization. This review critically states the most important advances derived from work done in the field over the past 2–3 years.

Liver Transplantation in HIV-infected recipients

Liver transplantation is being evaluated as a therapeutic option for human immunodeficiency virus (HIV)‐infected patients with end‐stage liver disease, but experience is still scarce. We describe the outcome of 4 HIV‐infected patients who underwent liver transplantation in our hospital between July 2002 and April 2003. HIV‐infected liver transplant recipients meet the same standard criteria for transplantation as do HIV‐negative candidates. In addition, HIV infected persons are required to have a CD4 T‐cell count greater than 100/mL (CD4 T‐cells are targets for HIV infection). Immunosuppressive regimens, perioperative surgical prophylaxis, and prophylaxis for opportunistic infections are standard in the Liver Transplantation Unit in our hospital. Four patients, including 3 former intravenous drug users, received a liver transplant (2 from deceased donors and 2 from living donors), with a median follow‐up of 510 days. Three patients (75%) are alive, with 1 death occurring 17 months posttransplantation in a patient who developed fibrosing cholestatic hepatitis. Rejection occurred in 1 patient, and was managed with no complications. Hepatitis C virus (HCV) recurrence occurred in 3 patients. HIV‐infection has remained under control with antiretroviral treatment. A combination of 3 nucleoside analogs was used in 3 patients, with no need for drug adjustments. No opportunistic infections or other significant infectious complications developed. In conclusion, orthotopic liver transplantation seems a safe therapeutic option in the short term for HIV‐infected persons with end stage liver disease, including patients with a history of drug abuse. If indicated, an antiretroviral regimen consisting of 3 nucleosides could be used to avoid interactions with immunosuppressive drugs. (Liver Transpl 2005;11:76–81.)

Copper nanowires immobilized on the boards of microfluidic chips for the rapid and simultaneous diagnosis of galactosemia diseases in newborn urine samples.

Galactosemia is a rare disease that is diagnosed through the identification of different metabolite profiles. Therefore, the specific detection of galactose 1-phosphate (Gal 1-P), galactose (Gal), and uridyl diphosphate galactose (UDP-Gal) confirms type I, II, and III galactosemia diseases. Because of the low prevalence of galactosemia, sample availability is very scarce and screening methods to diagnose the illness are not commonly employed around the world. This work describes the coupling of microfluidic chips (MCs) to copper nanowires (CuNWs) as electrochemical detectors for the fast diagnosis of galactosemia in precious newborn urine samples. Conceptually speaking, we hypothesize that the inherent selectivity and sensitivity of CuNWs, toward galactosemia metabolites detection in connection with MC selectivity could allow the fast and simultaneous detection of the three galactosemia biomarkers, which implies the fast diagnosis of any galactosemia type in just one single analysis. Electrosynthesized CuNWs show a well-defined shape, with an average length of 6 μm and a width of 300 nm. The modified electrodes exhibited an enhanced electroactive surface area twice as high as the nonmodified ones. Very good intraelectrode repeatability with relative standard deviations (RSDs) of <8% (n = 10) and interelectrode reproducibility with RSDs of <12% (n = 5) were obtained, indicating an excellent stability of the nanoscaled electrochemical detector. Under optimum chemical (3 mM NaOH, pH 11.5), electrokinetic (separation voltage +750 V, injection +1500 V for 5 s) and electrochemical (E = +0.70 V in 3 mM NaOH, pH 11.5) conditions, galactosemia diseases were unequivocally identified, differentiating between type I, II, and III, using selected precious ill diagnosed newborn urine samples. Detection proceeded within less than 350 s, required negligible urine sample consumption, and displayed impressive signal-to-noise characteristics (ranging from 14 to 80) and micromolar limits of detection (LODs) much lower than the cutoff levels (Gal 1-P > 0.4 mM and Gal > 1.4 mM). Excellent reproducible recoveries (93%-107%, RSDs <6%) were also achieved, revealing the reliability of the approach. The significance of the newborn urine samples studied confirms the analytical potency of MC-CuNWs approach, enhancing the maturity of the microchip technology and opening new avenues for future implementation of screening applications in the field.

Microchip electrophoresis–copper nanowires for fast and reliable determination of monossacharides in honey samples

Microchip electrophoresis (ME) with electrochemical detection has been demonstrated to be a powerful tool in food analysis. However, the coupling of ME with electrochemical detection and nanotechnologies is still in its infancy, knowing that nanomaterials can significantly improve the ME analytical performance. This work reports the coupling between ME and copper nanowires (CuNWs) for the selective analysis of monosaccharides in honey samples. Also, in terms of real applicability, the study of analytical reliability of ME is an issue of paramount importance. To this end, a representative group of nine honey samples were analyzed and the results were compared with those previously obtained by HPLC‐refractive index. ME‐CuNWs approach allowed the separation of glucose and fructose in <250 s under optimized separation (20 mM NaOH + 10 mM H3BO3, pH 12; separation voltage + 1000 V) and detection (E = +0.70 V in 20 mM NaOH + 10 mM H3BO3, pH 12) conditions. An excellent stability of EOF during sample analysis was achieved with RSDs for migration times <2% and for amperometric currents <9%. The quantitative contents for individual glucose and fructose obtained using ME‐CuNWs in comparison with those obtained by HPLC‐refractive index were highly in agreement with errors <10% indicating the reliability of the approach. The excellent analytical performance obtained confirms the analytical potency of ME‐CuNWs approach, enhancing the maturity of the microchip technology and opening new avenues for future implementation of applications in the field of food analysis.

Traffic sign detection in static images using Matlab

In this paper a system for off-line traffic sign detection is shown. Matlab-image-processing toolbox is used for this purpose. The vision-based traffic sign detection module developed in this work manages 172/spl times/352 color images in RGB (red, green, blue) format. The first step in the algorithm is to obtain the gradient image and its vertical edge projection. In a second step, a color and shape analysis is performed.

Low level controller for a POMDP based on WiFi observations

This paper shows the results of a low level controller that has been applied to an autonomous robotic system using a WiFi-based Partially Observable Markov Decision Process (POMDP). These observations provide a clue for global robot localization from the first iteration of the POMDP algorithm. Due to the noise channel of WiFi measures, it becomes necessary to make observations at a well known location within the environment. Therefore, a robust local navigator is needed in order to place the robot in an optimal position for making the observation. The system has been tested with two Pioneer 2AT robots in the premises of the Department of Electronics at the University of Alcala.

Vision Based Intelligent System for Autonomous and Assisted Downtown Driving

Autonomous and assisted driving in city urban areas is a challeging topic that needs to be addressed during the following ten to twenty years. In the current work an attempt in this direction is carried out by using vision-based systems not only for autonomous vehicle driving, but in helping the driver recognize vehicles, and traffic signs. Some well consolidated results have been attained on a private test circuit using a commercial Citroen Berlingo as described in this paper.

Ego-motion computing for vehicle velocity estimation

In this paper, we present a method for computing velocity using a single camera onboard a road vehicle, i.e. an automobile. The use of computer vision provides a reliable method to measure vehicle velocity based on egomotion computation. By doing so, cumulative errors inherent to odometry-based systems can be reduced to some extent. Road lane markings are the basic features used by the algorithm. They are detected in the image plane and grouped in couples in order to provide geometrically constrained vectors that make viable the computation of vehicle motion in a sequence of images. The applications of this method can be mainly found in the domains of Robotics and Intelligent Vehicles.

Software Requirements for Ubiquitous Ad Hoc Mobile Networks: An Example of a Bluetooth Application

In contrast with the simple and elegant concept of global computing, also called ubiquitous computing - where daily life objects get now computing capacity and interact among them to provide a wide range of services to users - a major difficulty is arising with the software engineering process to develop applications for these devices. This article discusses the additional parameters that should be taken into account when designing and developing software for ubiquitous devices in ad-hoc networks. In these networks the mobility of the devices could increase the complexity of the requirements to be considered. As a case study, we present a Bluetooth application that has been developed to fulfill a variety of established requirements. The application allows the creation of different types of networks for non-expert users thanks to the context-aware capacity of Bluetooth.