Platinum Electrodeposition in an Ionic Liquid Analogue. Solvent Stability Monitoring

The use of ionic liquid analogues as solvents has increased in order to substitute the aqueous solvents in some applications in which the side reactions are undesirable. However these solvents prepared from the mixture in the eutectic proportion of species establishing hydrogen bonds are susceptible of electrochemical reactions. The study of platinum deposition on vitreous carbon in an ionic liquid analogue (2 urea: choli ne chloride) is presented; the electrochemical study has permitted to interpret the sequence of the metal deposition process and simultaneously to analyze the behavior of the ionic liquid analogue along the process. Reduction reactions of the solvent relat ed both to the electronation of choline and hydrogen formation have been detected. Different substrata have been used in order to test the possibility and the extent of these reactions depending on the nature of material. The results indicate that the feas ible electrochemical window of the substrate/solvent is highly dependent of the kind of substrate; the negative limit is tied by the massive hydrogen reaction, reaction enhanced by the electrocatalytic character of the substrate.

Dynamic electrostatic force microscopy in liquid media

We present the implementation of dynamic electrostatic force microscopy in liquid media. This implementation enables the quantitative imaging of local dielectric properties of materials in electrolyte solutions with nanoscale spatial resolution. Local imaging capabilities are obtained by probing the frequency-dependent and ionic concentration-dependent electrostatic forces at high frequency (>1 MHz), while quantification of the interaction forces is obtained with finite-element numerical calculations. The results presented open a wide range of possibilities in a number of fields where the dielectric properties of materials need to be probed at the nanoscale and in a liquid environment.

Dynamic electrostatic force microscopy in liquid media

We present the implementation of dynamic electrostatic force microscopy in liquid media. This implementation enables the quantitative imaging of local dielectric properties of materials in electrolyte solutions with nanoscale spatial resolution. Local imaging capabilities are obtained by probing the frequency-dependent and ionic concentration-dependent electrostatic forces at high frequency (>1 MHz), while quantification of the interaction forces is obtained with finite-element numerical calculations. The results presented open a wide range of possibilities in a number of fields where the dielectric properties of materials need to be probed at the nanoscale and in a liquid environment.

Alternative technique for biodiesel quality control using an optical fiber long-period grating sensor

We report the use of an optical fiber sensor to measure the soybean oil concentration in samples obtained from the mixture of pure biodiesel and commercial soybean oil. The operation of the device is based on the long-period grating sensitivity to the surrounding medium refractive index, which leads to measurable modifications in the grating transmission spectrum. The proposed analysis method results in errors in the oil concentration of 0.4% and 2.6% for pure biodiesel and commercial soybean oil, respectively. Techniques of total glycerol, dynamic viscosity, density, and hydrogen nuclear magnetic resonance spectroscopy were also employed to validate the proposed method.

High performance liquid chromatography method for quantification of the N-phenylpiperazine derivative LASSBio-579 in rat plasma

A rapid HPLC analytical method was developed and validated for the determination of the N-phenylpiperazine derivative LASSBio-579in plasma rat. Analyses were performed using a C18 column and elution with 20 mM sodium dihydrogen phosphate monohydrate - methanol. The analyte was monitored using a photodiode array detector (257 nm). Calibration curves in spiked plasma were linear over the concentration range of 0.3-8 mg/mL with determination coefficient > 0.99. The lower limit of quantification was 0.3 mg/mL. The applicability of the HPLC method for pharmacokinetic studies was tested using plasma samples obtained after administration of LASSBio-579 to Wistar rats, showing the specificity of the method.

Reconeixement de gestos de la mà amb el sensor Kinect

El reconeixement dels gestos de la mà (HGR, Hand Gesture Recognition) és actualment un camp important de recerca degut a la varietat de situacions en les quals és necessari comunicar-se mitjançant signes, com pot ser la comunicació entre persones que utilitzen la llengua de signes i les que no. En aquest projecte es presenta un mètode de reconeixement de gestos de la mà a temps real utilitzant el sensor Kinect per Microsoft Xbox, implementat en un entorn Linux (Ubuntu) amb llenguatge de programació Python i utilitzant la llibreria de visió artifical OpenCV per a processar les dades sobre un ordinador portàtil convencional. Gràcies a la capacitat del sensor Kinect de capturar dades de profunditat d’una escena es poden determinar les posicions i trajectòries dels objectes en 3 dimensions, el que implica poder realitzar una anàlisi complerta a temps real d’una imatge o d’una seqüencia d’imatges. El procediment de reconeixement que es planteja es basa en la segmentació de la imatge per poder treballar únicament amb la mà, en la detecció dels contorns, per després obtenir l’envolupant convexa i els defectes convexos, que finalment han de servir per determinar el nombre de dits i concloure en la interpretació del gest; el resultat final és la transcripció del seu significat en una finestra que serveix d’interfície amb l’interlocutor. L’aplicació permet reconèixer els números del 0 al 5, ja que s’analitza únicament una mà, alguns gestos populars i algunes de les lletres de l’alfabet dactilològic de la llengua de signes catalana. El projecte és doncs, la porta d’entrada al camp del reconeixement de gestos i la base d’un futur sistema de reconeixement de la llengua de signes capaç de transcriure tant els signes dinàmics com l’alfabet dactilològic.

Sensor Fusion of Proprioception, Force and Vision in Estimation and Robot

Sensor-based robot control allows manipulation in dynamic environments with uncertainties. Vision is a versatile low-cost sensory modality, but low sample rate, high sensor delay and uncertain measurements limit its usability, especially in strongly dynamic environments. Force is a complementary sensory modality allowing accurate measurements of local object shape when a tooltip is in contact with the object. In multimodal sensor fusion, several sensors measuring different modalities are combined to give a more accurate estimate of the environment. As force and vision are fundamentally different sensory modalities not sharing a common representation, combining the information from these sensors is not straightforward. In this thesis, methods for fusing proprioception, force and vision together are proposed. Making assumptions of object shape and modeling the uncertainties of the sensors, the measurements can be fused together in an extended Kalman filter. The fusion of force and visual measurements makes it possible to estimate the pose of a moving target with an end-effector mounted moving camera at high rate and accuracy. The proposed approach takes the latency of the vision system into account explicitly, to provide high sample rate estimates. The estimates also allow a smooth transition from vision-based motion control to force control. The velocity of the end-effector can be controlled by estimating the distance to the target by vision and determining the velocity profile giving rapid approach and minimal force overshoot. Experiments with a 5-degree-of-freedom parallel hydraulic manipulator and a 6-degree-of-freedom serial manipulator show that integration of several sensor modalities can increase the accuracy of the measurements significantly.

Recovery of organic acids with liquid-liquid extraction contactors

Liquid-liquid extraction is a mass transfer process for recovering the desired components from the liquid streams by contacting it to non-soluble liquid solvent. Literature part of this thesis deals with theory of the liquid-liquid extraction and the main steps of the extraction process design. The experimental part of this thesis investigates the extraction of organic acids from aqueous solution. The aim was to find the optimal solvent for recovering the organic acids from aqueous solutions. The other objective was to test the selected solvent in pilot scale with packed column and compare the effectiveness of the structured and the random packing, the effect of dispersed phase selection and the effect of packing material wettability properties. Experiments showed that selected solvent works well with dilute organic acid solutions. The random packing proved to be more efficient than the structured packing due to higher hold-up of the dispersed phase. Dispersing the phase that is present in larger volume proved to more efficient. With the random packing the material that was wetted by the dispersed phase was more efficient due to higher hold-up of the dispersed phase. According the literature, the behavior is usually opposite.

Performance characteristics of bioassay UV-spectrophotometry and high perfomance liquid chromatographic determination of gatifloxacin in tablets

The microbiological bioassay, UV-spectrophotometry and HPLC methods for assaying gatifloxacin in tablets were compared. Validation parameters such as linearity, precision, accuracy, limit of detection and limit of quantitation were determined. Beer's law was obeyed in the ranges 4.0-14.0 μg/mL for HPLC and UV-spectrophotometric method, and 4.0-16.0 μg/mL for bioassay. All methods were reliable within acceptable limits for antibiotic pharmaceutical preparations being accurate, precise and reproducible. The bioassay and HPLC are more specific than UV-spectrophotometric analysis. The application of each method as a routine analysis should be investigated considering cost, simplicity, equipment, solvents, speed, and application to large or small workloads.

Highly selective transport of mercury(II) ion through a bulk liquid membrane

In this work carrier-facilitated transport of mercury(II) against its concentration gradient from aqueous 0.04 M hydrochloric acid solution across a liquid membrane containing isopropyl 2-[(isopropoxycarbothiolyl)disulfanyl]ethane thioate (IIDE) as the mobile carrier in chloroform has been investigated. Sodium thiocyanate solution (1.6 M) was the most efficient receiving phase agent among several aqueous reagents tested. Various parameters such as investigated. Under optimum conditions the transport of Hg(II) across the liquid membrane is more than 97% after 2.5 h. The carrier, IIDE, selectively and efficiently could able to transport Hg (II) ions in the presence of other associated metal ions in binary systems.

Quantitative determination of acetaminophen, phenylephrine and carbinoxamine in tablets by high-performance liquid chromatography

An alternative methodology for analysis of acetaminophen (Ace), phenylephrine (Phe) and carbinoxamine (Car) in tablets by ion-pair reversed phase high performance liquid chromatography was validated. The pharmaceutical preparations were analyzed by using a C18 column (5 μm, 300 mm, 3.9 mm) and mobile phase consisting of 60% methanol and 40% potassium monobasic phosphate aqueous solution (62.46 mmol L-1) added with 1 mL phosphoric acid, 0.50 mL triethylamine and 0.25 g sodium lauryl sulfate. Isocratic analysis was performed under direct UV detection at 220 nm for Phe and Car and at 300 nm for Ace within 5 min.

Determination of phenobarbital in human plasma by a specific liquid chromatography method: application to a bioequivalence study

A liquid chromatography method was developed and validated for the determination of phenobarbital in human plasma using phenytoin as internal standard. The drugs were extracted from plasma by liquid-liquid extraction and separated isocratically on a C12 analytical column, maintained at 35 ºC, with water:acetonitrile:methanol (58.8:15.2:26, v/v/v) as mobile phase, run at a flow rate of 1.2 mL/min with detection at 205 nm. The method was linear in the range of 0.1-4 μg/mL (r²=0.9999) and demonstrated acceptable results for the precision, accuracy and stability studies. The method was successfully applied for the bioequivalence study of two tablet formulations (test and reference) of phenobarbital 100 mg after single oral dose administration to healthy human volunteers.

Determination of free urinary cortisol in cushing's syndrome using reversed-phase high performance liquid chromatography

Determination of free urinary cortisol is a test of choice in the diagnosis of Cushing's syndrome. In this study, cortisol was quantified using reversed-phase high-performance liquid chromatography (RP-HPLC) in urine samples previously extracted with ether and using triamcinolone acetonide as internal standard (IS). A BDS-Hypersil-C18® column, water-acetonitrile (72:28; v/v), with a flow rate of 1.0 mL/min and detection at 243 nm were used. This method showed to be both effective and efficient, with sensitivity and linearity ranging from 2.50 to 150 μg/L, and can be used in substitution to the radioimmunoassay technique within this concentration range.

Possibilidades e limitações no uso da temperatura em cromatografia líquida de fase reversa

High-temperature liquid chromatography (HTLC) is a technique that presents a series of advantages in liquid phase separations, such as: reduced analysis time, reduced pressure drop, reduced asymmetry factors, modified retentions, controlled selectivities, better efficiencies and improved detectivities, as well as permitting green chromatography. The practical limitations that relate to instrumentation and to stationary phase instability are being resolved and this technique is now ready to be applied for routine determinations.

Internal standard versus external standard calibration: an uncertainty case study of a liquid chromatography analysis

Traditionally, in the cigarettes industry, the determination of ammonium ion in the mainstream smoke is performed by ion chromatography. This work studies this determination and compares the results of this technique with the use of external and internal standard calibration. A reference cigarette sample presented measurement uncertainty of 2.0 μg/cigarette and 1.5 μg/cigarette, with external and internal standard, respectively. It is observed that the greatest source of uncertainty is the bias correction factor and that it is even more significant when using external standard, confirming thus the importance of internal standardization for this correction.