Técnicas de estudio en estudiantes de Secundaria que asisten a clases extraescolares en la provincia de Girona

Study techniques in out of school secondary education in the province of Girona. It is important to provide students with different ways to study so they can find the most appropriate method for them. Our research focuses on the study techniques used in secondary education by those students attending classes out of school time. In order to conduct this research, we have developed a general questionnaire after reviewing the existing literature on the topic. Some of the results obtained with this study are the following: adolescents attach great importance to learn study techniques, being summaries, diagrams and underlining the most well-known strategies for them, and mind maps and teamwork the least popular ones; they prefer dynamic teaching and learning methodologies, such as making interactive discussions; tutoring is the most valued element. Based on the results obtained with the study, we have developed some proposals to facilitate the work of the teacher when teaching study techniques and helping students to improve their academic performance

A Headspace needle-trap method for the analysis of volatile organic compounds in whole blood

Needle trap devices (NTDs) are a relatively new and promising tool for headspace (HS) analysis. In this study, a dynamic HS sampling procedure is evaluated for the determination of volatile organic compounds (VOCs) in whole blood samples. A full factorial design was used to evaluate the influence of the number of cycles and incubation time and it is demonstrated that the controlling factor in the process is the number of cycles. A mathematical model can be used to determine the most appropriate number of cycles required to adsorb a prefixed amount of VOCs present in the HS phase whenever quantitative adsorption is reached in each cycle. Matrix effect is of great importance when complex biological samples, such as blood, are analyzed. The evaluation of the salting out effect showed a significant improvement in the volatilization of VOCs to the HS in this type of matrices. Moreover, a 1:4 (blood:water) dilution is required to obtain quantitative recoveries of the target analytes when external calibration is used. The method developed gives detection limits in the 0.020–0.080 μg L−1 range (0.1–0.4 μg L−1 range for undiluted blood samples) with appropriate repeatability values (RSD < 15% at high level and <23% at LOQ level). Figure of merits of the method can be improved by using a smaller phase ratio (i.e., an increase in the blood volume and a decrease in the HS volume), which lead to lower detection limits, better repeatability values and greater sensibility. Twenty-eight blood samples have been evaluated with the proposed method and the results agree with those indicated in other studies. Benzene was the only target compound that gave significant differences between blood levels detected in volunteer non-smokers and smokers

On Commutation and Conjugacy of Rational Languages and the Fixed Point Method

The research on language equations has been active during last decades. Compared to the equations on words the equations on languages are much more difficult to solve. Even very simple equations that are easy to solve for words can be very hard for languages. In this thesis we study two of such equations, namely commutation and conjugacy equations. We study these equations on some limited special cases and compare some of these results to the solutions of corresponding equations on words. For both equations we study the maximal solutions, the centralizer and the conjugator. We present a fixed point method that we can use to search these maximal solutions and analyze the reasons why this method is not successful for all languages. We give also several examples to illustrate the behaviour of this method.

Azolium-based systems: application of an anion exchange resin (A- form) method and 1H NMR analysis of the charged-assisted (CH)+·anion hydrogen bonds

The counteranion exchange of quaternary 1,2,3-triazolium salts was examined using a simple method that permitted halide ions to be swap for a variety of anions using an anion exchange resin (A¯ form). The method was applied to 1,2,3-triazolium-based ionic liquids and the iodideto- anion exchange proceeded in excellent to quantitative yields, concomitantly removing halide impurities. Additionally, an anion exchange resin (N3¯ form) was used to obtain the benzyl azide from benzyl halide under mild reaction. Likewise, following a similar protocol, bis(azidomethyl)arenes were also synthesized in excellent yields. The results of a proton NMR spectroscopic study of simple azolium-based ion pairs are discussed, with attention focused on the significance of the charged-assisted (CH)+···anion hydrogen bonds of simple azolium systems such as 1-butyl-3-methylimidazolium and 1-benzyl-3-methyl-1,2,3-triazolium salts.

Azolium-based systems: application of an anion exchange resin (A- form) method and 1H NMR analysis of the charged-assisted (CH)+·anion hydrogen bonds

The counteranion exchange of quaternary 1,2,3-triazolium salts was examined using a simple method that permitted halide ions to be swap for a variety of anions using an anion exchange resin (A¯ form). The method was applied to 1,2,3-triazolium-based ionic liquids and the iodideto- anion exchange proceeded in excellent to quantitative yields, concomitantly removing halide impurities. Additionally, an anion exchange resin (N3¯ form) was used to obtain the benzyl azide from benzyl halide under mild reaction. Likewise, following a similar protocol, bis(azidomethyl)arenes were also synthesized in excellent yields. The results of a proton NMR spectroscopic study of simple azolium-based ion pairs are discussed, with attention focused on the significance of the charged-assisted (CH)+···anion hydrogen bonds of simple azolium systems such as 1-butyl-3-methylimidazolium and 1-benzyl-3-methyl-1,2,3-triazolium salts.

Azolium-based systems: application of an anion exchange resin (A- form) method and 1H NMR analysis of the charged-assisted (CH)+·anion hydrogen bonds

The counteranion exchange of quaternary 1,2,3-triazolium salts was examined using a simple method that permitted halide ions to be swap for a variety of anions using an anion exchange resin (A¯ form). The method was applied to 1,2,3-triazolium-based ionic liquids and the iodideto- anion exchange proceeded in excellent to quantitative yields, concomitantly removing halide impurities. Additionally, an anion exchange resin (N3¯ form) was used to obtain the benzyl azide from benzyl halide under mild reaction. Likewise, following a similar protocol, bis(azidomethyl)arenes were also synthesized in excellent yields. The results of a proton NMR spectroscopic study of simple azolium-based ion pairs are discussed, with attention focused on the significance of the charged-assisted (CH)+···anion hydrogen bonds of simple azolium systems such as 1-butyl-3-methylimidazolium and 1-benzyl-3-methyl-1,2,3-triazolium salts.

Validated spectrofluorometric method for determination of gemfibrozil in self nanoemulsifying drug delivery systems (SNEDDS)

A spectrofluorometric method has been developed and validated for the determination of gemfibrozil. The method is based on the excitation and emission capacities of gemfibrozil with excitation and emission wavelengths of 276 and 304 nm respectively. This method allows de determination of the drug in a self-nanoemulsifying drug delivery system (SNEDDS) for improve its intestinal absorption. Results obtained showed linear relationships with good correlation coefficients (r(2)>0.999) and low limits of detection and quantification (LOD of 0.075 μg mL(-1) and LOQ of 0.226 μg mL(-1)) in the range of 0.2-5 μg mL(-1), equally this method showed a good robustness and stability. Thus the amounts of gemfibrozil released from SNEDDS contained in gastro resistant hard gelatine capsules were analysed, and release studies could be performed satisfactorily.

Radio Frequency Measurement Method for Detecting Bearing Currents in Induction Motors

Induction motors are widely used in industry, and they are generally considered very reliable. They often have a critical role in industrial processes, and their failure can lead to significant losses as a result of shutdown times. Typical failures of induction motors can be classified into stator, rotor, and bearing failures. One of the reasons for a bearing damage and eventually a bearing failure is bearing currents. Bearing currents in induction motors can be divided into two main categories; classical bearing currents and inverter-induced bearing currents. A bearing damage caused by bearing currents results, for instance, from electrical discharges that take place through the lubricant film between the raceways of the inner and the outer ring and the rolling elements of a bearing. This phenomenon can be considered similar to the one of electrical discharge machining, where material is removed by a series of rapidly recurring electrical arcing discharges between an electrode and a workpiece. This thesis concentrates on bearing currents with a special reference to bearing current detection in induction motors. A bearing current detection method based on radio frequency impulse reception and detection is studied. The thesis describes how a motor can work as a “spark gap” transmitter and discusses a discharge in a bearing as a source of radio frequency impulse. It is shown that a discharge, occurring due to bearing currents, can be detected at a distance of several meters from the motor. The issues of interference, detection, and location techniques are discussed. The applicability of the method is shown with a series of measurements with a specially constructed test motor and an unmodified frequency-converter-driven motor. The radio frequency method studied provides a nonintrusive method to detect harmful bearing currents in the drive system. If bearing current mitigation techniques are applied, their effectiveness can be immediately verified with the proposed method. The method also gives a tool to estimate the harmfulness of the bearing currents by making it possible to detect and locate individual discharges inside the bearings of electric motors.

Lukion opettajien ääni - Aineenopettajien käsityksiä muutoksista ja visioista lukiossa

Tulevaisuusorientaatio on tullut entistä tärkeämmäksi myös koulumaailmassa johtuen yhteiskunnassa nopeasti eteen tulevista muutoksista. On myös esitetty epäilyjä, että tulevaisuuteen reagoimisessa heikoin tilanne olisikin juuri kuntatason päätöksenteossa. Ymmärrys ja tieto opettajan työstä nimenomaan opettajan omasta perspektiivistä tarkasteltuna mahdollistavat lähtökohdan ja edellytykset todelliselle koulun uudistamiselle. Peruskysymys, johon tässä tutkimuksessa etsittiin vastausta oli: Millaisia ovat lukion aineenopettajien käsitykset lukion muutosprosesseista ja miten he visioivat oman lukionsa ja yleensä lukioiden tulevaisuutta? Aineiston keruu osui ajankohtaan, joka oli hyvin otollinen tulevaisuuden tarkasteluun, sillä uusi opetussuunnitelma otettiin käyttöön kaikissa Suomen lukioissa viimeistään lukuvuonna 2005-2006. Tutkimuksessa oli mukana kaksi hyvin erilaista lukiota Länsi-Suomen läänistä eli pieni maaseudun lukio ja hyvin suuri kaupunkilukio. Tutkimusaineiston keruu eteni kaksivaiheisesti: informoitu kysely ja teemahaastattelu. Tutkimusjoukon suuruus oli yhteensä 20, joista puolet oli miehiä ja puolet naisia. Aineenopettajien käsityksiä muutoksista ja visioista tutkittiin fenomenografisen tutkimusotteen avulla. Fenomenografiassa kiinnostuksen kohteena ovat ihmisten erilaiset käsitykset todellisuudesta ja näin saatava ymmärrys tavoista, joilla ihmiset kokevat tilanteita ja maailmaa. Organisaation muutosprosesseja voidaan kutsua myös oppimiseksi. Tutkimuksen oppivan organisaation näkökulmat perustuivat juuri yhteistyössä tapahtuvaan yhteisen toiminnan kehittämiseen. Aineenopettajien käsityksiä työyhteisöstään tarkasteltiin seuraavista oppivan organisaatiomallin näkökulmista: vuorovaikutus, päätöksenteko sekä rehtorin ja aineenopettajan rooli ja asema työyhteisössä. Aineenopettajien keskeisimmät käsitykset muutoksista lukiossa viime vuosina kohdistuivat aineenopettajan ammattirooliin ja lukio-opiskelijaan sekä opiskelijalta vaadittaviin lukio-opintoihin. Muutokset ammattiroolissa korostavat tutkimustulosten perusteella aineenopettajilta vaadittavia muitakin kuin opetettavien aineiden hallintataitoja. Suoranaista ammattitaidon puutetta opettajat kokivat varsinkin ryhmänohjaustehtävien yhteydessä, osittain myös uusien oppimisympäristöjen, esimerkiksi verkkopedagogisten taitojen, yhteydessä. Opettajien lisäkoulutuksen tarve koetaan konkreettisena, mutta sekä koulutusten sisältöihin, järjestelyihin ja ajankohtiin että koulun sijais- ym. järjestelyihin kaivattaisiin parannuksia. Verrattuna aikaisempiin tutkimuksiin näyttäisi siltä, että luokaton lukio on saanut opettajat enenevässä määrin huolestumaan opiskelijoiden syrjäytymisriskistä ja hyvinvoinnista. Opiskelijoiden syrjäytymisriskin kasvu lukio-opintojen aikana nouseekin yhdeksi lukion pessimistiseksi skenaarioksi. Muista pessimistisistä skenaarioista lukiolle, jotka saattoi johtaa tutkimustuloksista, voidaan mainita työyhteisön demokratiavajeen syveneminen sekä opetussuunnitelmasisältöjen ja ylioppilastutkintovaatimusten välisen kuilun syveneminen. Aineenopettajien käsitykset oman lukionsa visioista olivat sisällöiltään pääosin välineellisiä ja ne kohdentuivat kaikki opiskelijoihin. Esimerkiksi työyhteisöllisiä kehittämisajatuksia ei visioissa ilmennyt. Myöskään visioinnin dynaamisuus ei aineistossa korostunut. Aineenopettajien käsitykset visioiden arvopohjasta heijastivat perinteistä suomalaista arvomaailmaa eli itsekuria, velvollisuudentuntoa, kuuliaisuutta esivaltaa kohtaan ja perinteisten arvojen kunnioittamista. Sen sijaan antiikista perityviä Sokrateen edustamia keskustelua ja auktoriteettien kyseenalaistamista ei arvoissa ilmennyt, eikä myöskään uusliberalistista individualismia. Käsitykset visioiden synnystä näyttävät parhaiten selittävän opettajan muita käsityksiä liittyen visioon, visiointiin ja työyhteisöllisiin vaikutusmahdollisuuksiin sekä opettajan tulevaisuusorientoitumiseen.. Käsitykset vision syntytaustasta voidaan jakaa seuraaviin pää- ja alakategorioihin: 1. auktoriteettikeskeinen visiointi: johdon linjaus tai valtakunnallinen linjaus, 2. yhteisökeskeinen visiointi: yhteisöllinen linjaus tai toiminnallinen linjaus ja 3. yksilökeskeinen visiointi. Pessimistisimmiksi eli vähiten tulevaisuusorientoituneiksi opettajiksi työyhteisössä osoittautuivat ne opettajat, jotka pitivät oman lukionsa visiota koulun johdon sanelemana. Monet teoriat oppivasta organisaatiosta korostavat johtajuuden merkitystä työyhteisöä kehitettäessä. Johtajuuden merkitys nousi tämänkin tutkimuksen aineistosta keskeisesti esiin. Pyrkimystä kohti oppivaa organisaatiota opettajien puheista löytyy paljonkin, esimerkkeinä viittaukset johtajuuden ja vuorovaikutustapojen kehittämistarpeisiin. Sen sijaan opettajien puheet omista työyhteisöllisistä kehittymistarpeistaan, ns. alaistaidot, jäivät vähäisiksi. Tutkimustuloksista on luotu sovellusmalli kouluyhteisöjen visioinnin ja muun kehittämistyön tueksi.

Electric field calibration method for scanning electron microscope

This paper proposes a calibration method which can be utilized for the analysis of SEM images. The field of application of the developed method is a calculation of surface potential distribution of biased silicon edgeless detector. The suggested processing of the data collected by SEM consists of several stages and takes into account different aspects affecting the SEM image. The calibration method doesn’t pretend to be precise but at the same time it gives the basics of potential distribution when the different biasing voltages applied to the detector.

The attenuation of concentrations model: a new method for assessing mercury mobility in sediments

In this work we propose a new approach for the determination of the mobility of mercury in sediments based on spatial distribution of concentrations. We chose the Tainheiros Cove, located in the Todos os Santos Bay, Brazil, as the study area, for it has a history of mercury contamination due to a chloro-alkali plant that was active during 12 years. Twenty-six surface sediment samples were collected from the area and mercury concentrations were measured by cold vapour atomic absorption spectrophotometry. A contour map was constructed from the results, indicating that mercury accumulated in a "hot spot" where concentrations reach more than 1 µg g-1. The model is able to estimate mobility of mercury in the sediments based on the distances between iso-concentration contours that determines an attenuation of concentrations factor. Values of attenuation ranged between 0.0729 (East of the hot spot, indicating higher mobility) to 0.7727 (North of the hot spot, indicating lower mobility).

Extension of the impedance field method to the noise analysis of a semiconductor junction: Analytical approach

We present an analytical procedure to perform the local noise analysis of a semiconductor junction when both the drift and diffusive parts of the current are important. The method takes into account space-inhomogeneous and hot-carriers conditions in the framework of the drift-diffusion model, and it can be effectively applied to the local noise analysis of different devices: n+nn+ diodes, Schottky barrier diodes, field-effect transistors, etc., operating under strongly inhomogeneous distributions of the electric field and charge concentration

Extension of the impedance field method to the noise analysis of a semiconductor junction: Analytical approach

We present an analytical procedure to perform the local noise analysis of a semiconductor junction when both the drift and diffusive parts of the current are important. The method takes into account space-inhomogeneous and hot-carriers conditions in the framework of the drift-diffusion model, and it can be effectively applied to the local noise analysis of different devices: n+nn+ diodes, Schottky barrier diodes, field-effect transistors, etc., operating under strongly inhomogeneous distributions of the electric field and charge concentration

Development and validation of an alternative titration method for the determination of sulfate ion in indinavir sulfate

A simple and rapid precipitation titration method was developed and validated to determine sulfate ion content in indinavir sulfate raw material. 0.1 mol L-1 lead nitrate volumetric solution was used as titrant employing potentiometric endpoint determination using a lead-specific electrode. The United States Pharmacopoeia Forum indicates a potentiometric method for sulfate ion quantitation using 0.1 mol L-1 lead perchlorate as titrant. Both methods were validated concerning linearity, precision and accuracy, yielding good results. The sulfate ion content found by the two validated methods was compared by the statistical t-student test, indicating that there was no statistically significant difference between the methods.