Development of a fast capillary electrophoresis method for the determination of propranolol-Total analysis time reduction strategies

The aim of this study was to develop a fast capillary electrophoresis method for the determination of propranolol in pharmaceutical preparations. In the method development the pH and constituents of the background electrolyte were selected using the effective mobility versus pH curves. Benzylamine was used as the internal standard. The background electrolyte was composed of 60 mmol L(-1) tris(hydroxymethyl)aminomethane and 30 mmol L(-1) 2-hydroxyisobutyric acid,at pH 8.1. Separation was conducted in a fused-silica capillary (32 cm total length and 8.5 cm effective length, 50 mu m I.D.) with a short-end injection configuration and direct UV detection at 214 nm. The run time was only 14 s. Three different strategies were studied in order to develop a fast CE method with low total analysis time for propranolol analysis: low flush time (Lflush) 35 runs/h, without flush (Wflush) 52 runs/h, and Invert (switched polarity) 45 runs/h. Since the three strategies developed are statistically equivalent, Mush was selected due to the higher analytical frequency in comparison with the other methods. A few figures of merit of the proposed method include: good linearity (R(2) > 0.9999); limit of detection of 0.5 mg L(-1): inter-day precision better than 1.03% (n = 9) and recovery in the range of 95.1-104.5%. (C) 2009 Elsevier B.V. All rights reserved.

Rapid method for the determination. of organic acids in wine by capillary electrophoresis with indirect UV detection

A capillary electrophoresis method for organic acids in wine was developed and validated. The optimal electrolyte consisted of 10 mmol/L 3,5-dinitrobenzoic acid (DNB) at pH 3.6 containing 0.2 mmol/L cetyltrimethylammonium bromide as flow reverser. DNB was chosen because it has an effective mobility similar to the organic acids under investigation, good buffering capacity at pH 3.6, and good chromophoric characteristics for indirect UV-absorbance detection at 254 nm. Sample preparation involved dilution and filtration. The method showed good performance characteristics: Linearity at 6 to 285 mg/L (r > 0.99); detection and quantification limits of 0.64 to 1.55 and 2.12 to 5.15 mg/L, respectively; separation time of less than 5.5 min. Coefficients of variation for ten injections were less than 5% and recoveries varied from 95% to 102%. Application to 23 samples of Brazilian wine confirmed good repeatability and demonstrated wide variation in the organic acid concentrations. (C) 2008 Elsevier Ltd. All rights reserved.

Pt film electrodes prepared by the Pechini method for electrochemical decolourisation of Reactive Orange 16

Electrochemical decolourisation of Reactive Orange 16 was carried out in an electrochemical flow-cell, using as working electrodes a Pt thin film deposited on a Ti substrate (Pt/Ti) prepared by the Pechini method and a pure platinum (Pt) foil. Using the Pt/Ti electrodes better results for dye decolourisation were obtained under milder conditions than those used for pure Pt. For the Pt electrode, colour removal of 93 % (lambda = 493 nm) was obtained after 60 min, at 2.2 V vs. RHE, using 0.017 mol L(-1) NaCl + 0.5 mol L(-1) H(2)SO(4) solution. For the Pt/Ti electrode there was better colour removal, 98%, than for the Pt electrode. Moreover, we used 0.017 mol L(-1) NaCl solution and the applied potential was 1.8 V. Under this condition after 15 min of electrolysis, more than 80% of colour was removed. The rate reaction constant, assuming a first order reaction, was 0.024 min(-1) and 0.069 min(-1), for Pt and Pt/Ti electrodes, respectively.

Study of ethanol electro-oxidation in acid environment on Pt(3)Sn/C anode catalysts prepared by a modified polymeric precursor method under controlled synthesis conditions

A carbon-supported binary Pt(3)Sn catalyst has been prepared using a modified polymeric precursor method under controlled synthesis conditions This material was characterized using X-ray diffraction (XRD). and the results indicate that 23% (of a possible 25%) of Sn is alloyed with Pt, forming a dominant Pt(3)Sn phase. Transmission election microscopy (TEM) shows good dispersion of the electrocatalyst and small particle sizes (3 6 nm +/- 1 nm) The polarization curves for a direct ethanol fuel cell using Pt(3)Sn/C as the anode demonstrated Improved performance compared to that of a PtSn/C E-TEK. especially in the intrinsic resistance-controlled and mass transfer regions. This behavior is probably associated with the Pt(3)Sn phase. The maximum power density for the Pt(3)Sn/C electrocatalyst (58 mW cm(-2)) is nearly twice that of a PtSn/C E-TEK electrocatalyst (33 mW cm(-2)) This behavior is attributed to the presence of a mixed Pt(9)Sn and Pt(3)Sn alloy phase in the commercial catalysts (C) 2009 Elsevier B V All rights reserved

Anticorrosive cerium-based coatings prepared by the sol-gel method

The development of efficient anti-corrosion and environmentally friendly coating systems are needed for the replacement of the highly toxic Cr-based conversion coatings for corrosion protection of aluminum alloys. In this study, we demonstrate that the direct application of ceramic cerium-based sol-gel coatings to AA7075-T6 substrates produces high-performance anti-corrosion layers. Electrochemical experiments and analyses of the microstructure demonstrate that the protective layers are very efficient for the passivation of the alloy surfaces operating as both passive and active barrier for corrosion protection.

Ethanol oxidation reaction on PtCeO(2)/C electrocatalysts prepared by the polymeric precursor method

This paper presents a study of the electrocatalysis of ethanol oxidation reactions in an acidic medium on Pt-CeO(2)/C (20 wt.% of Pt-CeO(2) on carbon XC-72R), prepared in different mass ratios by the polymeric precursor method. The mass ratios between Pt and CeO(2) (3:1, 2:1, 1:1, 1:2, 1:3) were confirmed by Energy Dispersive X-ray Analysis (EDAX). X-ray diffraction (XRD) structural characterization data shows that the Pt-CeO(2)/C catalysts are composed of nanosized polycrystalline non-alloyed deposits, from which reflections corresponding to the fcc (Pt) and fluorite (CeO(2)) structures were clearly observed. The mean crystallite sizes calculated from XRD data revealed that, independent of the mass ratio, a value close to 3 nm was obtained for the CeO(2) particles. For Pt, the mean crystallite sizes were dependent on the ratio of this metal in the catalysts. Low platinum ratios resulted in small crystallites. and high Pt proportions resulted in larger crystallites. The size distributions of the catalysts particles, determined by XRD, were confirmed by Transmission Electron Microscope (TEM) imaging. Cyclic voltammetry and chronoamperometic experiments were used to evaluate the electrocatalytic performance of the different materials. In all cases, except Pt-CeO(2)/C 1:1, the Pt-Ceo(2)/C catalysts exhibited improved performance when compared with Pt/C. The best result was obtained for the Pt-CeO(2)/C 1:3 catalyst, which gave better results than the Pt-Ru/C (Etek) catalyst. (C) 2009 Elsevier B.V. All rights reserved.

Study of photo-assisted electrochemical degradation of carbaryl at dimensionally stable anodes (DSA (R))

This paper presents the results concerning the degradation of the pesticide carbaryl comparing two methods: electrochemical (EC) and photo-assisted electrochemical (PAEC). The experimental variables of applied current density, electrolyte flow-rate and initial carbaryl concentration were investigated. The results demonstrate that the electrochemical degradation of carbaryl was greatly enhanced when simultaneous UV light was applied. The greatest difference between the PAEC and EC method was apparent when lower current densities were applied. The extent of COD removal was much enhanced for the combined method, independent of the applied current density. It should be noted that the complete removal of carbaryl was achieved with out the need to add NaCl to the reaction mixture, avoiding the risk of chlorinated organic species formation. (C) 2009 Elsevier B.V. All rights reserved.

Carbon supported electrocatalysts prepared by the sol-gel method and their utilization for the oxidation of methanol in acid media

One of the key objectives in fuel-cell technology is to improve the performance of the anode catalyst for the alcohol oxidation and reduce Pt loading. Here, we show the use of six different electrocatalysts synthesized by the sol -gel method on carbon powder to promote the oxidation of methanol in acid media. The catalysts Pt-PbO(x) and Pt-(RuO(2)-PbO(x)) with 10% of catalyst load exhibited significantly enhanced catalytic activity toward the methanol oxidation reaction as compared to Pt-(RuO(2))/C and Pt/C electrodes. Cyclic voltammetry studies showed that the electrocatalysts Pt-PbO(x)/C and Pt-(RuO(2)-PbO(x))/C started the oxidation process at extremely low potentials and that they represent a good novelty to oxidize methanol. Furthermore, quasi-stationary polarization experiments and cronoamperometry studies showed the good performance of the Pt-PbO(x), Pt-(RuO(2)-PbO(x))/C and Pt-(RuO(2)-IrO(2))/C catalysts during the oxidation process. Thus, the addition of metallic Pt and PbO(x) onto high-area carbon powder, by the sol -gel route, constitutes an interesting way to prepare anodes with high catalytic activity for further applications in direct methanol fuel cell systems.

Evaluation of the QuEChERS Method and Gas Chromatography-Mass Spectrometry for the Analysis Pesticide Residues in Water and Sediment

A method for the determination of pesticide residues in water and sediment was developed using the QuEChERS method followed by gas chromatography - mass spectrometry. The method was validated in terms of accuracy, specificity, linearity, detection and quantification limits. The recovery percentages obtained for the pesticides in water at different concentrations ranged from 63 to 116%, with relative standard deviations below 12%. The corresponding results from the sediment ranged from 48 to 115% with relative standard deviations below 16%. The limits of detection for the pesticides in water and sediment were below 0.003 mg L(-1) and 0.02 mg kg(-1), respectively.

Det är värre att inte börja studera än att hoppa av: En fenomenologisk studie om hur icke traditionella studenter upplever studieavhopp från högskoleutbildning

In Sweden we have the highest rate of nontraditional students among Europe. Coincidently, we also have the highest rates of drop outs among OECD. In this particular field, drop out from higher education, there is a need fore more qualitative studies that can support the "statistics". Studies about experiences of drop outs are significant for society, university and individual. The aim of this study is to describe and understand how nontraditional student experiences drop out from higher education. What do they tell regarding their meeting with the university? How is the drop out visible before the decision to quit? How can the way forward to the drop out be described? What does the university mean for them? The theoretical point of departure is the concept lifeworld and the method is phenomenological hermeneutic with narrative interviews with 5 students. The result points out that the meeting with the university implies a meeting with other individuals, and also a "meeting" within the student himself, by inner questioning and reflection. The students’ relationship to the studies is characterized by the experience of understanding. The dropouts are visible through different events. The decision per se has increased over time and the students have also grown personally by the decision. To understand or not understand is crucial for the experience of learning. The drop out can also be seen as a transition and a turning point. The drop out is an effort and takes place without professional staff, therefore needs to be discussed in public.

Förlossningsrädda kvinnors erfarenheter av Aurorasamtal ett till två år efter förlossning

Bakgrund: Av alla gravida kvinnor räknas omkring 5 % lida av svår förlossningsrädsla. Kvinnor med förlossningsrädsla löper högre risk för komplikationer under och efter graviditeten. I Sverige läggs idag mycket resurser på Auroraverksamhet för att hjälpa kvinnor med förlossningsrädsla. Det saknas omfattande utvärdering av Auroraverksamheten. Syfte: Syftet med detta fördjupningsarbete var att undersöka upplevelse och effekt av Aurorasamtal inför förlossning samt upplevelse av den efterföljande förlossningen bland först- och omföderskor. Metod: Studien har en retrospektiv studiedesign där datainsamling skedde via en enkätundersökning. Datamaterialet sammanställdes därefter i SPSS. Resultat: Majoriteten av kvinnorna upplevde att samtalen hjälpte dem till en mer positiv förlossningsupplevelse. Fler förstföderskor än omföderskor önskade planerat kejsarsnitt när de kom till Auroramottagningen. De flesta kvinnor som önskade vaginal förlossning blev vaginalt förlösta. Över hälften av kvinnorna som deltog i studien var mindre rädda för förlossning 1 – 2 år efter förlossningen än de upplevde att de var innan Aurorasamtalet och förlossningen. Konklusion: Aurorasamtal förefaller ha störst betydelse för omföderskor och för de kvinnor som önskar vaginal förlossning.

Vad ska elever lära sig angående naturvetenskaplig verksamhet? : En analys av svenska läroplaner för grundskolan under 50 år

The purpose of this study is to contribute to an understanding of which changes related to scientific inquiry have been made historically in curriculum documents. A comparative analysis is made of five Swedish national curricula– Lgr 62, Lgr 69, Lgr 80, Lpo 94 and Lgr 11 – during the last 50 years regarding what compulsory school students (school years 1–9) should learn about scientific inquiry. It focuses 1) what students should learn about carrying out scientific inquiries, and 2) what students should learn about the nature of science. All of the curricula examined have aims concerning scientific inquiry. The results show that during the period there have been many shifts in emphasis and changes of aims, for example from learning an inductive method to a more deductive one, and from an emphasis on carrying out investigations to an emphasis on more conceptual understanding of scientific investigations. Because teaching traditions tend to conserve aspects of earlier curricula, it is discussed how the results can help teachers, teacher students and curriculum developers to better see the consequences of the changes for teaching and learning.

Det är enklare i teorin… Om skolutveckling i praktiken : En fallstudie av ett skolutvecklingsprojekt i en gymnasieskola

This dissertation is a case study dealing with a school development project that took place in an upper secondary school as a result of a merger of two schools with different cultures. The project used a method called “Frirumsmodellen” and was planned to be conducted in three steps. The first was to carry out a cultural analysis in order to map the preconditions to start a school development project. The second was to carry out concrete actions and finally study eventual effects from such activities by doing a second cultural analysis. My role was to be a supervisor in the school development work, but at the same time study how this work was conducted and its impact in the ordinary school day. The dissertation takes its departure in the fact that schools are political governed. The mission of schools is never neutral; it is always an expression of behind laying social forces, ideologies and ideals of the contemporary society. Of this reason, there is a close connection between the macro political level and the micro political level. Another point of departure is the transition from a modern to a post modern society that gives the character to the changes that take place in schools. Steering of schools has partly been treated as a technical implementation problem. Schools contain on going conflicts between different interest groups that, more or less regularly, end up in educational reforms. These reforms generate school development activities in the single school. Undoubtedly, this makes school development to a complex process. At a rather late stage of the study I decided not to fulfil my task to follow the original plan. I instead let the school development project as a model to be in focus. The over all purpose was formulated: How is it possible to understand what happened in the school development project in the Falkgymnasiet and why was it not possible to carry it out as it was said in the project plan? To interpret what took place during the project I did create an interpretation frame of implementation and complexity theory that also made it possible to critically scrutinise the “Frirumsmodellen”. Already in an early stage of the process it was obvious that the “Frirumsmodellen” did not supply any tools to use and it became disconnected from the project. The project in it selves was marginalised and made invisible. The headmaster used the situation to change things she thought were important to develop. As a result, things happened, but most of the involved people did not at first hand connect this to the project. It is, of course, difficult in detail to say what caused what. The complexity theory successively made the hidden patterns revealed, hidden unofficial potentates visible, as well as unpredictable conditions that generated reactions from the personnel in front of a development work. Together this was rather efficient obstacles for not changing this school. I also discuss school development and implementation problems on a general level, for example, the possibility to transform a top-down initiated project to be bottom-up driven and using project as a tool for school development work. It was obvious that headmasters and teachers must be prepared to handle the ideological dimensions of problems schools have to face. Consequently, development work is about making problems visible and to handle these in the intersection point between the intentions of educational policies, pedagogical researchers, school administrators, headmasters, teachers and pupils. The ideological dimension also contains an existential issue. Do I as a teacher share the intentions for the development work? If not, how must I act?

Mechanical and tribological properties of PVD-coated cemented carbide as evaluated by a new multi-pass scratch testing method

A new test method based on multipass scratch testing has been developed for evaluating the mechanical and tribological properties of thin, hard coatings. The proposed test method uses a pin-on-disc tribometer and during testing a Rockwell C diamond stylus is used as the “pin” and loaded against the rotating coated sample. The influence of normal load on the number of cycles to coating damage is investigated and the resulting coating damage mechanisms are evaluated by posttest scanning electron microscopy. The present study presents the test method by evaluating the performance of Ti0.86Si0.14N, Ti0.34Al0.66N, and (Al0.7Cr0.3)2O3 coatings deposited by cathodic arc evaporation on cemented carbide inserts. The results show that the test method is quick, simple, and reproducible and can preferably be used to obtain relevant data concerning the fatigue, wear, chipping, and spalling characteristics of different coating-substrate composites. The test method can be used as a virtually nondestructive test and, for example, be used to evaluate the fatigue and wear resistance as well as the cohesive and adhesive interfacial strength of coated cemented carbide inserts prior to cutting tests.

Qualificação de edifícios residenciais verticais em Natal/RN à luz do regulamento técnico da qualidade para o nível de eficiência energética de edificações residenciais (RTQ-R)

The goal of the research was to investigate the energy performance of residential vertical buildings envelope in the hot and humid climate of Natal, capital of Rio Grande do Norte, based in the Technical Regulation of Quality for Energy Efficiency Level in Residential Buildings (RTQ -R), launched in 2010. The study pretends to contribute to the development of design strategies appropriate to the specific local climate and the increasing of energy efficiency level of the envelope. The methodological procedures included the survey in 22 (twenty two) residential buildings, the formulation of representative prototypes based on typological and constructives characters researched and the classification of the level of energy efficiency in the envelopment of these prototypes, using as a tool the prescriptive method of the RTQ-R and the parametric analyzes from assigning different values of the following variables: shape of the pavement type; distribution of housing compartments; orientation of the building; area and shading of openings; thermal transmittance, and solar absorptance of opaque materials of the frontage in order to evaluate the influence of these on the envelopment performance. The main results accomplished with this work includes the qualification of vertical residential buildings in Natal/RN; the verification of the adequacy of these buildings to local climate based from the diagnosis of the thermal energy of the envelopment performance, the identification of variables with more significant influence on the prescriptive methodology of RTQ-R and design solutions more favorable to obtain higher levels energy efficiency by this method. Finally, it was verified, that some of these solutions proved contradictory in relation to the recommendations contained in the theoretical approaches regarding environmental comfort in hot and humid weather, which indicates the need for improvement of the prescriptive method RTQ-R and further research on efficient design solutions