Electrocatalytic behavior of glassy carbon electrodes modified with multiwalled carbon nanotubes and cobalt phthalocyanine for selective analysis of dopamine in presence of ascorbic acid

This work describes the development, electrochemical characterization and utilization of a cobalt phthalocyanine modified carbon nanotube electrode for the quantitative determination of dopamine in 0.2 mol L-1 phosphate buffer contaminated with high concentration of ascorbic acid. The electrode surface was analyzed by cyclic voltammetry and electrochemical impedance spectroscopy which showed a modified surface presenting a charge transfer resistance of 500 Omega, against the 16.46 k Omega value found for the bare glassy carbon surface. A pseudo rate constant value of 5.4 x 10(-4) cm s(-1) for dopamine oxidation was calculated. Voltammetric experiments showed a shift of the peak potential of DA oxidation to less positive value at 390 mV as compared with that of a bare GC electrode at 570 mV. The electrochemical determination of dopamine, in presence of ascorbic acid in concentrations up to 0.1 mol L-1 by differential pulse voltarnmetry, yielded a detection limit as low as 2.56 x 10(-7) mol L-1.

Effects of starch gelatinization and oxidation on the rheological behavior of chitosan/starch blends

Chitosan/starchblends represent an interesting alternative for the preparation of biocompatible drug delivery systems, packing materials and edible films. This paper reports on the effects of starch gelatinization and oxidation on the rheological behavior of chitosan/starch blends. The results show that the modifications in the starch structure cause changes in G` (storage modulus) and G `` (lossmodulus) as a function of frequency. For chitosan/starch, G `` is higher than G`, showing a viscous behavior. However, for chitosan/gelatinized starch and chitosan/oxidized starch, an increase in the angular frequency promotes a modulus crossover at omega = 0.02 and 0.04 rad s(-1), respectively. The viscosity curves as a function of shear rate show that both modifications cause an increase in viscosity, and all blends show a non-Newtonian behavior. (C) 2011 Society of Chemical Industry

Thermal behavior and structural properites of plant-derived eugenyl acetate

Eugenol is an allyl chain-substituted guaiacol in the biosynthesized phenylpropanoid compound class derived from Syzygium aromaticum L. and widely used in folk medicine. Nonetheless, its pharmacological use is limited by some problems, such as instability when exposed to light and high temperature. In order to enhance stability, the eugenol molecule was structurally modified, resulting in eugenyl acetate. The eugenyl acetate`s thermal behavior and crystal structure was then characterized by differential scanning calorimetry (DSC) and X-ray diffraction (XRD) and compared to a commercial sample.

THERMAL BEHAVIOR OF IN VITRO MINERALIZED ANIONIC COLLAGEN MATRICES

In the present study porcine skin and bovine pericardium were used as a source of type I collagen. Both were submitted to an alkaline treatment and mineralized by the alternate soaking method. Thermal stability and extent of mineralization have been investigated using DSC and TG. After alkaline hydrolysis there is a decrease in thermal stability but mineralization stabilizes collagen structure. Thermogravimetric data have shown that the amount of hydroxyapatite present in bovine pericardium matrix (45%) was greater than on porcine skin matrix (20%). Presence of hydroxyapatite was confirmed by EDX.

Electrochemical Behavior of Verapamil at Graphite-Polyurethane Composite Electrodes: Determination of Release Profiles in Pharmaceutical Samples

A solid graphite-polyurethane composite electrode has been used to determine release profiles of verapamil, a calcium-channel blocker. The electro-oxidation process was characterized by cyclic voltammetry and electrochemical impedance spectroscopy and showed no adsorption of analyte or oxidation products, unlike at other carbon-based electrodes. Quantification gave linear ranges up to 40molL-1 with cyclic voltammetry and detection limits of 0.7molL-1 by differential pulse and square-wave voltammetry. Commercial product samples were successfully analyzed with results equal to those from spectrophotometry. Because no electrode surface renewal is needed, this electrode material has many advantages.

Attityd till att fullfölja nuvarande studier - En applikation av The Theory of Planned Behavior

För att förutsäga och förklara människors beteenden och intentioner har ”attityd” länge varit ett centralt begrepp inom socialpsykologin. En vanlig teori och modell för ändamålet är ”theory of planned behavior” (TpB), vilken säger att en individs beteende styrs av dess intention, som i sin tur är en funktion av den personliga attityden, det sociala trycket och den upplevda kontrollen att kunna genomföra aktuellt beteende. Syftet med föreliggande studie var att undersöka attityden och intentionen till att fullfölja nuvarande studier och göra en applikation av TpB-modellen via en Internetenkät riktad till studenter på Högskolan Dalarna (N = 1292). Hypotesen att ”den upplevda kontrollen” är den viktigaste direkta variabeln för intentionen kunde godtas, vilket kan antagas bero på beteendets karaktär. Diskussion förs också kring intentionens eventuella omvandling till verkligt beteende.

Sustainability & Consumer behavior towards Sustainability in Norway and Sweden

AimSustainability has become an important factor to consider while buying goods and services. People are being more conscious toward environmental impacts of products and services. This attitude has motivated many businesses to develop their production in contact with sustainability. The aim of this paper is to investigate different consumer behaviors toward sustainability in general and in relation to vehicles in Norway and Sweden.ApproachThe project has been embarked by dividing it into two tasks.1. Analyzing past, present and future development, growth and importance of sustainability concept. Describe the role of Government authorities in Norway and Sweden to promote sustainable consumption.2. Investigating important factors of consumer behaviors which influence their buying decision toward sustainable products in general and in relation to sustainable vehicles. Highlight the role of vehicle manufacturing companies to promote sustainable consumption.MethodA research has been conducted in order to explore consumer behavior toward sustainability in Norway and Sweden. Research is based on Document study and primary research which include questionnaire survey with consumers and interviews with vehicle dealers. In addition an expert inquiry is conducted to light up consumer intensions in Norway and Sweden toward sustainability.ResultsThe result of investigation has been revealed in shape of analyses and conclusion at the end. A comparison has been made between primary research and secondary research and findings are overlapping. Sustainable vehicles are being more popular among consumers in Norway and Sweden. Consumption trends are changing over time and environmental friendly attitudes are more developing among Swedish consumers as compared to Norwegian.

Condoms and Healthcare professionals : Risk-behavior and attitudes towards condom use

Alarming S.T.I’s percentages and low condom use motivated this research. Healthcare professional’s risk-behavior and attitudes towards risk-behavior were reviewed. Three hypotheses, aimed to test whether healthcare professionals working with S.T.I’s should have a different attitude, knowledge and behavior to condom use compared to healthcare professionals that did not work with S.T.I’s. Ninety-five participants working at a hospital in middle-Sweden answered a questionnaire, based on the Swedish UNGKAB09 research. Mann-Whitney analyses showed no significant difference between the two groups on knowledge, attitude and behavior. A high percentage of steady relationships, high homogeneity between groups as well the same attitudes and intentions could have been a reliability problem. The collected data was however interesting as a base for further research

Sociala faktorers inverkan på elevers intentioner till högre studier : En applikation av Theory of planned behavior

Denna studie grundar sig på en enkätundersökning av 59 gymnasieungdomars intentioner till att inom de närmaste 5 åren påbörja studier vid högskola eller universitet. Undersökningen är baserad på Theory of planned behavior och syftar till att testa teorins pålitlighet i att besvara vilken av de socialt betingade bakgrundsfaktorerna attityd, subjektiv norm och upplevd beteendekontroll som utgör den bästa prediktorn för undersökningsdeltagarnas intentioner. Därtill undersöks dessa faktorers samband med föräldrarnas utbildningsnivå. Theory of planned behavior visade sig vara ett reliabelt mätinstrument gällande studiens övriga frågor, där den upplevda beteendekontrollen och den subjektiva normen utgjorde signifikanta prediktorer gällande undersökningsdeltagarnas intentioner. Därtill påvisades samband mellan föräldrars utbildningsnivå och deltagarnas intentioner samt subjektiva norm. Författaren menar att studier likt denna ger ett värdefullt bidrag till det viktiga arbetet med att förverkliga den svenska skolans likvärdighetsmål.

A dislocation based theory for the deformation hardening behavior of DP steels : Impact of martensite content and ferrite grain size

A dislocation model, accurately describing the uniaxial plastic stress-strain behavior of dual phase (DP) steels, is proposed and the impact of martensite content and ferrite grain size in four commercially produced DP steels is analyzed. It is assumed that the plastic deformation process is localized to the ferrite. This is taken into account by introducing a non-homogeneity parameter, f(e), that specifies the volume fraction of ferrite taking active part in the plastic deformation process. It is found that the larger the martensite content the smaller the initial volume fraction of active ferrite which yields a higher initial deformation hardening rate. This explains the high energy absorbing capacity of DP steels with high volume fractions of martensite. Further, the effect of ferrite grain size strengthening in DP steels is important. The flow stress grain size sensitivity for DP steels is observed to be 7 times larger than that for single phase ferrite.