Concentrated Winding Multiphase Permanent Magnet Machine Design and Electromagnetic Properties – Case Axial Flux Machine

Concentrated winding permanent magnet machines and their electromagnetic properties are studied in this doctoral thesis. The thesis includes a number of main tasks related to the application of permanent magnets in concentrated winding open slot machines. Suitable analytical methods are required for the first design calculations of a new machine. Concentrated winding machines differ from conventional integral slot winding machines in such a way that adapted analytical calculation methods are needed. A simple analytical model for calculating the concentrated winding axial flux machines is provided. The next three main design tasks are discussed in more detail in the thesis. The magnetic length of the rotor surface magnet machines is studied, and it is shown that the traditional methods have to be modified also in this respect. An important topic in this study has been to evaluate and minimize the rotor permanent magnet Joule losses by using segmented magnets in the calculations and experiments. Determination of the magnetizing and leakage inductances for a concentrated winding machine and the torque production capability of concentrated winding machines with different pole pair numbers are studied, and the results are compared with the corresponding properties of integral slot winding machines. The thesis introduces a new practical permanent magnet motor type for industrial use. The special features of the machine are based on the option of using concentrated winding open slot constructions of permanent magnet synchronous machines in the normal speed ranges of industrial motors, for instance up to 3000 min-1, without excessive rotor losses. By applying the analytical equations and methods introduced in the thesis, a 37 kW 2400 min-1 12-slot 10-pole axial flux machine with rotor-surfacemounted magnets is designed. The performance of the designed motor is determined by experimental measurements and finite element calculations.

Métodos de amostragem e análise para compostos reduzidos de enxofre atmosférico

This work presents a review of sampling and analytical methods that can be applied to atmospheric traces of reduced sulphur compounds (RSC) in the atmosphere. Sampling methodology involving discontinuous methods with preconcentration is mostly used. For the most part, adsorption on solids and cryogenic capture are applied as a procedure. The analysis of these compounds has been done mainly by gas chromatography with FPD, fluorescence and spectrophotometry. Advantages and disadvantages of the methodologies are also mentioned in this paper, aiming to guide the reader towards the most appropriate choice of a sampling and analytical method for RSCs.

Contaminantes voláteis provenientes de embalagens plásticas: desenvolvimento e validação de métodos analíticos

Plastic packaging materials intended for use in food packaging is an area of great interest from the scientific and economic point of view due to the irreversible internationalization and globalization process of food products. Nevertheless, a debate related to food safety aspects has emerged within the scientific community. Therefore, the development of analytical methods that allow identifying and quantifying chemical substances of toxicological potential in the packaging is considered essential. This article focuses on the main analytical methods, including validation parameters, as well as extraction and quantification techniques for determination of volatile organic compounds from food packaging materials.

A espectrometria atômica e a determinação de elementos metálicos em material polimérico

Polymeric materials are widely used in the chemical industry and are part of our daily lives. Inorganic species may be added to them as additives, anti-oxidizing agents, stabilizers, plasticizers, colorants and catalysts and may be present in a wide range of concentrations. Their determination demands the development of analytical methods considering different kinds of polymeric materials, their composition and the final use of the material. Although many different analytical techniques may be used, this review emphasizes those based on atomic absorption and emission spectrometry. Solid sampling techniques and digestion methods are described and discussed and compared considering published results.

El análisis prolongacional y el análisis paradigmático en el aula : dos propuestas metodológicas para el Grado Profesional

En este trabajo he realizado una contextualización y profundización en dos métodos de análisis musicales de cara a dotar a los y las estudiantes de Grado Profesional de unas herramientas metodológicas sólidas, así como un conocimiento crítico del método para poder problematizar la obra y tener un objetivo a la hora de aplicarlo. Lo realizo de cara a la falta de este tipo de propuestas sistemáticas en la asignatura de Análisis Musical, y para ejemplificar cómo los enseñaría he elaborado una hipotética Unidad Didáctica para cada uno.

Resíduos de agrotóxicos em alimentos: uma preocupação ambiental global - Um enfoque às maçãs

This paper describes the use of pesticides in agriculture. Research has shown that significant quantities of pesticide residues have been found in many types of foods. Thus, an overview is given of pesticide residue determinations in fruits and vegetables, with special attention to apples. The toxicity and the adverse effects possibly caused by the exposure of these compounds are alerting the scientific community to develop studies about the validation of analytical methods for multiresidue pesticide determination in these samples. This review shows that pesticide-residue determination in apples is becoming a very important and challenging issue.

Biodiesel: parâmetros de qualidade e métodos analíticos

The establishment of quality standards for biodiesel was a key step to win the confidence of the market and the automotive industry, thus ensuring the success of the new fuel. In this review are presented standard methods and other analytical methods suggested for analysis of biodiesel. The methods of analysis were divided into groups according to information that may be provided on the contaminants from the raw material of the production process, the molecular structures of biodiesel and its degradation during storage.

Contaminação de produtos de higiene e cosméticos por n-nitrosaminas

N-nitrosamines are carcinogenic compounds that have been found during the last three decades in a variety of consumer products, including cosmetic and personal care products, and their raw materials. These compounds are formed from amine precursors and nitrosating agents present in the formulations. This paper reviews the formation and occurrence of N-nitrosamines in cosmetic products, as well as presents considerations about analytical, toxicological and regulatory aspects.

Validação de métodos cromatográficos de análise: um experimento de fácil aplicação utilizando cromatografia líquida de alta eficiência (CLAE) e os princípios da "Química Verde" na determinação de metilxantinas em bebidas

The validation of analytical methods is an important step in quality control. The main objective of this study is to propose an HPLC experiment to verify the parameters of validation of chromatographic methods, based on green chemistry principles, which can be used in experimental courses of chemistry and related areas.

Otimização e validação de métodos analíticos para determinação de BTEX em água utilizando extração por headspace e microextração em fase sólida

Three analytical methods for the determination of BTEX in water were optimized and validated. With the best method the analytes were extracted of 10 mL of sample with 2.50 g of NaCl in headspace vial of 20 mL by HS and SPME to 40 ºC for 30 min for adsorption and to 250 ºC for 4 min for desorption and were analyzed by GC-MS. The recovery was between 97.9% and 104.3%, and the limit of detection was 2.4 ng L-1 for o-xylene. This method was using to analyze BTEX in water supply and surface water in Ouro Preto city. No sample had concentrations of BTEX above the legislation.

Losartan potassium dissolution test for drug release evaluation in pharmaceutical capsules using HPLC and UV spectrophotometry

This work describes the development and validation of a dissolution test for 50 mg losartan potassium capsules using HPLC and UV spectrophotometry. A 2(4) full factorial design was carried out to optimize dissolution conditions and potassium phosphate buffer, pH 6.8 as dissolution medium, basket as apparatus at the stirring speed of 50 rpm and time of 30 min were considered adequate. Both dissolution procedure and analytical methods were validated and a statistical analysis showed that there are no significant differences between HPLC and spectrophotometry. Since there is no official monograph, this dissolution test could be applied for quality control routine.

Desenvolvimento de métodos analíticos para determinação de agrotóxicos em sedimentos por cromatografia gasosa monodimensional e bidimensional abrangente com micro detector de captura de elétrons

The development of analytical methods for determination of eight pesticides of different chemical classes (trichlorfon, propanil, fipronil, propiconazole, trifloxystrobin, permethrin, difenoconazole and azoxystrobin) in sediments with gas chromatography-micro-electron capture detector (GC/µECD) and comprehensive two-dimensional gas chromatography with micro-electron capture detector (GCxGC/µECD) is described. These methods were applied to real sediment samples, and the best results were obtained using a 5% diphenyl-methylpolysiloxane column for 1D-GC. For GCxGC the same column was employed in the first dimension and a 50%-phenyl-methylpolysiloxane stationary phase was placed in the second dimension. Due to the superior peak capacity and selectivity of GCxGC, interfering matrix peaks were separated from analytes, showing a better performance of GCxGC.

Produção científica da área da Química no desenvolvimento da oceanografia no Brasil

This paper analyses the scientific contribution of chemists and of the Brazilian Chemical Society (SBQ) and its publications to the development of Oceanography in Brazil, as well as major drivers of this participation. A total of 528 articles were analyzed. Most articles (72%) originated in research groups not associated with graduate programs in oceanography. Nearly 50% dealt with the contamination of the marine environment, followed by chemical process studies (32%) and analytical methods development (15%). SBQ journals contributed with 78 articles (14.7% of the total), and rank 1st (QN) and 2nd (JBCS) among scientific journals publishing the analyzed articles.

Um método verde, rápido e simples para determinar o valor energético de farinhas e cereais matinais

The Energy Value (EV) corresponds to the sum of the energetic contributions from food macronutrients (proteins, carbohydrates and fats) and is required on the labels of pre-packaged foods. The determinations of these parameters are based on distinct analytical procedures, each one being time-consuming, laborious and producing residues. This work presents multivariate models to determine the EV contents of industrialized foods for human consumption by using X-ray fluorescence spectra of samples with known parameters, determined through conventional methods. The proposed method is an alternative to conventional analytical methods and does not require any reagent, given the demands of the "green chemistry".

Desenvolvimento de método analítico para quantificação do efavirenz por espectrofotometria no UV-Vis

An UV-Vis spectrophotometry analytical method for quantifying Efavirenz was developed and validated as an alternative to replace the HPLC current method. The report method presents sample concentration of 10 μg mL-1, dissolved in a solution ethanol:water (60:40, v/v), economic and technically adequate for the purpose adopted. The results and the statistical treated proved that the method being considered an precise and accurate analytical low cost alternative for laboratory routine. The adaptability of this method in product and other analytical methods development has been challenged by mathematical calculation of drug extinction coefficient in water and methanol and practical experiments, showing interesting results.