Resumo Este trabalho objetivou avaliar a estabilidade térmica e a foto-estabilidade do potencial antioxidante (PA) da biomassa da Spirulina platensis. A estabilidade térmica foi avaliada a 25ºC, 40ºC e 50ºC por 60 dias. A foto-estabilidade foi avaliada usando luz UV (15 W, λ = 265 nm) e fluorescente (20 W, 0.16 A, fator de potência FP > 0.5, 50/60 Hz, 60 lm/w, 1200 lm) por 90 dias em cápsulas, vidro e placas de Petri. O PA da biomassa nessas condições foi determinado em intervalos de tempo (a cada 7 e 30 dias nos estudos de estabilidade térmica e foto-estabilidade, respectivamente), usando a indução da oxidação de um sistema lipídico por calor e aeração. Neste sistema lipídico, a biomassa submetida à degradação foi usada como antioxidante. A cinética da reação foi determinada pelo método de Arrhenius. A degradação térmica seguiu uma cinética de zero ordem, enquanto que a fotodegradação seguiu uma cinética de primeira ordem. O PA diminuiu 50% depois de 50 dias a 25°C. A 40°C e 50°C, o PA diminuiu mais de 50% depois de 35 e 21 dias de exposição, respectivamente. A diminuição do PA da Spirulina foi mais sensível à luz UV e fluorescente. Depois de 30 dias de exposição, o PA diminuiu mais de 50% em todas as condições de armazenamento testadas. O potencial antioxidante da Spirulina platensis é facilmente diminuído quando a biomassa é exposta ao calor e a luz, indicando a necessidade de cuidados durante seu armazenamento.

Abstract This work aimed to evaluate the thermal and photo stability of the antioxidant potential (AP) of the Spirulina platensis biomass. Thermal stability was established at 25ºC, 40ºC and 50ºC for 60 days, in the dark, protected from light. Photo stability was evaluated using UV (15 W, λ = 265 nm) and fluorescent (20 W, 0.16 A, power factor FP > 0.5, 50/60 Hz, 60 lm/w, 1200 lm) light for 90 days in capsules, glass and Petri dishes, at room temperature. The AP of the biomass in these conditions was determined at intervals (every 7 and 30 days in the studies of thermal and photo stability, respectively) using the induction of the oxidation of a lipid system by heat and aeration. In this lipid system, the biomass submitted to degradation was used as an antioxidant. The kinetics of the reaction was determined by the Arrhenius method. Thermal degradation was found to follow zero order kinetics, whereas photo degradation followed first order kinetics. The AP decreased 50% after 50 days at 25°C. At 40°C and 50°C, the AP decreased more than 50% after 35 and 21 days of exposition, respectively. The decrease of the AP of Spirulina was more sensible to UV and fluorescence light. After 30 days of exposition, the AP decreased more than 50% in all storage conditions tested. The antioxidant potential of Spirulina platensis is easily degraded when the biomass is exposed to heat and light, indicating the need for care to be taken in its storage.

Abstract Cultivation conditions and the process considerably influence the composition of microalgae. The objective of this study was to use CO2 as a carbon source in semi-continuous cultivation of Spirulina sp. LEB 18 and Chlorella fusca LEB 111 and to evaluate the influence of the renewal rate on the biomass composition and production of these microalgae. Spirulina sp. LEB 18 and Chlorella fusca LEB 111 were cultivated with 10% (v/v) CO2. The blend concentration was 1.6 g L-1, and 20 and 40% (v/v) renewal rates were studied. Spirulina sp. LEB 18 presented the best kinetic results and the maximum biomass concentration and biopolymer yield when grown with CO2 as the carbon source. Under the same conditions (10% (v/v) CO2), the microalgae Spirulina sp. LEB 18 and Chlorella fusca LEB 111 exhibited maximum levels of protein, carbohydrates and lipids.

The carbon source is the most expensive nutrient for Spirulina production; effluents from anaerobic digestion contain this nutrient in the form of HCO3-. The aim of this study was to assess the growth kinetics, composition and fatty acid profile of Spirulina sp. LEB-18 grown in standard Zarrouk medium (NaHCO3 16.8 g L-1) and in Zarrouk medium replaced with 20% (v/v) effluent with reduced concentrations of NaHCO3 (5.3 and 2.8 g L-1). The use of effluent and lower concentrations of HCO3 was found to be an alternative to reduce the costs of Spirulina production, because there were no significant differences in growth parameters (µmax 0.324 - 0.354 d-1; Pmax 0.280 - 0.297 g L-1 d-1), in the different culture medium used. Lipids ranged between 4.9 and 5.0%; the media with effluent had higher levels of linoleic acid compared to the standard medium.

No sudeste de Santa Catarina existem inúmeras minas de exploração de argilas destinadas à indústria cerâmica da região. Para o conhecimento desta matéria prima foi realizada a caracterização em detalhe de uma frente de lavra em atividade. A exploração é realizada em terrenos sedimentares da Formação Rio do Rasto (Permiano Superior) na Bacia do Paraná que afloram como morros testemunho. Foram coletadas quatorze amostras representativas dos níveis desta mina composta de argilitos com intercalação de siltitos de pequena espessura. As amostras foram analisadas por difratometria de raios X pelo método do pó na rocha total e na fração < 4 µm. A composição química foi determinada por fluorescência de raios X. Foram realizadas observações ao microscópio eletrônico de varredura (elétrons secundários) de fragmentos das amostras e microanálises por microssonda eletrônica de lâminas delgadas. Os resultados mostraram uma grande variação vertical da mineralogia, tendo sido identificados três níveis diferentes. Até 2,00 m há predomínio de esmectita. Entre 2,00 m e 5,50 m a esmectita é o principal argilomineral, mas com quantidade significativa de ilita/mica, e acima de 5,50 m há grande aumento do feldspato potássico e mica detrítica. Estudos de detalhe por difratometria de raios X (determinação do parâmetro b) e microanálises WDS por microssonda eletrônica permitiram identificar como montmorilonita a espécie argilomineral do grupo das esmectitas.

In the southeastern part of Santa Catarina state, Brazil, many mines of clays used as raw material for the ceramic industry are found. A detail study of this material was developed in a mine in activity. The exploitation of clays is held in sedimentary rocks of Rio do Rasto Formation (Upper Permian) in the Paraná Basin. The outcrops are in hills testimonies. Fourteen samples were collected and represent the levels of this mine which consisted of argillites with intercalation of slim siltite layer. These samples were analyzed by X-ray diffraction using the powder method and in the fraction < 4 µm. The chemical composition was determined by X-ray fluorescence spectrometer. Petrographic observations in thin section were also performed. Scanning electron microscope images was obtained in samples fragments by secondary electron method. Electron microprobe microanalysis was performed in one thin section. The results showed large vertical variation in the mineralogy and it has been identified three different levels. Up to 2.00 m there is a predominance of smectite. Between 5.50 m 2.00 m the smectite is the main clay mineral, but with significant amounts of illite/mica and above 5.50 m occurs large increase in K-feldspar and detrital mica. Studies in detail by X-ray diffraction (determination of the b-parameter) and microanalysis by wavelength dispersive X-ray spectroscopy have identified montmorillonite clay mineral as the smectite mineral specie.

Neste trabalho, apresenta-se o estudo experimental em escala laboratorial e industrial da incorporação de resíduo do tratamento de Drenagem Ácida de Mina (DAM) na formulação de massa de cerâmica vermelha, com substituição parcial das argilas. Foram realizados algumas análises e ensaios nas amostras dos blocos cerâmicos: análise dilatométrica a verde, absorção de água, resistência à compressão, eflorescência de sais solúveis e emissões atmosféricas (MP e SOx). Os resultados das análises nos corpos de prova ensaiados indicam aumento de resistência a compressão. Os ensaios de eflorescência de sais solúveis indicam maior intensidade de cristalização de sais solúveis na superfície dos corpos de prova e blocos cerâmicos à medida que se aumenta o percentual de resíduo. As análises realizadas nos blocos cerâmicos ensaiados em escala industrial, recomendam uma proporção de até 2,5% de resíduo na massa cerâmica.

An experimental laboratory and industry scale study of the incorporation of residue from Acid Drainage Mine (ADM) in the ceramics mass, with partial substitution of clays, is presented. Some analyses and assays of the ceramic blocks were been carried out: dilatometry, water absorption, compressive strength, efflorescence and emissions (MP and SOx). The results show an increase of compressive strength. The efflorescence assays indicate greater intensity of crystallization of soluble salts in the surface of the ceramic blocks for increasing residue content. The analyses in the ceramic blocks in industrial scale recommend a ratio of up to 2.5% of waste in bulk ceramics.

The cultivation of photosynthetic microorganisms such as the cyanobacterium Spirulina platensis has been studied by researchers in many countries because these organisms can produce products with industrial potential. We studied the specific growth rate (µx, day-1) and productivity (Px, in mg/L/day of Spirulina platensis biomass, dry weight basis) of two S. platensis strains (LEB-52 and Paracas) growing in aerated semicontinuous culture in two-liter Erlenmeyer flasks for 90 days (2160 h) at 30°C under 2500 lux of illumination in a 12 h photoperiod. Independent of the S. platensis strain used we found that low biomass concentrations (0.50 g/L) and high renewal rates (50% v/v) resulted in a high specific growth rate (µx = 0.111 day-1) and high productivity (Px = 42.3 mg/L/day). These values are two to four times higher than those obtained in simple batch cultivation and indicate that the semicontinuous cultivation of S. platensis is viable.

Some case reports have been published in the literature about thrombosis associated with several risk factors, specially in hypercoagulability state. Nevertheless, we have not found any description of a case like this of hyperthrombophilia status without thrombotic events. We present a 75 years old woman who was assessed for thrombophilia state on occasion of a deep venous thrombosis which affected to her daughter. Many thrombosis risk factors were detected (13 altogether), both inherited and acquired, arterial and venous, that surprisingly, have not led to any thrombosis event. Its description led us to highlight the risk factors of this patient and to open questions about the present knowledge on etiology and etiopathogenesis of thrombotic phenomena.

Se han publicado diferentes casos clínicos de pacientes afectos de trombosis con asociación de factores de riesgo, especialmente estados de hipercoagulabilidad. Sin embargo, no hemos encontrado en la literatura un caso como el que presentamos: una mujer de 75 años, evaluada para trombofilia a raíz de un episodio de trombosis venosa profunda que afectó a su hija, a la que se le ha detectado una acumulación factores de riesgo (13 en total), tanto congénitos como adquiridos, arteriales como venosos que, sorprendentemente, no ha abocado a evento trombótico alguno. Su exposición nos permite incidir sobre los factores de riesgo de la paciente y abrir interrogantes sobre el conocimiento actual de la etiología y etiopatogenia de los fenómenos trombóticos.

Fe10Ag90 granular alloys have been fabricated, using a sol-gel method, for a range of nitric acid concentrations in the start solution. The samples have been characterized by X-ray diffraction and magnetization measurements. The average Fe particle sizes derived from X-ray diffraction are in the range 24-29 nm, indicating a large variation. The coercivity obtained from the hysteresis curve is two orders of magnitude larger that of pure iron in all the samples. Moreover, the hysteresis curves do not saturate, even in fields of up to 1 T. These observations indicate that the samples contain both superparamagnetic and blocked particles. A comparison between the coercive field and the average particle diameter, determined by the Sherrer's formula, is displayed in all acid concentrations.

Autoimmune hepatitis (AIH) is a hepatocellular inflammation that is characterised by a wide range of histolopatholgic (periportal interface hepatitis with plasma cell infiltration and piecemeal necrosis), biochemical (hypertransaminasemia, hypergammaglobulinaemia) and autoimmune (several autoantibodies presence) features. This relatively rare disorder frequently affects middle-aged women. There is no pathognomonic marker for AIH diagnosis, therefore it requires a careful rule out of other causes of liver disease together with the detection of a suggestive pattern of clinical and laboratory abnormalities. Scoring system for AIH diagnosis proposed by International Autoimmune Hepatitis Group has been used as a tool in clinical practice but is not sufficiently exclusive in terms of defining prognosis or treatment. AIH has been classified in two subtypes according to autoantibodies detected: 1 and 2, but this classification results in poor clinical implications. Previously known as subtype 3 is at the present included in subtype 1 because no clinical significant differences has been found between them. Aetiology, and molecular mechanisms still remain to be elucitaded in this disease, although viruses, drugs and molecular mimicry act presumably as a trigger in genetically predisposed patients (associated with HLA-DR3 and DR4 haplotypes). On the other hand, immunosuppresive therapy (corticosteroid or azathioprine) generally offers favourable response. Our aim is to review this disease from different points of view, considering: clinical, histopathological, etiologic, genetic, biochemical, autoimmune, treatment and prognosis features.

La hepatitis autoinmune es una inflamación hepatocelular que se presenta cuando el sistema inmunológico actúa frente a los hepatocitos y que se caracteriza por hallazgos histológicos (hepatitis de interfase con afectación periportal, infiltración de células plasmáticas y necrosis en sacabocados), bioquímicos (hipertransaminasemia e hipergammaglobulinemia) y autoinmunes (presencia de ciertos autoanticuerpos). Este trastorno es relativamente poco frecuente y suele afectar a mujeres de mediana edad. Al no existir un marcador patognomónico para su diagnóstico se requiere una exclusión cuidadosa de otras causas de enfermedad hepática conjuntamente con un patrón clínico y analítico compatible. El criterio de puntuación propuesto por el Grupo Internacional de la Hepatitis Autoinmune para su diagnóstico no es suficientemente específico como para definir la prognosis y el tratamiento. La hepatitis autoinmune se clasifica, según los autoanticuerpos presentes, en subtipos 1 y 2, aunque esta clasificación no muestra repercusiones clínicas importantes. El anteriormente conocido como subtipo 3 no difiere clinicamente del 1 en forma significativa y por tanto debe incluirse dentro de este último grupo. Todavía permanecen por dilucidar la etiología y las bases moleculares de esta enfermedad, originada probablemente por la interacción de diversos factores como la predisposición genética (haplotipos HLA-DR3 y DR4), pérdida de tolerancia inmunológica, formación de neoantígenos por factores desencadenantes como virus o fármacos, y por mimetismo molecular. La terapia inmunosupresora (corticosteroides, azatioprina) ofrece excelentes resultados. Nuestro objetivo es revisar esta enfermedad bajo diferentes puntos de vista, considerando: los aspectos clínicos, histopatológicos, etiológicos, genéticos, bioquímicos, autoinmunes, de tratamiento y pronóstico.

Cystinuria is an autosomal recessive disorder with an estimated incidence of 1 case in 7000 live births, that results in elevated urinary excretion of cystine and dibasic aminoacids: ornithine, lysine and arginine. Discussed by Sir Archibald Edward Garrod, in 1908, as one of the four first known inborn errors of metabolism, it is characterized by a defect in transport of cystine and dibasic aminoacids, that affects their reabsortion in both renal tubule and gastrointestinal tract. To date, according to the recent molecular findings, two genes have been identified as responsible for this disease: SLC3A1 and SLC7A9. A more accurate pheno/genotyping identification of cystinuric patients will allow to improve prophilaxis and therapy for this illness. Cystinuria only causes recurrent urolithiasis (about 1-2 % of renal calculi in adults) and its associated complications as clinical feature because of poor cystine solubility at low pH. An accurate control over prohylaxis (based on high water intake and potassium citrate treatment, on first line, and tiol-derivatives treatment, on second line) must be taken in patients -like homozygous type I- with high lithiasis risk. However, approximately one half of patients under prophylaxis control will develop recurrent lithiasis; in this case, only urology or surgical approaches would be possible. Updated knowledge about biochemical, genetic, clinical, diagnosis, prevention, treatment and prognosis aspects of this, relatively unusual, disease has been reviewed in this article.

La cistinuria es una enfermedad autosómica recesiva, con una incidencia estimada de un caso por cada 7000 nacidos vivos, que ocasiona una elevada excreción urinaria de cistina, lisina, arginina, y ornitina. Descrito ya en 1908, por sir Archibald Edward Garrod, como uno de los cuatro primeros errores del metabolismo conocidos, se caracteriza por un defecto en el transporte de cistina y de los aminoácidos dibásicos que afecta a su reabsorción en el túbulo renal y tracto gastrointestinal. Hasta la fecha, según hallazgos moleculares recientes, se han identificado dos genes como responsables de esta enfermedad: SLC3A1 y SLC7A9. Una correcta identificación fenotípica y/o genotípica de los pacientes cistinúricos permitirá una mejor profilaxis y terapia para esta patología. La cistinuria ocasiona urolitiasis recurrente (aproximadamente el 1-2 % de los cálculos renales del adulto) debida a una deficiente solubilidad de la cistina a pH bajo. La calcinogénesis y sus complicaciones asociadas son las únicas manifestaciones clínicas de esta enfermedad. Las medidas profilácticas, basadas en una alta ingesta hídrica y la alcalinización de la orina con citrato potásico, en primera línea; y la utilización del arsenal farmacológico de derivados tiólicos, en segunda línea, se deberá extremar en aquellos pacientes (como los homocigotos tipo I) de alto riesgo litógeno. No obstante, para aproximadamente un 50 % de los pacientes sometidos a control preventivo y que, a pesar de ello, desarrollarán litiasis recidivante, los procedimientos urológicos y quirúrgicos serán la única alternativa posible. En este artículo revisamos y actualizamos el conocimiento sobre los aspectos bioquímicos, genéticos, clínicos, diagnósticos, de prevención, tratamiento y pronósticos de esta, relativamente rara, enfermedad.

The complex mobility of electrons in 3C - and 6H-SiC subjected to intense high frequency electric fields is calculated taking into account effects of band nonparabolicity. The electric field, given by a dc component plus an ac component in the frequency range 0.1-100 THz, is applied along the [0001] ([111]) direction in the hexagonal (cubic) polytype. The real electron mobility presents a characteristic maximum peaking around 6-8 THz, while the imaginary electron mobility is structured, with characteristic minimum and maximum around 2-3 THz and 20{30 THz, respectively. These mobilities are seen to smooth down for higher temperatures in both polytypes.

A study of the subpicosecond high-field electron transport transient in 3C- and 6H-SiC polytypes at high lattice temperatures is performed. Electric field intensities up to 1000 kV/cm and lattice temperatures of 300, 673, and 1073 K are considered. It is shown that the transient regime behavior depends on the electric field intensity as well as on the lattice temperature, but it is always shorter or of the order of 0.3 ps. For the lowest lattice temperature, an electron velocity overshoot can always occur when the electric field intensity is higher than 300 kV/cm, but it decreases and can even disappear when the lattice temperature is raised.