EVIDENCE OF ELECTRICAL CONDUCTIVITY IN LI(4-2X)NIXTI2O6 DOUBLE PEROVSKITE

The polycrystalline nature of Li Ni Ti O (where X = 0, 0.25, 0.50, 0.75) (LNT) were synthesized by sol-gel method and (4-2x) x 2 6 microwave processing method. The powder X-ray diffraction technique confirms the monoclinic crystal structure and C2/c space group. The high resolution scanning electron microscope studies revealed particle size 30 [1]. The temperature scan of conductivity demonstrated the existence of thermally generated charge carriers. The conduction mechanism in LNT compositions is discussed and found to be band type conduction

Kinetics and variation of volatile components of Atractylodis Macrocephalae Rhizoma during hot-air drying / 中国中药杂志

The present study explored the kinetics and variation of volatile components of Atractylodis Macrocephalae Rhizoma during the hot-air drying process to obtain the optimal process parameters under multiple goals such as drying efficiency and drying quality. The dry basis moisture content and drying rate curves along with the change of drying time of Atractylodis Macrocephalae Rhizoma were investigated at five levels of drying air temperatures(30, 40, 50, 60, and 70 ℃). The relationship between moisture ratio and time in the drying process of Atractylodis Macrocephalae Rhizoma was fitted and verified by Midilli model, Page model, Overhults model, Modified Page model, Logaritmic model, Two terms Exponential model, and Newton model. Meanwhile, the effective diffusion coefficient of moisture(D_(eff)) and activation energy(E_a) in Atractylodis Macrocephalae Rhizoma were calculated under different drying air temperatures. GC-MS was used to determine the volatile components and content changes of the fresh Atractylodis Macrocephalae Rhizoma and dried products at different temperatures. The dry basis moisture content and drying rate of Atractylodis Macrocephalae Rhizoma were closely related to the temperature of the drying medium, and the moisture of the Atractylodis Macrocephalae Rhizoma decreased with the prolonged drying time. As revealed by the drying rate curve, the drying rate increased with the increase in hot air temperature, and the migration of moisture was accelerated. The comparison of the correlation coefficient(R~2), chi-square(χ~2), and root mean standard error(RMSE) of each model indicated that the parameter average of the Midilli model had the highest degree of fit, with R~2=0.999 2, χ~2=8.78×10~(-5), and RMSE=8.20×10~(-3). Besides, the D_(eff) at 30-70 ℃ was in the range of 1.04×10~(-9)-6.28×10~(-9) m~2·s~(-1), and E_a was 37.47 kJ·mol~(-1). The volatile components of fresh Atractylodis Macrocephalae Rhizoma and dried products at different temperatures were determined by GC-MS, and 18, 18, 18, 17, 17, and 18 compounds were identified respectively, which accounted for more than 84.76% of the volatile components. In conclusion, the hot-air drying of Atractylodis Macrocephalae Rhizoma can be model-fitted and verified and the variation law of the moisture and volatile components of Atractylodis Macrocephalae Rhizoma with temperature is obtained. This study is expected to provide new ideas for exploring the drying characteristics and quality of aromatic Chinese medicine.

Determination of the activity and kinetic parameters of polyphenol oxidase enzyme in crude extracts of some Jordanian plants

The activity and kinetic parameters of the enzyme polyphenol oxidase (PPO) in crude extracts of the fruits ofParadise apple (Pyrus malus L.), cucumber (Cucumis sativus L.), squash (Cucurbita pepo L.), pomegranaterind and seeds (Punica granatum L.), and the leaf of cactus (Opuntia ficus-indica (L.) were investigated. Thehighest browning intensity was found in P. apple, followed by pomegranate seeds and cucumber fruits. Theoptimum activity of the enzyme was shown at pH 7.0 for P. apple and cucurbita, but it was found at pH 6.0 forthe rind and seeds of the pomegranate. The PPO of cactus leaf and cucumber fruits showed two peaks at pH 4.0and 7.0. On the other hand, the optimal temperature found for PPO activity in these plants was around 40°C.A strong correlation with value (R) = 0.9485 between the browning intensity and PPO activity in all studiedsamples was obtained.

Study on formation regularity and kinetics of advanced glycation end-products during processing of boiled Cervi Cornu Pantotrichum / 中草药

Objective: To study the formation regularity and kinetic parameters of advanced glycation end-products during the processing of boiled Cervi Cornu Pantotrichum (CCP). Methods: UV-visible spectrophotometry and UPLC-MS/MS method were used to determine the change of browning index and content of typical advanced glycation end-products, Nε-(carboxymethyl) lysine and Nε-(carboxyethyl) lysine, of the processing system of simulated boiled CCP. The formation regularity and kinetic parameters of advanced glycation end-products during the processing of boiled CCP were discussed by constructing glucose and lysine to simulate the Maillard reaction system of CCP processing. Results: The activation energy of browning reaction, Nε-(carboxymethyl) lysine and Nε-(carboxyethyl) lysine reaction during processing of boiled CCP were 5.07, 40.44 and 78.47 kJ/mol, respectively, and all of them were zero-order kinetics. The activation energies of the above reactions in the baking process were 6.72, 89.34 and 164.77 kJ/mol, respectively, and all of them were zero-order kinetics. Compared to the formation of Nε-(carboxymethyl) lysine, the formation of Nε-(carboxyethyl) lysine required higher activation energy and was more difficult to occur. Conclusion: The temperature changed in the baking process has a significantly higher effect on the kinetic parameters of the advanced glycation end-products than in the boiling process. Long-term higher baking temperature resulted in more advanced glycation end-products produced in the boiled CCP. This study provides a solid theoretical basis for the blocking and inhibition strategies of advanced glycation end-products in the processing of CCP, which is also a great significance for the production of green safety CCP and strengthening the safety of traditional Chinese medicine.

Drying characteristics of Chaenomeles sinensis with different drying methods based on Dincer model / 中草药

Objective: Based on Dincer model, the drying characteristic of Chaenomeles sinensis under different drying condition was investigated in order to provide theoretical foundation for applying Dincer model to analyze heat and mass transfer during Chinese herbs drying process and select suitable drying technology and process. Methods: C. sinensis slice of thickness 12 mm was dried by the three different drying methods, namely air impingement drying, medium and short infrared waved drying and pulsed vacuum drying. Also, 9, 12 and 15 mm C. sinensis slices were dried under air impingement drying method. The drying characteristic, color value, rehydration ration, vitamin C (VC), general flavone, and microstructure were studied. Results: At the same drying temperature, the drying rate sorted in order of size was air impingement drying, medium and short infrared waved drying and pulsed vacuum drying and the drying activation energy was 43.10, 36.95 and 20.37 kJ/mol in corresponding. Decreasing slice thickness enhanced drying rate. The Weibull distribution model simulation result showed that the scale parameter α ranged from 47.85 to 324.51. Smaller α value meant short drying time. The shape parameter β was between 1.218 7 and 1.290 8 under air impingement drying as well as medium and short infrared waved drying method, which showed that drying was falling rate process controlled by internal moisture diffusion. However, the shape parameter β was between 1.218 7 and 1.290 8 under pulsed vacuum drying method, which illustrated that drying was controlled both by internal moisture diffusion and surface moisture evaporation. The calculated moisture diffusion coefficient was ranged from (1.66 × 10-8) to (1.13 × 10-7) m2/s and decreased as α increased. The Dincer model simulation result showed that the lag factor (G) was range from 1.135 6 to 1.337 6, which declared that there was a short raising rate drying period during the initial drying process. Heat transfer Biot number (Bi) value was between 1.171 4 and 136.041 2 and decreased as drying temperature increased. Effective moisture diffusion (Deff) value calculated by Diner model was range from (3.26 × 10-9) to (6.33 × 10-8) m2/s. At the same drying temperature, (Deff) value was larger than (D*), but smaller than (Dcal). Mass transfer (k) was ranged from (9.02 × 10-6) to (8.82 × 10-5) m/s and increased as drying temperature increased. Air impingement drying method was suitable for C. sinensis slice drying, and drying temperature of 60 ℃ and thickness of 12 mm was the most optimum drying process. Under above drying circumstance, the drying time, brightness L*, color difference value ΔE, VC, general flavone and rehydration ratio were 5 h, 62.80 ± 1.70, 19.62 ± 2.60, (1.107 8 ± 0.005 0) mg/g, (36.74 ± 0.60) mg/g and 7.11 ± 0.24, respectively. Conclusion: Such investigation result can provide theoretical foundation for applying Dincer model to describe heat and mass transfer characteristics during Chinese herbs drying and filtrating suitable C. sinensis slice drying method and process.

Caracterización y estabilidad de un extracto rico en antocianinas a partir de corteza de gulupa / Characterization and stability of an extract rich in anthocyanins from passion purple fruit peel / Caracterização e estabilidade de um extrato rico em antocianinas de cortez de fruta roxa da paixão

Resumen La gulupa es una fruta originaria de la región amazónica, cuyo epicarpio es un subproducto con alto potencial en antioxidantes como las antocianinas. Por lo anterior, los objetivos de este estudio fueron realizar una extracción por solvente, a partir del epicarpio, para obtener un extracto rico en antocianinas; caracterizar su capacidad antioxidante y realizar la cinética de degradación de antocianinas monoméricas durante el almacenamiento a tres temperaturas (-14 ± 2 °C, 5 ± 1 °C y 21 ± 0,7 °C). En consecuencia, se obtuvo un extracto con un contenido de antocianinas de 165 ±9 mg cianidina-3-O-glucosido/L. La capacidad antioxidante fue de 464 ± 19 y 366 ± 7 μmol Trolox/100 g de extracto, según los ensayos FRAP y DPPH respectivamente, y un contenido de vitamina C de 2,07 ± 0,04 mg ácido ascórbico/100 g de extracto. La cinética de degradación se definió por el orden uno con las siguientes constantes: 2, 1·10-3, 8, 6·10-3 y 2,7·10-2 días-1 para -14 ± 2 °C, 5 ± 1 °C y 21 ± 0,7 °C respectivamente, generando una energía de activación de 46, 0·103 J/mo'l. Por consiguiente, se concluyó que es posible obtener, a partir del epicarpio de gulupa, extractos ricos en compuestos de alto valor como las antocianinas, los cuales son afectados por la temperatura de almacenamiento, siendo este un factor para considerar durante su aplicación en matrices alimentarias.

Abstract Purple passion fruit is a fruit from the Amazon region whose epicarp is a by-product with high potential as a source of anthocyanins. The objective of this investigation was to do a solvent extraction from the epicarp to obtain an extract rich in anthocyanins, and then, to characterize its antioxidant capacity, and evaluate the anthocyanin kinetic degradation during storage at three temperatures (-14 ± 2 °C, 5 ± 1 °C and 21 ± 0,7 °C). In consequence, an extract was obtained with an anthocyanin content of 165 ± 9 mg cyanidin-3-O-glucoside/L, an antioxidant capacity of 464 ± 19 and 366 ± 7 μmol Trolox/100 g extract according to FRAP and DPPH assays respectively, and a vitamin C content of 2.07 ± 0.04 mg ascorbic acid/100 g extract. The degradation kinetics was defined by order one with the following degradation constants: 2,1·10-3, 8,6·10-3 and 2,7·10-2 days-1 for -14 ± 2 °C, 5 ± 1 °C and 21 ± 0,7 °C, respectively, which corresponds to an activation energy of 46.0·10-3 J/mol. Therefore, it is concluded that is possible to obtain, from purple passion fruit epicarp, high-value compounds extract rich, such as anthocyanin, that is affected by storage temperature, which is an important factor during its use in food matrices.

Resumo O maracujá roxo é uma fruta nativa da região amazónica cujo epicarpo é um subproduto com alto potencial em antioxidantes como as antocianinas. Por conseguinte, o objectivo deste estudo foi a extracção por solventes a partir de epicarpo para se obter um extracto rico em antocianinas, caracterizar a sua capacidade antioxidante e executar a cinética de degradação de antocianinas monoméricas durante o armazenamento a três temperaturas (-14 ± 2 °C, 5 ± 1 °C e 21 ± 0,7 °C). Portanto, obteve-se um extracto contendo antocianina 165 ± 9 mg de cianidina-3-glucósido ou/L, a capacidade antioxidante de 464 ± 19 e 366 ± 7 micromol Trolox/100 g de extrato de acordo com o ensaio de FRAP e DPPH, e vitamina C de 2,07 ± 0,04 mg de ácido ascórbico/100 g de extrato. A cinética de degradação foi definida por ordem um com as seguintes constantes: 2,1·10-3, 8,6·10-3 e 2,7·10-2 dias-1 para -14 ± 2 °C, 5 ± 1 °C e 21 ± 0,7 °C respectivamente, gerando uma energia de ativação de 46,0·103 J/mol. Portanto, conclui-se que é possível obter, a partir de gulupa epicarpo, extrai rico em compostos de alto valor, tais como as antocianinas, as quais são afectadas por temperatura de armazenamento, sendo este um factor para ter em conta a sua aplicação em matrizes alimentares.

Vacuum pulsed drying characteristics of Lycii Fructus based on Weibull distribution model / 中草药

Objective To mitigate Lycii Fructus surface crust and save drying time during drying process, vacuum pulsed drying technology was applied to dry Lycii Fructus so as to investigate moisture diffusion regulation and build the drying model. Methods The effect of different drying temperature (50, 55, 60, and 65 ℃), vacuum pressure holding time (5, 10, 20, and 30 min), and atmosphere pressure holding time (2, 4, and 8 min) on drying characteristics, moisture diffusion coefficients and drying activation energy was explored in vacuum pulsed drying process. Weibull model distribution was used to simulate and analyze Lycii Fructus drying curves. Results All the drying temperature, atmosphere pressure holding time, and vacuum pressure time holding time had significant influence on drying time. When drying temperature, atmosphere pressure holding time, and vacuum pressure time holding time was 60 ℃, 4 min, and 10 min, respectively, the minimum drying time was achieved to be 284 min. Weibull distribution model can be well described the vacuum pulsed drying process of Lycii Fructus. The scale parameter was related to drying time and decreased as drying temperature increased. The drying temperature, atmosphere pressure holding time, and vacuum pressure time holding time had little influence on the shape parameter. The shape parameter was associated with drying method. The moisture diffusion coefficient and activation energy were calculated to be 2.02 × 10-8-3.56 × 10-8 m2/s and 36.27 kJ/mol, respectively. Conclusion Weibull distribution model can well describe the moisture diffusion regulation of vacuum pulsed drying process of Lycii Fructus. The drying result had a great significance for predicting, controlling and optimizing drying process. On the other hand, the research could provide technical basis for industrial drying of Lycii Fructus by vacuum pulsed drying technology.

Diurnal variation of methane emission from a paddy field in Brazilian Southeast / Variação diurna da emissão de metano em arroz irrigado no Sudeste do Brasil

ABSTRACT: This study aimed to investigate the diurnal variation of methane (CH4) emission in a flooded-irrigated rice field at different stages of the plant development under tropical climate in three growing seasons, in order to determine the most appropriate time for gas sampling in the Brazilian Southeast region. It aimed also to verify correlations between CH4 flux and air, water and soil temperatures, and solar radiation. The CH4 emissions were measured every 3-hour interval on specific days in different development stages of the flooded rice in the Experiment Station of the Agência Paulista de Tecnologia dos Agronegócios (APTA), Pólo Regional Vale do Paraíba, at Pindamonhangaba, State of São Paulo (22°55' S, 45°30' W), Brazil. Different CH4 emission rates were observed among the plant growth stages and also among the growing seasons. The CH4 emission showed high correlation with the soil temperature at 2cm depth. At this depth, the CH4 emission activation energy in response to soil temperature was higher in the stage R2. Emission peaks were observed at afternoon, while lower fluxes were recorded at the early morning. The most appropriate local time for gas sampling was estimated at 12:11:15a.m.±01:14:16 and 09:05:49p.m.±01:29:04.

RESUMO: Este estudo teve como objetivo investigar a variação diurna de emissões de metano (CH4) em uma lavoura de arroz irrigado por inundação em diferentes estágios de desenvolvimento de plantas de arroz irrigado, sob clima tropical, em três estações de crescimento, para determinar o período de tempo mais apropriado à amostragem de gás na região Sudeste do Brasil. O trabalho objetivou também verificar correlações entre o fluxo de CH4 e as temperaturas do ar, da água e do solo e a radiação solar. As emissões diurnas de CH4 foram medidas a cada intervalo de três (3) horas em dias específicos em diferentes estágios de desenvolvimento da planta de arroz inundado na Estação Experimental da Agência Paulista de Tecnologia dos Agronegócios (APTA), Pólo Regional Vale do Paraíba, em Pindamonhangaba, Estado de São Paulo (22°55' S, 45°30' W), Brasil. Diferentes taxas de emissão foram observadas entre os estágios de desenvolvimento da planta avaliados e também entre as estações de cultivo. A emissão de CH4 mostrou alta correlação com a temperatura do solo a 2cm de profundidade. Nesta profundidade, a energia de ativação da emissão de CH4 em resposta à temperatura do solo foi maior no estágio R2. Os picos de emissão foram observados no período da tarde, enquanto que menores fluxos foram registrados no início da manhã. O horário mais apropriado para amostragem de gás foi estimado em 12:11:15a.m.±01:14:16 and 09:05:49p.m.±01:29:04.

Asymptotic Approximations to the Isothermal Pyrolysis of Deodara Leaves using Gamma Distribution / Aproximaciones asintóticas a la pirólisis isotérmica de hojas de deodara usando la distribución gamma / Aproximações assintóticas à pirólise isotérmica de folhas de deodara com a distribuição gamma

Abstract The main aim of this paper pivoted around the influence of some parameters relevant to biomass pyrolysis on the numerical solutions of the nth order distributed activation energy model (DAEM) using the Gamma distribution. The upper limit of 'dE' integral, frequency factor, reaction order, and the shape and rate parameters of the Gamma distribution are investigated. Analysis of the mathematical model is done with the help of asymptotic expansion.

Resumen El propósito principal de este artículo gira en torno de la influencia que tienen ciertos parámetros relacionados con la pirólisis de biomasa sobre las soluciones numéricas del modelo de energía de activación distribuida (MEAD) de orden n, usando la distribución Gamma. Se estudian el límite superior de la integral 'dE', el factor de frecuencia, el orden de reacción, y los parámetros de forma y velocidad de la distribución Gamma. El análisis del modelo matemático es realizado con ayuda de una expansión asintótica.

Resumo O objetivo principal deste artigo gira em torno da influencia de certos parâmetros relacionados à pirólise de biomassa nas soluções numéricas do modelo de energia de ativação distribuída (MEAD) de orden n, usando a distribuição Gamma. São estudados o limite superior da integral 'dE', o fator de frequência, a ordem da reação, e os parâmetros de forma e velocidade da distribuição Gamma. A análise do modelo matemático é realizada com a ajuda de uma expansão assintótica.

Drying kinetics and mathematical modeling of Erzhi Pills during hot-air drying process / 中草药

Objective: To study the change rule of water content in the drying process of hot air drying of thin layer drying characteristic and model research, and to provide reference for improving the quality of Erzhi Pills (EP). Methods: The moisture ratio, drying rate of dry basis, and drying rate curves along with the change of drying time and relationship between dry basis moisture content and drying rate of EP were studied using a hot air dryer at five levels of drying air temperature in the range of 50-90 ℃. The model was fitted and verified by the empirical model Henderson & Pabis model, Newton model, Page model, Logarithmic model, two term exponential model, Wang & Singh model, Midilli et al. model, etc. Meanwhile, based on Fick's diffusion law, the effective diffusion coefficients of water (Deff) and activation energy value in EP were calculated. Results: The drying curves of EP show that the moisture ratio and drying rate of EP were closely related to the temperature of drying medium, and the moisture of the material decreases with the prolonged drying time. It could be seen from the drying rate curve that the drying rate increased with the increase of hot air temperature, and the migration of moisture was accelerated. By comparing the correlation coefficient (R2), chi-square (χ2) and standard error (RMSE), we could see that the mean value of R2 of model number 7 was the maximum, the χ2 and RMSE mean were the smallest (0.996 86, 2.43 × 10−4, and 1.93 × 10−4), respectively. The results showed that the model number 7 could describe and predict the drying process of the pills. The experimental data had the effective diffusion coefficient (Deff) value of 8.6 × 10−11—3.13 × 10−10 m2/s, and the activation energy (Ea) was 30.97 kJ/mol. Conclusion: The hot air drying process of EP can be modeled and verified. The research provides a new way to explore the drying characteristics and quality of pills.

Ajuste de modelos e difusividade efetiva na secagem de folhas de Azadirachta indica A. Juss / Ajuste de los modelos y la difusividad efectiva en el secado de las hojas de Azadirachta indica A. Juss / Adjustment of models and effective diffusivity in the drying of Azadirachta indica A. Juss. leaves

Introdução: a espécie Azadirachta indica A. Juss. conhecida como neem indiano, possui ampla utilização nas áreas da medicina, agropecuária e cosmética, proporcionada particularmente pelas folhas desidratadas. Devido à importância da espécie, tem-se a necessidade de conhecimentos específicos no seu pré-processamento. Objetivo: determinar a curva de secagem, ajustar modelos não lineares aos dados, estimar o coeficiente de difusividade efetiva e a energia de ativação durante a secagem das folhas de A. indica, em diferentes temperaturas. Métodos: as folhas da referida espécie foram submetidas à secagem em diferentes temperaturas com quatro repetições em secador de camada fixa. Utilizaram-se doze modelos para testar o comportamento da cinética de secagem, e seleciono-os que melhor desempenharam respostas funcionais considerando a magnitude do coeficiente de determinação, qui-quadrado, erro médio relativo e desvio padrão. Ainda, ajustou os dados, ao modelo matemático da difusão líquida com a solução analítica para a placa plana infinita, com aproximação de oito termos. Os gráficos foram elaborados pelo Sigma Plot. Resultados: evidenciou ajuste satisfatório para os modelos de Verma, Newton, Midilli, Logarítmico e Aproximação da Difusão, porém selecionou-se o modelo de Newton por apresentar maior simplicidade de aplicação. Constatou-se que com aumento da temperatura, ocorre um decréscimo no tempo de secagem e aumento na intensidade do fenômeno de transporte de água. Conclusões: a energia de ativação foi de 27,77 kJ mol-1. O modelo de Newton pode ser utilizado para descrever a cinética de secagem das folhas de A. indica. A energia de ativação se mostrou dentro do intervalo indicado para produtos agrícolas(Introdução: a espécie Azadirachta indica A. Juss. conhecida como neem indiano, possui ampla utilização nas áreas da medicina, agropecuária e cosmética, proporcionada particularmente pelas folhas desidratadas. Devido à importância da espécie, tem-se a necessidade de conhecimentos específicos no seu pré-processamento. Objetivo: determinar a curva de secagem, ajustar modelos não lineares aos dados, estimar o coeficiente de difusividade efetiva e a energia de ativação durante a secagem das folhas de A. indica, em diferentes temperaturas. Métodos: as folhas da referida espécie foram submetidas à secagem em diferentes temperaturas com quatro repetições em secador de camada fixa. Utilizaram-se doze modelos para testar o comportamento da cinética de secagem, e seleciono-os que melhor desempenharam respostas funcionais considerando a magnitude do coeficiente de determinação, qui-quadrado, erro médio relativo e desvio padrão. Ainda, ajustou os dados, ao modelo matemático da difusão líquida com a solução analítica para a placa plana infinita, com aproximação de oito termos. Os gráficos foram elaborados pelo Sigma Plot. Resultados: evidenciou ajuste satisfatório para os modelos de Verma, Newton, Midilli, Logarítmico e Aproximação da Difusão, porém selecionou-se o modelo de Newton por apresentar maior simplicidade de aplicação. Constatou-se que com aumento da temperatura, ocorre um decréscimo no tempo de secagem e aumento na intensidade do fenômeno de transporte de água. Conclusões: a energia de ativação foi de 27,77 kJ mol-1. O modelo de Newton pode ser utilizado para descrever a cinética de secagem das folhas de A. indica. A energia de ativação se mostrou dentro do intervalo indicado para produtos agrícolas(AU)

Introducción: la especie Azadirachta indica A. Juss. conocida como indiano, posee amplia utilización en las áreas de la medicina, agropecuaria y cosmética, proporcionada particularmente por las hojas deshidratadas. Debido a la importancia de la especie, existe la necesidad de un conocimento específico en su pre-procesamiento. Objetivo: determinar la curva del secado, ajustar los modelos no lineales con los datos y estimar el coeficiente de difusividad efectiva y de la energia de activación durante el secado de las hojas de A. indica, a diferentes temperaturas. Métodos: las hojas de dicha especie, fueron sometidas a un secado a diferentes temperaturas con cuatro repeticiones en el secador de capa fija. Se utilizaron doce modelos para probar el comportamiento de la cinética de secado, y se seleccionaron según los que mejor desempeñaron respuestas funcionales, teniendo en cuenta la magnitud del coeficiente de determinación, chi-cuadrado, error medio relativo y la desviación típica. Además, se ajustaron los datos al modelo matemático de difusión líquida con la solución analítica para la placa plana infinita, con la aproximación de 8 terminos. Los gráficos fueron confeccionados por Sigma Plot. Resultados: se mostró un ajuste satisfactório para los modelos de Verma, Newton, Midilli, Logarítmico y la aproximación de difusión, sin embargo se selecionó el modelo de Newton, por presentar mayor simplicidad de aplicación. Se constató que con el aumento de la temperatura ocurre una disminución en el tiempo de secado y aumento en la intensidad del fenomeno de transporte del agua. Conclusiones: la energia de activación fue de 27,77 kJ mol-1. El modelo de Newton puede ser utilizado para describir la cinética de secado de las hojas de A. indica. La energía de activación se mostró dentro del alcance indicado para productos agrícolas(AU)

Introduction: The species Azadirachta indica A. Juss, commonly known as Indian neen, is broadly used in medicine, agriculture and the cosmetic industry, mainly in the form of dehydrated leaves. Due to the importance of this species, specific knowledge is required for its preprocessing. Objective: Determine the drying curve, adjust non-linear models to the data, and estimate the effective diffusivity and activation energy coefficient during the drying of A. indica leaves at different temperatures. Methods: Leaves from the study species were dried at different temperatures with four replications in the fixed layer dryer. Twelve models were used to test the behavior of the drying kinetics. These were selected from among those providing better functional responses, bearing in mind the magnitude of the determination coefficient, chi-square, relative mean error and typical deviation. Additionally, data were adjusted to the liquid diffusion mathematical model with the analytical solution for the infinite plane plate with an approximation of 8 terms. The charts were developed by Sigma Plot. Results: A satisfactory adjustment was achieved for the models Verma, Newton, Midilli, logarithmic, and diffusion approximation, but the Newton model was chosen, due to the simplicity of its application. It was found that as temperature increases, there is a decrease in drying time and an increase in water transport intensity. Conclusions: Activation energy was 27.77 kJ mol-1. The Newton model may be used to describe the drying kinetics of A. indica leaves. Activation energy was within the scope established for agricultural products(AU)

Modelagem matemática da secagem de frutos de crambe em camada delgada / Mathematical modeling of crambe fruits in thin layer drying

Objetivou-se no presente trabalho ajustar diversos modelos matemáticos ao processo de secagem dos frutos de Crambe abyssinica, em diversas condições de ar, bem como determinar o coeficiente de difusão efetivo e obter a energia de ativação. O trabalho foi realizado no Laboratório de Pós-colheita de Produtos Vegetais do Instituto Federal de Educação, Ciência e Tecnologia Goiano ­ Câmpus Rio Verde, Goiás, Brasil (IF Goiano ­ Câmpus Rio Verde). A colheita do crambe (Crambe abyssinica Hochst) da cultivar FMS Brilhante foi realizada manualmente, com o teor de água de 38,0±1,0 (% b.s.) e secados até o teor de 8,0±1,5 (% b.s.). A secagem foi realizada sob diferentes condições controladas de temperatura 35, 45, 60, 75 e 90 °C e umidades relativas de 20,9; 8,7; 6,8; 4,8 e 2,3%, respectivamente. Dentre os modelos analisados, Page foi o melhor que se ajustou aos dados nas diferentes condições do ar de secagem. O coeficiente de difusão efetivo aumentou com a elevação da temperatura apresentando valores de 2,84 x 10-11; 3,22 x 10-11; 5,00 x 10-11; 7,27 x 10-11 e 9,14 x 10-11 m2 s-1, para as temperaturas de 35, 45, 60, 75 e 90 °C, respectivamente, durante a secagem dos frutos de crambe. A relação entre o coeficiente de difusão efetivo e a temperatura de secagem pode ser descrita pela equação de Arrhenius, que apresenta uma energia de ativação para a difusão líquida na secagem de 20,998 kJ mol-1.

The arm in this work was set several mathematical models to the process of drying the fruits of Crambe abyssinica in different air conditions and to determine the effective diffusion coefficient and obtain the activation energy. The work was performed at the Laboratory of Postharvest Products Vegetables of Instituto Federal de Educação, Ciência e Tecnologia Goiano ­ Câmpus Rio Verde, Goiás, Brasil (IF Goiano - Câmpus Rio Verde). The harvest of crambe (Crambe abyssinica Hochst) cultivar FMS Brilhante was performed manually with a water content of 38.0±1.0 (% d.b.) and dried until the content of 8.0±1.5 (d.b.% ). The drying procedure was conducted under different temperature controlled conditions of 35, 45, 60, 75 and 90 °C and relative humidity of 20.9, 8.7, 6.8, 4.8 and 2.3% respectively. Among the models that presented the best fit to the experimental data, Page was the best fit for the data in the different conditions of the drying air. The effective diffusion coefficient increased with increasing temperature with values of 2.84 x 10-11, 3.22 x 10-11, 5.00 x 10-11, 7.27 x 10-11 and 9.14 x 10-11 m2 s-1, at temperatures of 35, 45, 60, 75 and 90 °C, respectively, during the drying of crambe fruits. The relation between the effective diffusion coefficient and the drying temperature may be described by the Arrhenius equation, which has an activation energy for the liquid diffusion in drying of 20.998 kJ mol-1.

Stability Evaluation and Degradation Kinetics of Ascorbic Acid in Baobab Fruit Pulp Formulated with the Seed Oil.

Aims: Baobab (Adansonia digitata) fruit pulp and the seed oil contain appreciable amount of vitamins and nutrients which help fight off diseases and afford commendable source of nourishment. It is essential to screen for the stability of the high vitamin C contents and validate the mechanism of its kinetic degradation in the fruit pulp with and without the oil extracted from seeds, during heat treatment. Experiments were planned according to standard methods and practices. Methodology: Ascorbic acid degradation in both raw baobab fruit pulp and the pulp formulated with baobab seed oil were investigated at varying temperatures (25–80ºC) and at different time intervals. Kinetic data analysis was then conducted by utilizing the absorbance data collected and the validated calibration curve of standard method using DCPIP to determine the ascorbic acid contents. Results: The results showed that reaction kinetics through heat treatments of the fruit pulp were well characterized by zero-order reactions. The activation energy (Ea) for the ascorbic acid degradation in the raw fruit pulp and the pulp treated with the seed oil were 0.000274 and 0.001903 Kcal/mol respectively. The shelf life of ascorbic acid in the formulated fruit pulp at 25ºC was approximately seven times that of the raw fruit pulp. Conclusion: The results indicate that the baobab seed oil exhibits both antioxidant enrichment and preservative properties.

Desarrollo y validación de un método analítico indicativo de estabilidad por HPLC para la cuantificación de Rosuvastatina Cálcica / Development and validation of a stability indicating analytical HPLC method for the quantification of Rosuvastatin Calcium

En este trabajo, fue desarrollado y validado un método indicador de estabilidad por cromatografía líquida, para ser aplicado al estudio cinético de Rosuvastatina Cálcica en diferentes valores de pH y temperatura. Las condiciones cromatográficas seleccionadas fueron: columna C18, 50 x 4.6 mm y 3,5 µm de tamaño de partícula; fase móvil MeOH: Agua-0.1%TFA, temperatura de la columna de la columna 25 ° C, y velocidad de flujo 1 mL/min. El método validado presentó una adecuada repetibilidad y precisión intermedia y una recuperación superior al 98%. Por otra parte, el método fue lineal en el rango de 10 a 150 ppm. En condiciones ácidas, fueron identificados tres posibles productos de degradación como: Rosuvastatina Lactona, Rosuvastatina Anti-isómero y Rosuvastatina Lactona Anti-isómero y en condiciones de degradación con la luz se identificaron dos posibles productos mayoritarios. El método validado puede ser empleado en estudios de estabilidad y de degradación cinética del fármaco.

In this work, a liquid chromatography stability-indicating method was development and validated to be applied at study the hydrolytic behavior of Rosuvastatin Calcium in different pH values and temperatures. The selected chromatographic conditions were a column C18 50 x 4.6 mm and 3.5 µm. The mobile phase was Methanol: Water-1%TFA; 25°C column temperature and flow rate 1 mL/min. The validation method exhibited an adequate repeatability and intermediate precision and a recovery higher than 98%. Furthermore, the method was lineal in range of 10 to 150 ppm. Under acidic conditions, three degradation products possible were identified as Rosuvastatin lactone, Rosuvastatin anti-isomer and Rosuvastatin lactone anti-isomer, with light were identified two major decomposition products. The validated method can be used in the stability studies and drug degradation kinetics.

Cinética de secagem de folhas de erva baleeira (Cordia verbenacea DC. ) / Drying kinetics of Cordia verbenacea DC. leaves

O objetivo do presente trabalho foi avaliar a cinética de secagem das folhas de erva baleeira (Cordia verbenacea DC.) bem como ajustar diferentes modelos matemáticos aos valores experimentais de razão de umidade. As folhas de erva baleeira foram colhidas com teor de água inicial de 75% b.u., sendo submetidas à secagem sob condições controladas de temperatura (40, 50, 60 e 70°C), até o teor de água aproximado de 10% b.u.. Aos dados experimentais foram ajustados oito modelos matemáticos citados na literatura específica e utilizados para a representação do processo de secagem de produtos agrícolas. Com base nos resultados obtidos pôde-se concluir que o modelo de Midilli é o que melhor representa a cinética de secagem das folhas de erva baleeira. O aumento da temperatura do ar de secagem promoveu maior taxa de remoção de água do produto. O coeficiente de difusão efetivo aumenta com a elevação da temperatura, sendo que sua relação com a temperatura de secagem pode ser descrita pela equação de Arrhenius. A energia de ativação para a difusão líquida durante a secagem das folhas de erva baleeira foi de 62,89 kJ mol-1 .

The objective of the present work was to evaluate the drying kinetics of Cordia verbanacea DC. leaves, as well to fit different mathematical models to the experimental data of the moisture ratio. The Cordia verbanacea Dc. leaves wers harvested with initial moisture content of approximately 75% w.b. and submitted to the drying process under controlled conditions of temperature (40, 50 60 and 70ºC), until the approximate moisture content of 10% w.b. Eight mathematical models mentioned or the specific literature were fitted to the experimental data and used to predict the drying process of the agricultural products. Based on the results obtained,swe have concluded that the Midilli model was the one that best represents the drying kinetics of Cordia verbanacea leaves. The temperature increase of the drying air promotes higher removal rate of water from the product. The effective diffusion coefficient increases with temperature elevation,tand its relationship with the drying temperature can be described through the Arrhenius equation, which presents activation energy of 62.89 kJ mol-1 for the liquid diffusion during the drying of the Cordia verbanacea DC. leaves.

Cinética de lixiviación de la corteza de mangle rojo en agua / Leaching kinetics of the red mangrove bark in water

Objetivo: determinar la naturaleza del fenómeno que rige la transferencia de masa durante la lixiviación del mangle rojo en agua mediante el estudio de la cinética del proceso. Métodos: se estudió la cinética de lixiviación de la corteza de mangle rojo en agua a escala de laboratorio, en una relación sólido/líquido 1:4 a diferentes temperaturas (25, 45, 70 y 90 °C). Para cada temperatura en particular se determinó la constante cinética a partir de la ecuación fundamental de la lixiviación mediante un modelo ajustado empleando el programa estadístico CurveExpert 1.4 para Windows. Resultados: los valores de la concentración de sólidos solubles totales correspondientes a 25 y 45 °C presentaron un incremento apreciable durante los primeros 20 min, y los correspondientes a 70 y 90 °C lo alcanzaron a los 30 min. El valor de la energía de activación obtenida en el experimento correspondió a 2,884 kJ. Conclusiones: la naturaleza de la lixiviación de la corteza de mangle rojo se produce por vía física.

Objective: to determine the type of phenomenon ruling the mass transfer during leaching of red mangrove in water by studying the kinetics of this process. Methods: the kinetics of leaching of red mangrove bark into water at lab was studied in a solid/liquid ratio of 1:4 at different temperatures (25, 45, 70 and 90 ºC). For each temperature, the kinetic constant was estimated from the fundamental leaching equation by a fitted model using the statistical program CurveExpert 1.4 for Windows. Results: the total soluble solid concentration values showed a sizeable increase at 25 and 45 °C in the first 20 minutes and at 70 and 90 °C in 30 minutes. The activation energy in the experiment amounted to 2.884 kJ. Conclusions: the leaching of the red mangrove bark is of physical origin.

Variação diária da emissão de metano em solo cultivado com arroz irrigado no Sul do Brasil / Diurnal variation of methane emission from a paddy field under rice cultivation in the Southern Brazil

O metano (CH4 ) apresenta um potencial de aquecimento 23 a 32 vezes maior do que o dióxido de C e a sua emissão diária em lavouras de arroz varia com a temperatura do solo e da água, e o metabolismo das plantas. O objetivo deste estudo foi determinar o horário apropriado à coleta de amostras de ar para quantificar a emissão média diária de CH4, informação fundamental para estudos visando a derivação de índices regionais de emissão desse gás. Três campanhas de monitoramento da emissão de CH4, com coletas em intervalos de 3h, foram realizadas nos estágios de emissão da panícula (campanha 1) e de maturação de grãos (campanhas 2 e 3) do arroz sob diferentes sistemas de cultivo (convencional e plantio direto) na safra 2002/2003, na Estação Experimental do Instituto Rio Grandense do Arroz, em Cachoeirinha, RS. A coleta das amostras de ar foi realizada com seringas de poliestireno em câmaras de alumínio de 1m², sendo que as análises de metano foram realizadas por cromatografia gasosa. A emissão diária de CH4 apresentou padrão similar nas três campanhas de amostragem independente do sistema de cultivo. A faixa de emissão mínima (4-19mg CH4m-2 h-1) ocorreu entre as 24 horas e o início da manhã seguinte (9 horas), e a faixa de emissão máxima (8-33mg CH4 m-2 h-1) do início à metade da tarde (12-15 horas). A emissão de CH4 foi relacionada à temperatura da água de inundação (campanhas 1 e 3) e do solo (campanha 2). Com base nas curvas de emissão diária e considerando aspectos operacionais como a viabilidade de análise cromatográfica das amostras no período de 24h após a coleta, o intervalo entre 9 e 12 horas é recomendado para a avaliação das emissões de CH4 em lavouras de arroz irrigado quando objetiva-se a obtenção de valores equivalentes à emissão média diária desse gás. Acredita-se que a alta relação entre a temperatura e a emissão de metano valida esse procedimento para as sub-regiões produtoras de arroz no Sul do Brasil (região litorânea e Sul...

Methane (CH4) has a global warming potential 23 to 32 times higher than carbon dioxide and its emission rate in rice fields should vary daily with water and soil temperature, and plant metabolism. This study aimed to identify the appropriate time interval for air sampling in order to quantify the mean daily CH4 emission rate, key information to future studies aiming the derivation of regional indexes of CH4 emission. Three campaigns were performed to evaluate diurnal variation in CH4 emissions (3h interval) from continuously flooded rice (Oryza sativa L. cv. 'IRGA-422 CL') fields at different crop stages (panicle differentiation and ripening) and management systems (conventional tillage-CT and no-tillage-NT) during 2002/2003 crop season in long-term experiment at the Instituto Rio Grandense do Arroz (IRGA), in Cachoeirinha, RS, Brazil. Static chamber method was used and the air samples collected with polystyrene syringes were analyzed by gas chromatography. Methane emission showed a same diurnal pattern in the three campaigns in the both tillage systems. The maximum range of emission (8-33mg CH4m-2 h-1) was observed in the early afternoon (12.00 to 15.00p.m.) followed by a decline to a minimum around midnight to next morning (4-19mg CH4 m-2 h-1), in which fluxes were related to flood water temperature (campaign 1 and 3) or soil temperature (campaign 2). Taking into account the daily emission curves, plus operational aspects like chromatographic analysis of samples into the 24h period after air sampling, the time interval from 9.00 to 12.00a.m. is recommended to studies aiming to evaluate mean daily CH4 emission in rice fields. The close relationship between temperature and methane emission allows us infer about the suitability of the gas sampling procedure for the different rice sub-regions of South of Brazil (littoral region and south of RS, and south of SC) that present the same daily behavior of solar radiation and air temperature...