Secagem do resíduo industrial da acerola em leito de jorro: estudos fluidodinâmicos e análise do desempenho do secador

In this research, the drying process of acerola waste was investigated by using a spouted bed drier. The process was conducted using high density polyethylene inert particles with the objective of producing an ascorbic acid-rich final product. The fruit waste was ground and used to prepare different water-maltodextrin suspensions. Initially, fluidynamical experiments were conducted in order to evaluate the feeding effect on the spouted bed drier fluidynamics behavior. The experimental planning 23 + 3 was used to investigate the effect of the following variables: solids concentration, drying air temperature, intermittence time, production efficiency, solids retention and product losses by elutriation of fine particles on drier walls. The effect of selected independent variables on the drier stability was also evaluated based on a parameter defined as the ratio between the feed suspension volume and the total inert particles volume. Finally, the powder quality was verified in experiments with fixed feed flow and varying air drying temperature, drying air velocity and intermittence time. It was observed that the suspension interferes in the spouted bed drier fluidynamics behavior, and higher air flow is necessary to stabilize the drier. The suspension also promotes the expansion of the spouted bed diameter, decreases the solid circulation and favors the air distribution at the flush area. All variables interfere in the spouted bed performance, and the solids concentration has a major effect on the material retention and losses. The intermittence time also has great effect on the stability and material retention. When it comes to production efficiency, the main effect observed was the drying air temperature. First order models were well adjusted to retention and losses data. The acerola powder presented ascorbic acid levels around 600 to 700 mg/100g. Similar moisture and ascorbic acid levels were obtained for powders obtained by spouted bed and spray drier. However, the powder production efficiency of the spray drier was lower when compared to spouted bed drier. When it comes to energetic analysis, the spray drier process was superior. The results obtained for spouted bed drier are promising and highly dependent on the operational parameters chosen, but in general, it is inferred that this drying process is adequate for paste and suspension drying

Avaliação da aplicação de modelos para a secagem de pastas e suspensões em leito de jorro com alimentação contínua

This work studies the development, implementation and improvement of a macroscopic model to describe the behavior of the spouted bed dryer with continuous feeding for pastes and suspensions drying. This model is based on the CST model (Freire et al., 2009) and the model of Fernandes (2005), whose theoretical foundation is based on macroscopic mass and heat balances for the three phases involved in the process: gas, liquid and solid. Because this technique is quite relevant, the studies of modeling and simulation of spouted bed drying are essential in the analysis of the process as a whole, because through them it is possible to predict and understand the behavior of the process, which contributes significantly to more efficient project and operation. The development and understanding of the phenomena involved in the drying process can be obtained by comparing the experimental data with those from computer simulations. Such knowledge is critical for choosing properly the process conditions in order to obtain a good drying efficiency. Over the past few years, researches and development of works in the field of pastes and suspensions drying in spouted bed has been gaining ground in Brazil. The Particulate Systems Laboratory at Universidade Federal do Rio Grande do Norte, has been developing several researches and generating a huge collection of experimental data concerning the drying of fruit pulps, vegetables pastes, goat milk and suspensions of agro-industrial residues. From this collection, some data of goat milk and residue from acerola (Malpighia glabra L.) drying were collected. For the first time, these data were used for the development and validation of a model that can describe the behavior of spouted bed dryer. Thus, it was possible to model the dryer and to evaluate the influence of process variables (paste feeding, temperature and flow rate of the drying air) in the drying dynamics. We also performed water evaporation experiments in order to understand and to study the behavior of the dryer wall temperature and the evaporation rate. All these analysis will contribute to future works involving the implementation of control strategies in the pastes and suspensions drying. The results obtained in transient analysis were compared with experimental data indicating that this model well represents the process

Concepção de um secador rotatório para secagem do cefalotórax do camarão

The present work has as objective the knowledge of the process of drying of the cephalothorax of shrimp to give support the industry to make possible the use of this byproduct. In this sense, the process conditions in this tray dryer and spouted bed were analyzed. With these results, it was projected and constructs a dryer with specific characteristics for the drying of the cephalothorax. The desorption isotherms were obtained by the dynamic method in the temperatures of 20, 35 and 50º C and in the interval of 10-90% of relative humidity. It was observed that the product in form of powder can be conserved with larger stability for lower relative humidity to 40%. The curves of drying of the dryer of fixed bed were adjusted for the models: single exponential, biparametric exponential and Page. The model biparametric exponential more adequately described all the drying conditions studied. The tests carry out in spouted bed showed high drying rate for the material in the paste form in beds active dynamicly-fluid, provely the necessity of a feeding in shorter intervals of time to increase the thermal efficiency of the process. The projected dryer, be considered the obtained results, it was a rotary dryer with inert bed, feed co-current, discharge in cyclone to take place the separation gas-solid, and feed carry out in intervals of 2 minutes. The optimization of the equipment projected it was accomplished used the complete factorial experimental design 24, this had as independent variables temperature velocity of the air, feed flow rate and encapsulated concentration (albumin), as variables answers the thermal efficiency, the moisture content of obtained powder, total time of test and the efficiency of production of powder in several points of processing. The results showed that the rotary dryer with inert bed can present, also, good results if applied industrially

Influência da geometria e da temperatura na cinética de secagem de tomate (Lycopersicum esculentum)

O tomate é um fruto muito perecível por causa do seu conteúdo de umidade. A secagem é uma das práticas industriais mais utilizadas em alimentos para manter a qualidade do produto final. A pesquisa foi desenvolvida para estudo dos parâmetros de secagem de tomate (Lycopersicon esculentum Mill), cv Carmen, com relação ao tipo de corte (meio e um quarto) e à temperatura de processo (60 e 70 ºC), bem como à escolha do tempo de secagem para a obtenção de um produto com umidade de 45% (base úmida). As cinéticas de secagem foram determinadas experimentalmente por convecção forçada e ajustadas ao modelo de Page. Os resultados obtidos mostraram que a geometria de corte influenciou na taxa de secagem e no tempo de desidratação. Os tomates cortados em quatro partes e desidratados a 70 ºC alcançaram umidade de 45% em menor tempo (10 horas), quando comparados aos tomates com o corte em metades. O modelo de Page forneceu bom ajuste nas cinéticas de secagem

Uma sequencia didática para o ensino da resolução da equação do 2. grau : adequação para o uso com professores

The present study aims to check whether the use of activities mediated by the History of Mathematics can contribute to improve the understanding of resolution the 2nd degree equation for teachers and undergraduates that reproduce methods of solving such equations, uncritically, without domain of the justifications for their actions. For this, we adapted a didactic sequence with activities that aims to cause a rediscovery of resolutive formula of 2nd degree equation through the method known as cut and paste. Finally, we presented the activity module containing the didactic sequence used during the study, as suggestion for use in the classroom, by the math teacher

O ritual simbólico do Ctrl+C (copiar ) e Ctrl+V (colar) no ensino médio

Nowadays, technology has a direct influence on the relationship student and teacher have with language. The internet is a powerful tool in helping work with the language and, through it, the knowledge comes to the student easily and intensely. Furthermore, this facility has enhanced and made visible what has been called, within the University community, "plagiarism generation." This work assumes that this generation has, in their written texts, symbolic movements similar to those of "copy and paste" applied to research work carried out by high school students. Taking this as starting point, this dissertation aims to analyze how high school students of the 1st year from a school in Natal (RN) construct texts, under the movements known as "Ctrl + c" and "Ctrl + v", with reference to the text of the "other". More specific issues are behind the general objective, namely: 1. how the student appropriates the source-text when he copies and pastes? 2. What are the categories of analysis that allow us to look analytically and theoretically for the "ctrl + c / ctrl + v" practice made by the student? 2. how the studies developed in the fields of "Genetic Criticism" (Grésillon, 1987), the "school manuscripts" (Calil, 2004) and "paraphrase" (Fuchs, 1982) may help in working with writing in the classroom standing as a possible way to minimize the copy and paste effects in the students texts? Thus, we observe the categories of analysis that allow us to look, theoretically and analytically, for the symbolic ritual of the "ctrl + c" (copy) and "ctrl + v" (paste) in high school. Our study shows that the student text is a "hybrid body" whose writing is a drawing entanglement because of the presence of the foreign text, verbatim, and the presence of linguistic elements to paraphrase the original text.This textual embodiment has, behind it, certain operations, namely: replacing, moving, adding and deleting statements. Given the specificity of the data and the research objectives, this study aligns with qualitative research methods (SILVERMAN, 2009) and falls within the knowledge field of Applied Linguistics, which is characterized especially by investigating problems, phenomena in which language in a real situation is taken as central (BRUMFIT, 1995).Theoretically, our work follows the approach of studies on the paraphrase (Fuchs, 1982, 1994a, 1994b; DAUNAY, 1997, 1999, 2002a, 2002b), the studies developed in the field of Genetic Criticism (Grésillon, 1987, 1994, 1992, 2008 ) and those developed by Eduardo Calil (2004) on "school manuscripts"

Study of the potentiometric response of the doped spinel Li1.05Al0.02Mn1.98O4 for the optimization of a selective lithium ion sensor

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Voltammetric performance and application of a sensor for sodium ions constructed with layered birnessite-type manganese oxide

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Development of an electrochemical sensor for potassium ions based on KSr(2)Nb(5)O(15) modified electrode

In the work described by this paper, we studied the development of a selective potassium ion sensor constituted of a carbon paste electrode modified (CPEM) with a novel KSr(2)Nb(2)O(15). The material KSr(2)Nb(2)O(15) is an oxide with the tetragonal tungsten bronze structure (TTB) type are in forefront both in the area of research as well as in industrial applications. The sensor response to potassium ions was linear in the concentration range 1.26 x 10(-5) at 1.62 x 10(-3) mol L(-1) (E (mV) = 32.7 + 51.1 log [K(+)]). The sensor based KSr(2)Nb(2)O(15), of the TTB-type presented very good potentiometric response, with a slope of 51.1 mV/dec (at 25 degrees C) and detection limit for the potassium ions of 7.27 x 10(-5) mol.L(-1)

Mutagenic Activity of Glycoallkaloids from Solanum palinacanthum Dunal (Solanaceae) in the Brazilian cerrado

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Efeito da concentração do amido de milho na liberação de paracetamol de comprimidos

Este trabalho avaliou a influência da concentração de amido de milho nas características físicas e na liberação in vitro de paracetamol a partir de comprimidos. Os granulados foram analisados quanto à granulometria e densidades aparentes bruta e compactada e os comprimidos quanto ao peso médio, espessura, dureza, friabilidade, tempo de desintegração. Os comprimidos foram preparados a partir de granulados obtidos por granulação a úmido, utilizando cozimento de amido a 10% como agente granulante, segundo três formulações. Embora os comprimidos obtidos tenham apresentado características dentro dos limites farmacopéicos, os resultados indicam que variações da concentração de amido provocam diferenças nos diversos parâmetros físicos estudados. Concentração mais alta de amido em pó dá origem, provavelmente, à interação entre os componentes da fórmula, interferindo na liberação in vitro do fármaco. Isto demonstra a importância de se otimizar a concentração dos adjuvantes numa formulação de comprimidos, pois, embora uma pequena variação nesta concentração não exerça efeito significativo no tempo de desintegração, a quantidade de fármaco liberado pode ser substancialmente alterada.

Adsorption and detection of DNA dendrimers at carbon electrodes

Dendritic nucleic acids are highly branched and ordered molecular structures, possessing numerous single-stranded oligonucleotide arms, which hold great promise for enhancing the sensitivity of DNA biosensors. This article evaluates the interfacial behavior and redox activity of nucleic acid dendrimers at carbon paste electrodes, in comparison to DNA. Factors influencing the adsorption behavior, including the adsorption potential and time, solution conditions, or dendrimer concentration, are explored. The strong adsorption at the anodically pretreated carbon surface is exploited for an effective preconcentration step prior to the chronopotentiometric measurement of the surface species. Coupled with the numerous guanine oxidation sites, such stripping protocol offers remarkably low detection limits (e.g., 3 pM or 2.4 femtomole of the I-layer dendrimer following a 15 min accumulation). The new observations bear important implications upon future biosensing applications of nucleic dendrimers.

Indicator-free electrochemical DNA hybridization biosensor

A new electrochemical hybridization biosensor protocol without an external indicator is described. The biosensor format involves the immobilization of inosine-substituted (guanine-free) probe onto the carbon paste transducer, and a direct chronopotentiometric detection of the duplex formation by the appearance of the guanine oxidation peak of the target. Such a use of the intrinsic DNA electrochemical response for monitoring hybridization events offers several advantages (over the common use of external indicators), including the appearance of a new peak, a Aat background, or simplicity. A 4 min short hybridization period allows a detection limit around 120 ng/ml. Performance characteristics of the sensor are described along with future prospects. (C) 1998 Elsevier B.V. B.V. All rights reserved.

Controle profissional de biofilme dentário como estratégia para manutenção da saúde periodontal de pacientes com aparelho ortodôntico fixo: análise comparativa entre diferentes períodos

The presence of fixed orthodontics appliances interfere on sanitation, allowing periodontal diseases to appear, despite the fact patients keep on visiting the dentist every month. This research aims to determine a protocol for the mechanical control of the dental biofilm performed by the professional. A protocol that was able to maintain the periodontal health of the patients under orthodontic treatment with fixed appliances, and in order to do so, it used a non-controlled, randomized and blind clinical essay. The sample involved 40 adolescents who were under the installation of fixed orthodontics appliances and it was divided in three groups, as follows: monthly controlled group (group 1) composed of 11 patients, the quarterly controlled group (group 2) with 16 patients and the semestrial controlled group (group 3) with 13 patients. For data collection, an interview and clinical exams with probing depth measurement, quantity of keratinized mucosa, Gingival Index and the Plaque Index were used. On the initial exam all patients received brushing guidelines as well as the professional control of dental biofilm, with periodontal scaler, Robinson s brush and prophylactic paste. However, Group 1 returned every month for control procedures; Group 2 every three months and Group 3 after six months. The intervention had a six-month duration (for all the three groups), when all the exams were repeated by another examiner who did not know which group each patient was inserted in. Finally, the research concluded that despite the fact there is no statistically significant difference among the three groups, clinically the patients from the monthly group presented a better response to professional control, with less accumulation of dental biofilm and less rate of gingival inflammation. Thus, the mechanical control of the dental biofilm performed by the professional could not avoid gingival increase, characterized by the raise of probing depth measurement, neither the quantity of keratinized mucosa

Tomate salada: uma alternativa como fonte de antioxidante para uso tópico

Tomato Salad: An Alternative as Antioxidant Source for Topic Use. Tomato is the principal source of lycopene, a carotenoid with high antioxidant activity which can be used topically as a phytocosmetic to combat skin aging. The aim of this study was to get a lycopene-rich extract from salad tomato pulp. The extract was analyzed using UV/vis spectroscopy, thin layer chromatography and high performance liquid chromatography. Oxidant activity was analyzed using the free radical DPPH method. The presence of lycopene in the salad tomato was confirmed. It was present in the apolar fraction rich in carotenoids, which was 96.70% lycopene. In the evaluation of the antioxidant activity, using the radical DPPH, the extract showed activity (IC(50) = 0,311 mg/mL). We conclude that the salad tomato can be used as a source of antioxidants for topic use.