Estudo sobre a influência da inserção do Massará em argamassas de assentamento de blocos cerâmicos / Study on the influence of insertion of Massará in ceramic blocks laying mortars

O massará é conhecido apenas na região de Teresina-PI. De acordo com Correia Filho (1997), é um material ligante, de pouca consistência, facilmente desagregável (friável), contendo seixos brancos de sílica. Este trabalho tem o objetivo de verificar a influência do massará, enquanto componente das argamassas de assentamento de blocos cerâmicos, que associado ao cimento portland e parcialmente ao agregado miúdo pode vir a formar a argamassa de assentamento. Tendo em vista que a areia utilizada em argamassas na cidade de Teresina é toda advinda dos rios, e o massará é extraído da lavagem do material que dá origem ao seixo encontrado em jazidas. Esse estudo visa à obtenção de um traço de argamassa obtido com a utilização do massará, onde serão feitos ensaios mecânicos e de caracterização do material em laboratório. Diversos traços serão experimentados e em seguida serão moldados corpos de prova e amostras para obtenção dos resultados da resistência e trabalhabilidade dos mesmos. Após a realização dos ensaios, será estudada a possibilidade de usá-lo como componentes das argamassas de assentamento utilizadas em construtoras de Teresina - PI

Aspectos quantitativos do crescimento do hibrido tambacu (femea de Colossoma macropomum x macho de Piaractus mesopotamicus) sob condições de criação intensiva

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciencias AgrariasFoi realizada uma análise quantitativa da criação intensiva do Tambacu, um híbrido resultando do cruzamento da fêmea do Tambaqui (Colossama macropomum) e macho de Pacu (Piaractus mesapotamicus), determinando-se a relação peso/comprimento, as curvas de crescimento e de biomassa. Testou-se o efeito de dois métodos de alimentação sobre o crescimento dos peixes. O estudo foi realizado no centro de Pesquisa e Treinamento em Aqüicultura - CEPTA/IBAMA em Pirassununga-SP, durante o período de 27 de março de 1990 a 31 de maio de 1991 (430 dias). Foram utilizados viveiros com volume de 300m3 e profundidade de 1m. A análise realizada indicou que o crescimento do tambacu é praticamente o mesmo (p > 0,05) quer alimentado com base na porcentagem da biomassa por dia de alimentação quer com o alimento fornecido "ad libitum". Foram analisados fatores ambientais que podem ter afetado o crescimento do híbrido, tais como fluxo da água (l/min), temperatura da água (oC) oxigênio dissolvido (mg/l). Verificou-se que a aplicação do modelo exponencial às curvas de crescimento e de biomassa resultou em procedimento adequado, permitindo sua adoção na análise de dados da piscicultura, principalmente para previsões de tamanho do peixe no período de crescimento favorável. Verificou-se que o sistema de fluxo de água contínuo pode aumentar a biomassa de peixes em 2,75 X, em 288 dias. Na região do experimento, a temperatura da água e o fotoperíodo foram mais favoráveis ao crescimento do tambacu no período de outubro a março

<b>Estimativa do tempo de vida útil de represa de pequeno porte</b> - DOI: 10.4025/actascitechnol.v31i1.1517

O trabalho foi realizado com o objetivo de comparar dois métodos para estimar o tempo de vida útil de um reservatório pequeno e raso, localizado no Município de Pirassununga, Estado de São Paulo: 1) sedimentométrico, com uso de câmaras de sedimentação, e 2) batimétrico. Na utilização do modelo para a estimativa do tempo de vida útil para a Represa Velha, para os dois métodos, a média anual entre os anos foi de 50 anos, apresentando-se semelhante entre os anos iniciais de 1998/1999, com 51 anos, e os anos finais de 2004/2005, com 46 anos, e oscilando entre os anos de 1999/2000, com 27 anos, e 2000/2001, com 76 anos. Os resultados obtidos no trabalho indicaram que é possível estimar o tempo de vida útil de represas de pequeno volume com o emprego do método sedimentométrico, conhecendo-se o valor do coeficiente de correção (K'). Este coeficiente é obtido a partir dos valores de tempo de vida útil, calculados pelos métodos sedimentométrico e batimétrico simultaneamente, durante o período de um ano

Rhoeo discolor leaf extract as a novel immobilizing matrix for the fabrication of an electrochemical glucose and hydrogen peroxide biosensor

A novel natural immobilizing matrix for the immobilization of glucose oxidase (GOx) and horseradish peroxidase (HRP) is presented in this article. The electrochemical biosensor was constructed by immobilizing the enzymes on Rhoeo discolor (Rd) leaf extract with 2.5% glutaraldehyde (GLD) on functionalized multiwalled carbon nanotubes (f-MWCNTs) modified graphite (Gr) electrode. The Gr/f-MWCNTs/(Rd-GLD)/GOx and Gr/f-MWCNTs/(Rd-GLD)/HRP biosensors showed excellent electrocatalytic activity concerning the detection of glucose and hydrogen peroxide. The physical morphology of the biosensors was studied using SEM and EDX. The electrochemical performance of the proposed biosensors was evaluated using cyclic voltammetry, differential pulse voltammetry and chronoamperometry. The effects of experimental variables such as pH, temperature, and applied potential on the current response of the biosensors were studied and optimized. The Gr/f-MWCNTs/(Rd-GLD)/GOx biosensor exhibited a rapid response time of less than 5 s, displayed a wide linear range of 0.5 to 28.5 mM, showed a low detection limit of 0.16 μM and revealed a high sensitivity of 15 μA mM-1 cm-2 for glucose. Similarly the Gr/f-MWCNTs/(Rd-GLD)/HRP biosensor showed a fast response time of 3 s, a good linear range of 0.2 to 6.8 mM with a 0.01 μM detection limit and an exceptional sensitivity of 2.1 mA mM-1 cm-2 for hydrogen peroxide. Subsequently, the practical applicability of the glucose biosensor for the analysis of glucose in Eleusine coracana wine and tender coconut water was examined while the Gr/f-MWCNTs/(Rd-GLD)/HRP modified electrode was tested for the determination of H2O2 in herbal bleach. In addition, the biosensors displayed long term stability, anti-interference ability and good reproducibility. © 2014 The Royal Society of Chemistry.

A novel bioassay based gold nanoribbon biosensor to aid the preclinical evaluation of anticancer properties

In this work, we report a microbial biosensor fabricated for the preclinical assay of anticancer compounds. Gold nanoribbons were used as a transducer for mounting the microbe. For the synthesis of these unique Au nanostructures, quercetin stabilized gold nanoparticles (Q-AuNPs) were synthesized as a first step using onion peel. Later, dityrosine peptide was used as a sacrificial template for the synthesis of the gold nanoribbons (AuNRs). The structural morphology of the as-synthesized Au nanomaterial was examined using UV spectroscopy, XRD, SEM and TEM. The AuNRs were found to be &lt;10 nm in diameter, which provided a good biocompatible environment and effective protection for the immobilization of Agrobacterium tumefaciens (At), a causative agent of crown gall disease. At is reported to cause tumors in plants through a tumorigenic mechanism similar to that of humans. Inhibition of At indicates that the inhibitory compound being screened exhibits anticancer activity. Clitoria ternatea (Ct) is traditionally used to cure many diseases and is known to possess anticancer activity. Therefore, we have used a Ct flower extract in the preclinical study of its anticancer activity against At by fabricating a simple electrochemical sensor. We have employed electrochemical techniques such as CV and EIS for the characterization of the developed microbial biosensor. Moreover, the as-synthesized AuNRs behave as an ideal transducer and platform, thus improving the electrode surface area and providing good biocompatibility for the immobilization of At. In contrast to other immobilization techniques and biosensors that often require elaborate procedures, cross-linking agents and rigorous chemical reactions, At was directly adsorbed onto the electrode under optimum conditions without any mediators. The results show that the developed biosensor is useful in the pre-clinical analysis of anticancer properties. Indeed the study examines the use of electrochemistry, demonstrating the rapid response and high sensitivity of the proposed sensor in contrast to bioassay procedures. In conclusion, the experimental results indicate that the developed biosensor accentuates the excellent properties of the synthesized AuNRs, which promises to be a novel avenue in designing biosensors. © 2016 The Royal Society of Chemistry.1

Development of a simple bioelectrode for the electrochemical detection of hydrogen peroxide using Pichia pastoris catalase immobilized on gold nanoparticle nanotubes and polythiophene hybrid

In this paper, a simple and innovative electrochemical hydrogen peroxide biosensor has been proposed using catalase (CATpp) derived from Pichia pastoris as bioelectrocatalyst. The model biocomponent was immobilized on gold nanoparticle nanotubes (AuNPNTs) and polythiophene composite using 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide and N-hydroxysuccinimide (EDC-NHS) coupling reagent. In this present work, we have successfully synthesized gold nanoparticles (AuNPs) by ultrasonic irradiation. The tubular gold nanostructures containing coalesced AuNPs were obtained by sacrificial template synthesis. The assembly of AuNPNTs onto the graphite (Gr) electrode was achieved via S-Au chemisorption. The latter was pre-coated with electropolymerized thiophene (PTh) to enable S groups to bind AuNPNTs. The combination of AuNPNTs-PTh, i.e., an inorganic-organic hybrid, provides a stable enzyme immobilization platform. The physical morphology of the fabricated biosensor Gr/PTh/AuNPNTs/EDC-NHS/CATpp was investigated using scanning electron microscopy and energy-dispersive microscopy. The analytical performance of the bioelectrode was examined using cyclic voltammetry, differential pulse voltammetry and chronoamperometry. Operational parameters such as working potential, pH, and thermal stability of the modified electrode were examined. The beneficial analytical characteristics of the proposed electrode were demonstrated. Our results indicate that the Gr/PTh/AuNPNTs/EDC-NHS/CATpp bioelectrode exhibits a wide linear range from 0.05 mM to 18.5 mM of H2O2, fast response time of 7 s, excellent sensitivity of 26.2 mA mM-1 cm-2, good detection limit of 0.12 μM and good Michaelis-Menten constant of 1.4 mM. In addition, the bioelectrode displayed good repeatability, high stability and acceptable reproducibility, which can be attributed to the AuNPNTs-PTh composite that provides a biocompatible micro-environment. © the Partner Organisations 2014.

An Electrochemical Perspective Assay for Anticancer Activity of Calotropis Procera Against Glioblastoma Cell Line (LN-18) using Carbon Nanotubes-Graphene Nano-Conglomerate as a Podium

In this article, we report the pre-screening of anti-cancer effect of Calotropis procera against glioblastoma cell lines (LN-18) by means of electrochemical methods. Soxhlet assisted extraction (SAE) has been employed to extract the polyphenol contents present in the leaf of Calotropis procera. The phytochemical analysis of the extract has been studied and the polyphenol contents were determined using Folin Ciocalteau method. To study the anticancer effects of the aqueous plant extract, a cytosensor (Gr/NT-G/LN-18) was fabricated and its possible mechanism for DNA binding was studied using graphite /poly(allylamine hydrochloride)/nanotube-graphene composite /polypyrrole /de-oxy ribonucleic acid (Gr/PAH/NT-G/PPy/DNA) modified electrode. The electrochemical characteristics of the proposed Gr/NT-G/LN-18 cytosensor towards the plant extract were evaluated using electrochemical techniques like cyclic voltammetry and differential pulse voltammetry. Scanning electron microscopy (SEM) and energy dispersive analysis of x-ray (EDAX) have been employed to study the physical characterization of the Gr/PAH/NT-G/PPy/DNA modified electrode. These results indicate that the plant extract has an ability to act as an antiglioblastoma against LN-18 cancer cells. Copyright © 2016 VBRI Press.

Synthesis of one-dimensional gold nanostructures and the electrochemical application of the nanohybrid containing functionalized graphene oxide for cholesterol biosensing

This manuscript reports a new approach for the synthesis of one dimensional gold nanostructure (AuNs) and its application in the development of cholesterol biosensor. Au nanostructures have been synthesized by exploiting β-diphenylalanine (β-FF) as an sacrificial template, whereas the Au nanoparticles (AuNPs) were synthesized by ultrasound irradiation. X-ray diffractometer (XRD), scanning electron microscope (SEM) and energy dispersive analysis of X-rays (EDAX) have been employed to characterize the morphology and composition of the prepared samples. With the aim to develop a highly sensitive cholesterol biosensor, cholesterol oxidase (ChOx) was immobilized on AuNs which were appended on the graphite (Gr) electrode via chemisorption onto thiol-functionalized graphene oxide (GO-SH). This Gr/GO-SH/AuNs/ChOx biosensor has been characterized using cyclic voltammetry (CV), electrochemical impedance spectroscopy and chronoamperometry. CV results indicated a direct electron transfer between the enzyme and the electrode surface. A new potentiostat intermitant titration technique (PITT) has been studied to determine the diffusion coefficient and maxima potential value. The proposed biosensor showed rapid response, high sensitivity, wide linear range and low detection limit. Furthermore, our AuNs modified electrode showed excellent selectivity, repeatability, reproducibility and long term stability. The proposed electrode has also been used successfully to determine cholesterol in serum samples. © 2016 Elsevier B.V.