Development of a biosensor for urea assay based on amidase inhibition, using an ion-selective electrode

A biosensor for urea has been developed based on the observation that urea is a powerful active-site inhibitor of amidase, which catalyzes the hydrolysis of amides such as acetamide to produce ammonia and the corresponding organic acid. Cell-free extract from Pseudomonas aeruginosa was the source of amidase (acylamide hydrolase, EC 3.5.1.4) which was immobilized on a polyethersulfone membrane in the presence of glutaraldehyde; anion-selective electrode for ammonium ions was used for biosensor development. Analysis of variance was used for optimization of the biosensorresponse and showed that 30 mu L of cell-free extract containing 7.47 mg protein mL(-1), 2 mu L of glutaraldehyde (5%, v/v) and 10 mu L of gelatin (15%, w/v) exhibited the highest response. Optimization of other parameters showed that pH 7.2 and 30 min incubation time were optimum for incubation ofmembranes in urea. The biosensor exhibited a linear response in the range of 4.0-10.0 mu M urea, a detection limit of 2.0 mu M for urea, a response timeof 20 s, a sensitivity of 58.245 % per mu M urea and a storage stability of over 4 months. It was successfully used for quantification of urea in samples such as wine and milk; recovery experiments were carried out which revealed an average substrate recovery of 94.9%. The urea analogs hydroxyurea, methylurea and thiourea inhibited amidase activity by about 90%, 10% and 0%, respectively, compared with urea inhibition

Tactual perception: a review of experimental variables and procedures

This paper reviews literature on tactual perception. Throughout this review we will highlight some of the most relevant variables in touch literature: interaction between touch and other senses; type of stimuli, from abstract stimuli such as vibrations, to two- and three-dimensional stimuli, also considering concrete stimuli such as the relation between familiar and unfamiliar stimuli or the haptic perception of faces; type of participants, separating studies with blind participants, studies with children and adults, and an analysis of sex differences in performance; and finally, type of tactile exploration, considering conditions of active and passive touch, the relevance of movement in touch and the relation between exploration and time. This review intends to present an organised overview of the main variables in touch experiments, attending to the main findings described in literature, to guide the design of future works on tactual perception and memory.This work was funded by the Portuguese “Foundation for Science and Technology” through PhD scholarship SFRH/BD/35918/2007

Classificação do tomate por atacadistas e produtores Curitiba Classification of tomatoes by wholesalers and producers in Curitiba, Brazil

Identificou-se o sistema efetivamente utilizado para classificação do tomate para mesa por atacadistas e produtores em Curitiba. Verificou-se também por que não são adotadas as normas legais de classificação. Foram entrevistados 11 atacadistas e 31 produtores de tomate que comercializam sua produção na CEASA Curitiba. Outros dois produtores foram entrevistados em suas propriedades e acompanhados desde a produção até a comercialização. Após tabulação dos dados calculou-se a porcentagem de entrevistados enquadrados em cada questão, em relação ao número total de entrevistados. Constatou-se que há mais de uma linguagem de classificação no mercado e embora não haja padrões de classificação, essas linguagens são compreendidas no momento da comercialização. Para os atacadistas da CEASA Curitiba, a classificação do tomate baseia-se nas cores e nos tamanhos dos frutos. Os frutos podem ser verdes, coloridos (ou pintados) ou vermelhos (ou maduros) e apresentar tamanho Extra 3A ou boca 5 (diâmetro maior que 7,5 cm), Extra 2A ou bocas 6 ou 7 (diâmetro entre 6,2 e 7,5 cm), Extra 1A ou bocas 8 ou 9 (diâmetro entre 4,8 e 6,2 cm). Os frutos Extra 2A (médios) são os mais freqüentes no comércio. Já a maioria dos produtores classifica os frutos em graúdos, médios e miúdos, em uma clara correspondência com a classificação adotada pelos atacadistas. Ambos os sistemas de classificação diferem do oficial que, segundo a maioria de atacadistas e produtores, é difícil de aplicar, encareceria o produto final e levaria a um aumento considerável do volume de frutos a serem descartados. Por esses motivos, antes que as normas oficiais de classificação de tomate possam ser adotadas, é necessário que se disponibilizem para o setor produtivo tecnologias de produção e assistência técnica qualificada. É necessário ainda que as normas de classificação sejam internalizadas pelos agentes do mercado por meio de cursos e treinamentos que estimulem a sua adoção.<br>The effectively used system for classification of table tomatoes by wholesalers and producers was studied in Curitiba, Brazil. We also identified why the laws of classification are not adopted. Eleven wholesalers and 31 tomato planters, which sell their production in CEASA Curitiba, were interviewed. Other two producers were also interviewed in their properties and tracked from production to marketing. After tabulation of the data, we calculated the percentage of respondents in each issue framed in relation to the total number of interviewees. More than one language of classification was identified on the market, and although there are no patterns of grading standards, these languages are included on saling. For wholesalers of CEASA Curitiba, the classification of tomatoes is based on the color and fruit size. The fruits can be green, colorful (or painted) or red (or mature) and present size Extra 3A or mouth 5 (diameter greater than 7.5 cm), Extra 2A or mouths 6 or 7 (diameter between 6.2 and 7,5 cm), Extra 1A or mouths 8 or 9 (diameter between 4.8 and 6.2 cm). The fruits Extra 2A (average) are the most frequent in trade. Most producers rank the fruits in great, intermediate and little, in a clear correlation with the classification adopted by the wholesalers. Both rating systems differ from the official; according to the majority of wholesalers and producers, it is difficult to enforce, and the final product can become expensive and lead to a considerable increase in the discarded fruits. For these reasons, rather than official standards for the classification of tomatoes could be adopted, it is necessary to provide for the productive sector technologies and qualified technical assistance. It is also necessary that the rules of classification are internalized by the agents of the market through courses and training to encourage their adoption

Evaluating the Potential of Vegetation Indices in Detecting Drought Impact Using Remote Sensing Data in a Mediterranean Pinewood

© 2020, Springer Nature Switzerland AG. The Mediterranean ecosystem represents an important natural resource, being able to produce ecosystem services, has both economic and social repercussions, especially if located in urban and peri-urban areas. In the last decades, increased forest vulnerability is being reflected in a larger number of severe decline episodes associated mainly with drought conditions. In this context, the Mediterranean area shows high forest vulnerability and a subsequent decline in its natural renewal rate. In this context, the objective of this research is to evaluate the different vegetation indices to monitor the effect of drought on the health of the Castelporziano pine wood. For this purpose, we used the NDVI, NDII and NMDI, provided by ESA Sentinel-2 images and field observations, to monitor the health status of a historic pinewood that has recently been affected by a rapid spread of parasites (Tomicus destruens Woll.). The application of these indices, on the scale of the entire pinewood, showed that the NDVI and NDII indices differentiate better the changes in vegetative health status for the observed period than the NMDI. Moreover, NDVI and NDII were applied, based on the classifications made, to volume and age classes. Ultimately, these preliminary results require further studies to better understand the potential and limiting factors of the indices used in monitoring pinewoods under stress due to aridity

The letter knowledge assessment tool

Purpose: There is a need to develop letter knowledge assessment tools to characterise the letter knowledge in Portuguese pre-schoolers and to compare it with pre-schoolers from other countries, but there are no tools for this purpose in Portugal. The aim of this paper is to describe the development and validation procedures of the Prova de Avaliac¸ao de Compet ~ ^encias de Pr e-Literacia (PACPL), which assesses letter knowledge. Method: This study includes data that has been gathered in two phases: pilot and main study. In the pilot study, an expert panel of six speech and language pathologists analysed the instrument. Children (n ¼ 216) aged 5;0–7;11 participated in the main study that reports data related to the psychometric characteristics of the PACPL. Content validity, internal consistency, reliability and contributing factors to performance were examined statistically. Results: A modified Bland–Altman method revealed good agreement amongst evaluators. The main study showed that the PACPL has a very good internal consistency and high inter-rater (96.2% of agreement and a Cohen’s k value of 0.92) and intra-rater (95.6% of agreement and a Cohen’s k value of 0.91) agreement. Construct validity of the PCAPL was also assured (Cronbach’s a of 0.982). Significant differences were found between age groups with children increasing their letter knowledge with age. In addition, they were better at identifying than at producing both letter names and letter sounds. Conclusions: The PACPL is a valid and reliable instrument to assess letter knowledge in Portuguese children.publishe