CARACTERÍSTICAS DOS SOLOS UTILIZADOS NA PRODUÇÃO DE ADOBES NA PROVÍNCIA DE HUAMBO – ANGOLA

RESUMO Em Angola, a construção em terra constitui-se como uma herança histórica presente na cultura das populações. Numerosas edificações em terra crua, construídas com base em métodos e técnicas ancestrais, encontram-se distribuídas por todo o país. Existe um número considerável de estruturas em pau-a-pique, taipa e mais recentemente em BTC (Bloco de Terra Comprimida). Porém, o adobe constitui-se como a técnica mais utilizada entre as técnicas de construção em terra crua, principalmente usada pelas famílias de baixo rendimento. Face ao atual panorama de desenvolvimento do país, e considerando a possibilidade de integrar sistemas e materiais de construção tradicionais, que respeitem o meio ambiente e que se integrem harmoniosamente no seu habitat natural, uma das opções alternativas na construção atual passa por retomar as soluções antigas e os materiais tradicionais, como a construção em adobe. Associando o trabalho científico ao conhecimento ancestral detido pela população pode-se melhorar e otimizar estas soluções tradicionais, dando resposta às exigências atuais de sustentabilidade social, económica e ambiental. A Província de Huambo insere-se na principal unidade morfoestrutural de Angola, o Planalto Central, com cotas absolutas que podem atingir os 2600 m [Araújo & Guimarães, 1992]. A Oeste, o planalto é limitado pela Cadeia Marginal de Montanhas, com relevos de desníveis muito acentuados, onde se situam as zonas de maior altitude de Angola. Nos interflúvios e no sopé das montanhas desenvolvem-se solos lateríticos. Na Região Central de Angola abundam rochas granitóides, cuja alteração “in-situ” originou os denominados solos residuais. As propriedades texturais, geoquímicas e mineralógicas destes solos dependem não só da composição química da rocha mãe, mas principalmente das características geomorfológicas e climatéricas locais [Duarte et al, 2013]. Estes são os solos utilizados em grande parte das construções em terra existentes na região do Planalto Central. À medida que nos aproximamos do Litoral, os materiais de construção vão variando de acordo com a litologia local. O clima também varia entre estas regiões e, consequentemente, também varia a resistência e durabilidade da construção em adobe face aos agentes meteorológicos. Grande parte das edificações do Planalto Central de Angola é construída com adobe, que é um elemento construtivo com potencial degradação pela ação da água. Devido ao clima, subtropical, quente e húmido, na maior parte do território angolano (60% são planaltos com cerca de 1000 aos 2000 metros de altitude e uma extensa rede hidrográfica), estas construções podem ser vulneráveis e apresentar degradação precoce, agravada pela falta de conhecimento das propriedades dos geomateriais utilizados e das técnicas que permitem a sua estabilização e conservação. Será desejável, por isso, encontrar soluções para melhorar a durabilidade e resistência do adobe, na região em estudo. Neste trabalho, pretende-se avaliar as propriedades dos solos tipicamente utilizados nos adobes construídos com as técnicas locais, mediante a realização de ensaios laboratoriais que determinem as características mineralógicas (DRX), físicas (peso específico, porosidade, índice de vazios, textura, consistência) e mecânicas (resistência à compressão, permeabilidade, dureza do material aglomerado, durabilidade). A metodologia a seguir nestes estudos baseia-se na interpretação da informação recolhida na bibliografia disponível e na realização de entrevistas às populações locais de forma a compreender a experiência tradicional no que concerne aos materiais e técnicas utilizadas na construção em terra, o tempo de vida útil das construções, e o tipo e periodicidade das ações de manutenção adotadas. Proceder-se-á também à realização de ensaios laboratoriais nos adobes construídos com materiais e procedimentos tradicionais, nomeadamente em termos de durabilidade e erodibilidade (Ensaio de erosão pelo método de Geelong; Ensaio de avaliação do ciclo húmido/seco aplicando as normas neozelandesas 4297: 1998 - Engineering Design of Earth Buildings; 4297: 1998 - Materials and Workmanship for Earth Buildings; 4297: 1999 - Earth Build. Not Requiring Specific Design). Os resultados obtidos com esta investigação permitirão identificar, selecionar e caraterizar os geomateriais e métodos mais utilizados na construção em terra crua na Província de Huambo, em Angola, contribuindo para o desenvolvimento do conhecimento destas soluções construtivas sustentáveis com forte implantação nesta região. A partir da análise dos dados recolhidos será definida a estratégia para os passos seguintes deste projeto de investigação, que visa a proposta de soluções construtivas com melhores características de desempenho, conforto, segurança e durabilidade

Abacate: Características, Benefícios à Saúde E Aplicações

This study aimed to present a literature review about the characteristics, applications, and potential of avocado (Persea americana). Avocado is considered one of the main tropical fruits, as it contains fat-soluble vitamins which are less common in other fruits, besides high levels of protein, potassium and unsaturated fatty acids. Avocado pulp contains variable oil content, and is widely used in the pharmaceutical and cosmetics industry, and in the production of commercial oils similar to olive oil. This fruit has been recognized for its health benefits, especially due to the compounds present in the lipidic fraction, such as omega fatty acids, phytosterols, tocopherols and squalene. Studies have shown the benefits of avocado associated to a balanced diet, especially in reducing cholesterol and preventing cardiovascular diseases. The processed avocado pulp is an alternative to utilize fruits, which can be used in various value-added food products. Fluid extract of the avocado leaves is widely used in pharmaceutical products, mainly due to the diuretic characteristic of the present compounds in plant leaves. With the increasing research supporting the nutritional characteristics and benefits of avocado, the tendency is to increase the production and exploitation of this raw material in Brazil, as also observed in other countries. © 2016, Universidade Federal de Santa Maria. All rights reserved.46474775

Characterization of adobes in the Central Plateau of Angola.

In Angola, the earth construction constitutes part of the built and cultural her-itage. Numerous buildings made of raw earth, built with ancient techniques and methods, are distributed throughout the country. There are a considerable number of structures in wattle and daub, mud and more recently on CEB (Compressed Earth Block). But, adobe constitutes itself as the most widely used technique based on raw earth. Given the current development of the country, and the possibility of integrat-ing systems and alternative construction materials that respects the environ-ment, adobe construction is one of the most suitable options. Associating the scientific work to the ancestral knowledge, it can be improved and optimized these solutions, responding to the current social, economic and environmental requirements. This paper presents the results of a survey on the characterization of con-struction with raw earth in Central Plateau of Angola, involving the identifica-tion of collecting sites of the raw material, building methods, and the determi-nation of the properties of representative materials used in the adobe build-ings. The methodology followed in this research was based on the compilation of the information available in the literature, on interviews to the local popula-tions and on laboratory tests to characterize the physical properties (texture, consistency, density, etc.). The results of the research will identify and characterize the materials and methods used in the constructions with raw earth in Central Plateau of Ango-la, contributing to the development of knowledge of these sustainable solu-tions with a strong presence in this region

Mechanical properties of adobe blocks used in building construction in Huambo Province - Angola

Despite significant advances in building technologies with the use of conventional construction materials (as concrete and steel), which significantly have driven the construction industry, earth construction have demonstrated its importance and relevance, as well as it has matched in an efficient and eco-friendly manner the social housing concerns. The diversity of earth construction techniques allowed this material to adapt to different climatic, cultural and social contexts until the present time. However, in Angola, the construction with earth is still associated with population fringes of weak economic resources, for which, given the impossibility of being able to acquire modern construction materials (steel, cement, brick, among others), they resort to the use of available natural materials. Furthermore, the lack of scientific and technical knowledge justifies the negative appreciation of traditional building techniques, and the derogatory way how are considered the earth constructions in Angolan territory. Given the country's current development status, and taking into account the environmental requirements and the real socio-economic sustainability of Angola, it is considered that one of the viable and adequate options, could be the recovering and upgrading of the ancestral techniques of earth construction. The purpose of this research is to develop the technical and scientific knowledge in order to improve and optimize these construction solutions, responding to the real problems of housing quality as well as to the current social, economic and environmental sustainability requirements. In this paper, a description of the physical and mechanical characteristics of the adobes typically used in the construction of traditional houses in some localities of Huambo, province in Angola, is carried out. The methodology was based on mechanical in-situ testing in adobe blocks manufactured with traditional procedures: i) tensile strength evaluated with the bending test and compressive strength test on earth blocks specimens; and, ii) durability and erodibility test by Geelong method adopting the New Zealand standard (NZS) procedures (4297: 1998; 4297: 1998 and 4297: 1999). The results allow the characterization of the materials used in the construction of raw earth in the Huambo region, contributing to the development of knowledge of these sustainable and traditional housing constructive solutions with a strong presence in Angola [1, 2]. This study is part of a larger project in the area of Earth Construction [3], which aims to produce knowledge which can stimulate the use of environmental friendly construction materials and contribute to develop constructive solutions with improved performance, durability, comfort, safety and sustainability

Dynamic culturing of cartilage tissue: the significance of hydrostatic pressure

Human articular cartilage functions under a wide range of mechanical loads in synovial joints, where hydrostatic pressure (HP) is the prevalent actuating force. We hypothesized that the formation of engineered cartilage can be augmented by applying such physiologic stimuli to chondrogenic cells or stem cells, cultured in hydrogels, using custom-designed HP bioreactors. To test this hypothesis, we investigated the effects of distinct HP regimens on cartilage formation in vitro by either human nasal chondrocytes (HNCs) or human adipose stem cells (hASCs) encapsulated in gellan gum (GG) hydrogels. To this end, we varied the frequency of low HP, by applying pulsatile hydrostatic pressure or a steady hydrostatic pressure load to HNC-GG constructs over a period of 3 weeks, and evaluated their effects on cartilage tissue-engineering outcomes. HNCs (10 · 106 cells/ mL) were encapsulated in GG hydrogels (1.5%) and cultured in a chondrogenic medium under three regimens for 3 weeks: (1) 0.4MPa Pulsatile HP; (2) 0.4MPa Steady HP; and (3) Static. Subsequently, we applied the pulsatile regimen to hASC-GG constructs and varied the amplitude of loading, by generating both low (0.4 MPa) and physiologic (5 MPa) HP levels. hASCs (10x106 cells/mL) were encapsulated in GG hydrogels (1.5%) and cultured in a chondrogenic medium under three regimens for 4 weeks: (1) 0.4MPa Pulsatile HP; (2) 5MPa Pulsatile HP; and (3) Static. In the HNC study, the best tissue development was achieved by the pulsatile HP regimen, whereas in the hASC study, greater chondrogenic differentiation and matrix deposition were obtained for physiologic loading, as evidenced by gene expression of aggrecan, collagen type II, and sox-9; metachromatic staining of cartilage extracellular matrix; and immunolocalization of collagens. We thus propose that both HNCs and hASCs detect and respond to physical forces, thus resembling joint loading, by enhancing cartilage tissue development in a frequency- and amplitude-dependant manner.Fundação para a Ciência e a Tecnologia (FCT) - SFRH/BD/42316/200