Results of monitoring at the British library excavation

The main phase of excavation for the basements of the British Library at St Pancras, London, was completed in 1987. The project included basements extending up to 25 m deep, through the London Clay and into the Lambeth Group. The excavations were formed using both the top-down method and open excavation with ground anchors. Existing major buildings lie within 25 m of the site and London Underground tunnels lie below and adjacent to the site. The purpose of this paper is to present the results of displacement monitoring; they are summarised in the paper and presented in more detail in online supplementary data files. The retaining walls advanced towards the site by up to about 32 mm and the clays expanded rapidly on unloading beneath the excavations, causing the Victoria Line tunnels to heave by up to 22 mm. The slow progress of the project provided an unusual opportunity to monitor ground and structure movements in the surroundings before site activity began. Ironically, it was found that the largest settlements of adjacent buildings were caused by the installation of equipment intended to measure the settlements. Extensive condition surveys were carried out, but no damage to adjacent structures or tunnels has been recorded. </jats:p

Alchemy: re-visioning photography in a digital age

Ann Vardanega investigated the contemporary engagement with alternative (historical), photographic processes and whether this has produced a contemporary photographic aesthetic. She found the reasons included a co-dependent relationship between process; object and aesthetic as well as an underlying concept of authenticity and the significance of the link between subject, light, time and place

Bored pile design in stiff clay II:Mechanisms and uncertainty

The soil mechanics related to pile design in clay has been the subject of substantial engineering research. In a companion paper, various codes of practice were reviewed showing the effect on pile capacity of the different global factors of safety that emerge from the various partial factor combinations for the ultimate limit state. Factors of safety are generally specified based on the opinions of experts. In this paper an assessment will be made of various objective procedures that can be used to reduce uncertainty in the design process, especially regarding the adoption of a pile resistance model and the selection of a soil strength profile as part of a ultimate limit state check, and the estimation of pile head settlement in the context of a serviceability limit state check. It is shown that both total stress and effective stress calculation methods are applicable in London Clay. Estimates of settlement using a non-linear soil stress–strain relationship are made and compared with published data. It is shown that the compression of the concrete dominates the settlement of long piles. Given the low settlements observed, recommendations are made for a reduction in standard factors of safety for bored pile design in stiff clays. </jats:p

The plastic limit of clays

The plastic limit of soils was first described by Atterberg in 1911. The thread-rolling test was standardised at the US Public Roads Bureau in the 1920s and 1930s, and has subsequently become one of the standard tests of soil mechanics. This paper reviews the original definitions of plastic limit as proposed by Atterberg, and proposes that the brittle failure observed in the plastic limit test is caused by either air entry or cavitation in the clay. Critical state soil mechanics is used to show that the observed range of undrained shear strengths of soils at plastic limit is consistent with this hypothesis. The fallacy that strength at plastic limit is a constant is highlighted, and the implications for geotechnical practice are discussed. </jats:p

Uso de tecnologias limpas para a obtenção de biosurfactantes e carboidratos prebióticos a partir do Ginseng brasileiro (Pfaffia glomerata)

Orientadores: Maria Angela de Almeida Meireles Petenate, Diego Tresinari dos SantosTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de AlimentosResumo: O ginseng brasileiro (Pfaffia glomerata) é uma planta nativa do Brasil que apresenta uma rica composição de compostos bioativos, incluindo a beta-ecdisona que apresenta propriedades estimulantes, as saponinas com atividade surfactante e açúcares prebióticos que possuem atividade prebiótica. Diante destes aspectos, diferentes processos de extração foram estudados a fim de maximizar a recuperação dos compostos bioativos de interesse, bem como separá-los em diferentes frações, utilizando apenas solventes não tóxicos. Inicialmente, realizou-se um estudo técnico e econômico da extração de beta-ecdisona e açúcares prebióticos das raízes e partes aéreas do ginseng brasileiro empregando extração com água subcrítica. Os resultados demonstraram que é possível obter extratos das raízes com concentração de beta-ecdisona de 0,7% (base seca, b.s.), enquanto que os extratos das partes aéreas apresentaram apenas 0,3% (b.s.) de beta-ecdisona. Em relação à extração de açúcares prebióticos, os extratos obtidos das raízes apresentaram um teor de frutooligossacarídeos de até 8,8% (b.s.), o que faz desta matéria-prima uma importante fonte desses compostos. A avaliação econômica do processo de extração com água subcrítica considerou principalmente o teor de beta-ecdisona dos extratos obtidos e demonstrou que o processamento das raízes é técnica e economicamente mais favorável do que o processamento das partes aéreas. Considerando os resultados obtidos neste estudo e dados da literatura sobre extração de compostos bioativos do ginseng brasileiro, um processo de extração intensificado realizado em duas etapas foi proposto com o intuito de aumentar a recuperação de beta-ecdisona, saponinas e açúcares prebióticos das raízes de ginseng brasileiro. Realizou-se a primeira etapa com etanol e a segunda com água, ambas a 333 K e avaliou-se o efeito da pressão neste processo. Observou-se que para a obtenção de compostos bioativos das raízes de ginseng brasileiro, processos realizados a pressão ambiente apresentam maior recuperação dos compostos do que quando realizados a alta pressão. Nesse processo obteve-se um extrato etanólico com 5,6% (b.s.) de beta-ecdisona e 47% (b.s.) de saponinas com concentração micelar crítica (CMC) = 6 mg?mL-1. O extrato etanólico não apresentou açúcares prebióticos. Já extrato aquoso apresentou um teor de frutooligossacarídeos de 9% (b.s.), além de 0,5% (b.s.) de beta-ecdisona e 24% (b.s.) de saponinas com CMC = 18 mg?mL-1. Desta forma, o processo de extração intensificado permitiu a extração e fracionamento dos compostos bioativos das raízes de ginseng brasileiro, uma vez que foi possível obter um extrato etanólico rico em beta-ecdisona e saponinas e um extrato aquoso rico em açúcares prebióticos. A partir destes resultados, um estudo econômico foi realizado a fim de comparar diferentes cenários de produção para avaliar a viabilidade econômica do processo de extração intensificado. Esse estudo confirmou o processo intensificado como sendo a rota de produção de extratos das raízes de ginseng brasileiro economicamente mais viável. Ao final do desenvolvimento deste trabalho demonstrou-se que é possível substituir processos de extração convencionais por processos inovadores que não utilizam solventes tóxicos, minimizam a geração de resíduos através do melhor aproveitamento das matérias-primas e são mais eficientes do ponto de vista energético além de serem altamente promissores do ponto de vista econômicoAbstract: Brazilian ginseng (Pfaffia glomerata) is a native plant from Brazil that contains a rich composition of bioactive compounds, including beta-ecdysone with stimulating effects, saponins with surfactant activity and prebiotic sugars with prebiotic effects. In this context, different extraction process were studied to maximize the bioactive compounds recovery, as well as to fractionate them, using only non-toxic solvents. Firstly, a techno-economic evaluation of the extraction of beta-ecdysone from roots and aerial parts of Brazilian ginseng using subcritical water was performed. The results showed that is possible to obtain extracts from Brazilian ginseng roots with 0.7% (dry basis, d.b.) of beta-ecdysone, while the Brazilian ginseng aerial parts extracts yielded 0.3% (d.b.) of beta-ecdysone. In terms of prebiotic sugars, the extracts from Brazilian ginseng roots showed a fructooligosaccharides content of 8.8% (d.b.), which makes this raw material an important source of such compounds. Since to date the beta-ecdysone is the main compound with commercial value obtained from Brazilian ginseng, the economic evaluation of the subcritical water extraction process accounted only the beta-ecdysone content in the extracts. The economic evaluation showed that the manufacturing of roots was a great opportunity of business, while the manufacturing of the aerial parts should not be undertaken. Considering the results obtained in this study and data from literature about extraction of bioactive compounds from Brazilian ginseng, an intensified process was proposed to increase the beta-ecdysone, saponins and prebiotic sugars recovery from Brazilian ginseng roots. The intensified process was performed in two steps: the first step used ethanol as solvent and the second one used water as solvent, both at 333 K. The effect of pressure on this process was evaluated. It was observed that to obtain bioactive compounds from Brazilian ginseng roots, the use of ambient pressure yielded greater results than those obtained at high pressure. In this process, an ethanolic extract containing 5.6% (d.b.) of beta-ecdysone, 47% (d.b.) of saponins with critical micellar concentration (CMC) = 6 mg?mL-1 was obtained. No prebiotic sugar was detected in the ethanolic extract, otherwise, the aqueous extract showed a fructooligosaccharides content of 9% (d.b.) besides 0.5% (d.b.) of beta-ecdysone and 24% (d.b.) of saponins with CMC = 18 mg?mL-1. In this way, the intensified process allowed the extraction and fractionating of the bioactive compounds from Brazilian ginseng roots, since it was possible to obtain an ethanolic extract rich in beta-ecdysone and saponins and an aqueous extract rich in prebiotic sugars. Based on the experimental results, an economic study was developed aiming to compare different production scenarios to evaluate the economic viability of the intensified process. The study confirmed that the intensified process is the best way to produce Brazilian ginseng extracts. At the end of the development of this work, it was showed that it is possible replace conventional extraction processes by innovative processes, which use non-toxic solvents, reduces the residues generation and are more efficient from the energetic point of view. Furthermore, the proposed processes showed high economic feasibilityDoutoradoEngenharia de AlimentosDoutora em Engenharia de Alimentos2013/17260-5FAPESPCNP