Journal of Architecture and Urbanism - Rethinking Le Corbusier: Urban Design and History

This is much more than a mere compilation of texts about Corbusian architecture. The articles gathered here focus on Le Corbusier’s reflections about the public space of earlier times and its influence upon his own output, the relationship of his designs with the pre-existing city, and other subjects drawn from all periods of his career and training that clarify the affinity that he established with the past through urban design. They are very heterogeneous, pointing off in different directions and marking the most diverse interests. But at the same time they are interconnected, in that they seek to shed light on the affinity that Le Corbusier established with the past from the point of view of urban design, and open up new perspectives about the public space in his work and its controversial relationship with history. This special issue thus bears witness once again to Le Corbusier’s inexhaustible legacy, but also to the usefulness of research on his work and thought – a subject about which it seemed that everything had already been said when, paradoxically, we now know that there is still almost everything left to say.

Rethinking Le Corbusier: Urban Design and History

It is generally assumed that Le Corbusier’s urban planning made a break with the past, and that the public spaces designed by him had nothing to do with anything that existed before – a conviction fostered by both the innovative character of his proposals and by the proliferation in his manifestos of watchwords that mask any evocation of the past – words like civilisation machiniste, l’esprit nouveau, l’architecture de demain. However, in his writings, Le Corbusier often mentioned the powerful analogy that exists between the architecture of other times and the logic of modern production. Vers une architecture, for example, contains a mixture of photographs showing silos, cars, aeroplanes, ships (i.e. the fruits of 19th and 20th century civil architecture and mechanical engineering) alongside photographs of Greek and Roman buildings. While Le Corbusier, at the end of the 1920s, claimed “I have only one teacher: the past; only one education: the study of the past”, a series of sketches in the first volume of the Œuvre complète, done during his youth at the archaeological sites visited during his Grand Tour, shows that his interest in the past went far beyond a simple reference.

Development and optimisation of protocols for surface cleaning of cultural heritage metals

The conservation and valorisation of cultural heritage is of fundamental importance for our society, since it is witness to the legacies of human societies. In the case of metallic artefacts, because corrosion is a never-ending problem, the correct strategies for their cleaning and preservation must be chosen. Thus, the aim of this project was the development of protocols for cleaning archaeological copper artefacts by laser and plasma cleaning, since they allow the treatment of artefacts in a controlled and selective manner. Additionally, electrochemical characterisation of the artificial patinas was performed in order to obtain information on the protective properties of the corrosion layers. Reference copper samples with different artificial corrosion layers were used to evaluate the tested parameters. Laser cleaning tests resulted in partial removal of the corrosion products, but the lasermaterial interactions resulted in melting of the desired corrosion layers. The main obstacle for this process is that the materials that must be preserved show lower ablation thresholds than the undesired layers, which makes the proper elimination of dangerous corrosion products very difficult without damaging the artefacts. Different protocols should be developed for different patinas, and real artefacts should be characterised previous to any treatment to determine the best course of action. Low pressure hydrogen plasma cleaning treatments were performed on two kinds of patinas. In both cases the corrosion layers were partially removed. The total removal of the undesired corrosion products can probably be achieved by increasing the treatment time or applied power, or increasing the hydrogen pressure. Since the process is non-invasive and does not modify the bulk material, modifying the cleaning parameters is easy. EIS measurements show that, for the artificial patinas, the impedance increases while the patina is growing on the surface and then drops, probably due to diffusion reactions and a slow dissolution of copper. It appears from these results that the dissolution of copper is heavily influenced by diffusion phenomena and the corrosion product film porosity. Both techniques show good results for cleaning, as long as the proper parameters are used. These depend on the nature of the artefact and the corrosion layers that are found on its surface.

Green mitigation strategy for cultural heritage: bacterial potential for biocide production

Several biosurfactants with antagonistic activity are produced by a variety of microorganisms. Lipopeptides (LPPs) produced by some Bacillus strains, including surfactin, fengycin and iturin are synthesized nonribosomally by mega-peptide synthetase (NRPS) units and they are particularly relevant as antifungal agents. Characterisation, identification and evaluation of the potentials of several bacterial isolates were undertaken in order to establish the production of active lipopeptides against biodeteriogenic fungi from heritage assets. Analysis of the iturin operon revealed four open reading frames (ORFs) with the structural organisation of the peptide synthetases. Therefore, this work adopted a molecular procedure to access antifungal potential of LPP production by Bacillus strains in order to exploit the bioactive compounds synthesis as a green natural approach to be applied in biodegraded cultural heritage context. The results reveal that the bacterial strains with higher antifungal potential exhibit the same morphological and biochemical characteristics, belonging to the genera Bacillus. On the other hand, the higher iturinic genetic expression, for Bacillus sp. 3 and Bacillus sp. 4, is in accordance with the culture antifungal spectra. Accordingly, the adopted methodology combining antifungal screening and molecular data is represent a valuable tool for quick identification of iturin-producing strains, constituting an effective approach for confirming the selection of lipopeptides producer strains.

Toxicological assessment of novel green biocides for cultural heritage.

The damaging of buildings and monuments by biological contamination is a cause of serious concern. Biocides based on chemical toxic compounds have been used to mitigate this problem. However, in the past decade many of the most effective biocides have been banned due to their environmental and health hazards. Therefore, proper remediation actions for microbiologically contaminated historic materials based on environmentally safe solution is of vital importance. Bacillus species are emerging as a promising alternative for built heritage treatment. They produce a great diversity of secondary metabolites with biological activity, well known to possess antagonistic activities against many fungal pathogens. In order to evaluate the antifungal activity of the novel biocides produced in our laboratory by cultures of selected bacterial strains, liquid interaction assays using four biodeteriogenic fungi were achieved, revealing a nearly 100% of inhibitory capacity to fungal proliferation. To confirm their effective safe toxicological properties, in vivo tests using two different biological models were performed. The lyophilized supernatant of the Bacillus culture broth showed no lethality against brine shrimp and also no toxicological effects in Swiss mice through administration of acute dose of 5000 mg/kg by oral gavage. In fact, the bioactive compounds were no lethal at the tested dose unlike Preventol® (commercial biocide) that induced acute toxicity with 10 times minor concentration dose administrated in the same conditions. Therefore, the new bioactive compounds that suppress growth of biodeteriogenic fungi on historical artworks, presenting at the same time no toxicity against other living organisms, constituting an efficient and green safe solution for biodegradation/biodeterioration treatment of Cultural Heritage.

Combined Use of NMR, LC-ESIMS and Antifungal Tests for Rapid Detection of Bioactive Lipopeptides Produced by Bacillus

The science and technology interact with the art in several ways. Biotechnological coupled with analytical approaches can play an important role in protecting and preserving cultural heritage for future generations. Many microorganisms influenced by environmental conditions are the main responsible for biological contamination in built heritage. Biocides based on chemical compounds have been used to mitigate this problem. Thus, it is vitally important to develop proper remediation actions based on environmentally innocuous alternative. Bacillus specie is emerging as an optimistic alternative for built heritage treatment due to their capacity to produce secondary metabolites with antagonistic activities against many fungal pathogens. Therefore, the intent of this work was to access a rapid evaluation of antifungal potential of bioactive metabolites produced by Bacillus strains and simultaneously their characterization using spectroscopic (NMR) and chromatographic techniques (LCESI- MS). The high antifungal activity obtained for Bacillus sp. active compounds produced in this study confirms the great potential to suppress biodeteriogenic fungi growth on historical artworks. Additionally, the proposed methodology allowed to access bioactive metabolites produced without need of the laborious total previous isolation and could be used as a viable alternative to be employed for screening and production of new green biocides.

Urban public policies: towards the improvement of landscape ecological system. The case-study of the city of Évora, Portugal.

The Charter of European Planning 2013 presents a Vision for the future of European cities and regions, highlighting the sustainability of cities and the preservation of urban ecosystems, integrating the man-made environment with the natural ecosystems and contribute to the well-being and quality of life of their inhabitants and other stakeholders. Thus, urban public policies are crucial to the improvement of the landscape ecological system, achievable by city planning and design. The paper aims to analyse if public urban policies in Portugal have been integrating strategies and/or guidelines to enhance the ecological system of the landscape. Then, which new perspectives are possible, framed by the recently approved law Bases of Public Policy of Soils, Land Management and Urban Planning (2014). This new law, in contrast with the previous ones, don’t allow reserving land to urbanize, in municipal master plans. Moreover, it is possible to revert land classified for urban purposes in those plans into rustic soils (when it is not yet infra-structured or built). It allows creating new planning and design dynamics, convert several areas and including them in the urban ecological structure, essential to the enhancement of landscape ecological system. This is a filed of work where landscape architecture has huge responsibilities, by associating and harmonize man-made environment with natural systems, enlightening sustainability consistent with conservation and improvement of Nature while contributing to the well-being and quality of life of Man. A sustainability that is ethical, aesthetic, ecological and cultural. The study is supported by a case study – the city of Évora. The ultimate goal is to propose measures to promote larger and better integration of ecological component in urban public policies, framed by the new territorial management law, taking into account and highlighting the specificities of the landscape system – Man and Nature – at the local level.