Caught in the Act:Mechanistic Insight into Supramolecular Polymerization-Driven Self-Replication from Real-Time Visualization

Self-assembly features prominently in fields ranging from materials science to biophysical chemistry. Assembly pathways, often passing through transient intermediates, can control the outcome of assembly processes. Yet, the mechanisms of self-assembly remain largely obscure due to a lack of experimental tools for probing these pathways at the molecular level. Here, the self-assembly of self-replicators into fibers is visualized in real-time by high-speed atomic force microscopy (HS-AFM). Fiber growth requires the conversion of precursor molecules into six-membered macrocycles, which constitute the fibers. HS-AFM experiments, supported by molecular dynamics simulations, revealed that aggregates of precursor molecules accumulate at the sides of the fibers, which then diffuse to the fiber ends where growth takes place. This mechanism of precursor reservoir formation, followed by one-dimensional diffusion, which guides the precursor molecules to the sites of growth, reduces the entropic penalty associated with colocalizing precursors and growth sites and constitutes a new mechanism for supramolecular polymerization

urban sustainable development in the mediterranean area the case of sestri ponente genoa

In November 2014 a green facade was built in the Sestri Ponente district in Genoa, Italy, on an office building owned by the Istituto Nazionale di Previdenza Sociale (National Institute of Social Insurance). This area, which is characterized by a relatively high population density, faces important environmental issues related to, for example, air pollution, stormwater management, and the urban heat island effect. The Department of Sciences for Architecture at the University of Genoa (Italy) is conducting monitoring activity to evaluate the effectiveness of the green facade with regard to summer cooling, winter heating – in collaboration with Research on the Energy System – air quality improvement, and economic and environmental sustainability. Starting from this first pilot project a question arises: what would be the effect of vegetation at the district scale? This article discusses the potentialities for urban sustainable development of the integration of green infrastructure. Simulations carried out with ENVI-Met software demonstrate the potentialities of different amounts of vegetation for urban heat island mitigation. In addition, the possible stormwater runoff reduction was calculated. Such calculations are based on urban design projects developed for the area to evaluate the possible improvement to environmental quality owing to the integration of green infrastructure

The green building envelope: Vertical greening

Planting on roofs and façades is one of the most innovative and fastest developing fields of green technologies with respect to the built environment and horticulture. This thesis is focused on vertical greening of structures and to the multi-scale benefits of vegetation. Vertical green can improve the environment in urban areas and is becoming a key design consideration in modern building developments. Vertical greening of structures offers large surfaces with vegetation and at the same time contribute to the improvement of the thermal behaviour of buildings, increased biodiversity, aesthetical and social aspects but also reduction of air polluting substances as fine dust, carbon dioxide, etc. There are different concepts of vertical green to vegetate the exterior building envelope; two major categories can be considered namely: green façades and living walls. Green façades are made up of climbing plants either growing directly on a wall or, more recently, growing indirectly against a wall with specially designed supporting structures, such as grids, trellis or meshes. Living wall systems (LWS) are composed of pre-vegetated panels or integrated fabric systems that are affixed to a structural wall or frame, whereas a hydroponical system is required to maintain plant growth. Living wall systems (LWS) is a relative new technology and rarely investigated yet. One of the multi-scale benefits of vegetation is the accumulation of fine dust particles on leaf surfaces. Dust particles smaller than 10 ?m are mainly relevant in dense urban areas, because they can be deeply inhaled into the respiratory system and cause damages for the human health. Results found during the doctoral study confirm the relation between particle origin, compound and particle number between different environments as the woodland and near a traffic road. Using image analyzing software on electron microscope images as shown in the thesis enables to study and examine dust particles directly on leaves; it is a process which is able to identify particle size and number. The productive approach contrasts with past research methods that identified dust concentration on tree leaves through washing or leaching of leaves to determine particle mass. Another important aspect of vertical greening is related to the thermal comfort and behaviour of buildings. The thermal transmittance (and thus insulation properties as well) of a building is among other things dependant by the wind velocity that passes the surface of the building. A study conducted for different greening systems shows the potential of vertical green layers on reducing the wind velocity along building façades. In the case of living wall systems the insulation properties of the materials used can be taken into account, as well as the air cavity between the system and the façade as proofed with the calculations. In order to study the effect of a green layer on the temperature gradient through a façade better, an experimental set-up was built (climate chambers). The experimental set-up as used, allows controlled measurements with different boundary conditions (temperatures), besides the measurements are repeatable and reproducible. The results show that especially the living wall systems have a positive effect on the thermal behaviour of buildings. Greening of the building envelope with living wall systems considering the materials involved, can has a high influence on the environmental profile (life cycle analysis) as shown in the thesis. Although applying vertical green is not a new concept, it can offer multiple benefits as a component of current urban design. Considering the relation between the environmental benefits, energy saving for the building and the vertical greening systems (material used, maintenance, nutrients and water needed) the integration of vegetation could be a sustainable approach (taking into account all the unquantifiable benefits until now) for the envelope of new and existing buildings.Materials & Environment chair SustainabilityCivil Engineering and Geoscience

Vertical greening systems: contribution to thermal behaviour on the building envelope and environmental sustainability

none2Contemporary architecture is increasingly focusing on vertical greening systems as a means to restore the environmental integrity of urban areas and sustainability. Despite the interest demonstrated by the European market and the international research on this topic, vertical greening systems are not yet fully accepted as an energy saving method for the built environment. This paper provides a perspective on vertical greening systems with respect to the possible improvement of the building envelope efficiency in the field of environmental sustainability. The several systems available on the market have different characteristics (layers involved, plant species, maintenance needs, etc.), which influence the cooling potential and the insulation properties besides their aesthetic effect, functional aspects, and the environmental burden produced during the their life span. The analysis of the different characteristics, advantages and critical aspects of vertical greening systems considers the complexity of these systems and the potential improvement of building envelope efficiency brought by vertical gardens.openK. Perini; M. OtteléPerini, Katia; M., Ottel

Vertical greening systems, a process tree for green façades and living walls

none4This study shows that greening the building envelope with vertical greening systems such as climbing plants or living wall systems provides ecological and environmental benefits. Contemporary architecture in fact is increasingly focusing on vertical greening systems as a means to restore the environmental integrity of urban areas, biodiversity and sustainability. Applying green façades, which is an established feature of contemporary urban design, can offer multiple environmental benefits on both new and existing buildings and can be a sustainable approach in terms of energy saving considering materials used, nutrients and water needed and efficient preservation of edifices. To provide a full perspective and a viable case study on vertical greening systems a process tree is developed throughout this research. Elaborating the process tree has proved to be a useful methodology to analyse main parameters as climate and building characteristics, avoid damages and maintenance problems caused by inappropriate design, and compare different elements such as technologies, materials, durability, dimensions, and plant species employed.Citazioni in data 27 marzo 2017: Google Scholar: 39, Scopus: 22mixedK. Perini; M. Ottelé;E. M. Haas; R. RaiteriPerini, Katia; M., Ottelé; E. M., Haas; Raiteri, Rossan

Generalist versus Specialist Self-Replicators

Darwinian evolution, including the selection of the fittest species under given environmental conditions, is a major milestone in the development of synthetic living systems. In this regard, generalist or specialist behavior (the ability to replicate in a broader or narrower, more specific food environment) are of importance. Here we demonstrate generalist and specialist behavior in dynamic combinatorial libraries composed of a peptide-based and an oligo(ethylene glycol) based building block. Three different sets of macrocyclic replicators could be distinguished based on their supramolecular organization: two prepared from a single building block as well as one prepared from an equimolar mixture of them. Peptide-containing hexamer replicators were found to be generalists, i.e. they could replicate in a broad range of food niches, whereas the octamer peptide-based replicator and hexameric ethyleneoxide-based replicator were proven to be specialists, i.e. they only replicate in very specific food niches that correspond to their composition. However, sequence specificity cannot be demonstrated for either of the generalist replicators. The generalist versus specialist nature of these replicators was linked to their supramolecular organization. Assembly modes that accommodate structurally different building blocks lead to generalist replicators, while assembly modes that are more restrictive yield specialist replicators.</p

Generalist versus Specialist Self-Replicators

Darwinian evolution, including the selection of the fittest species under given environmental conditions, is a major milestone in the development of synthetic living systems. In this regard, generalist or specialist behavior (the ability to replicate in a broader or narrower, more specific food environment) are of importance. Here we demonstrate generalist and specialist behavior in dynamic combinatorial libraries composed of a peptide-based and an oligo(ethylene glycol) based building block. Three different sets of macrocyclic replicators could be distinguished based on their supramolecular organization: two prepared from a single building block as well as one prepared from an equimolar mixture of them. Peptide-containing hexamer replicators were found to be generalists, i.e. they could replicate in a broad range of food niches, whereas the octamer peptide-based replicator and hexameric ethyleneoxide-based replicator were proven to be specialists, i.e. they only replicate in very specific food niches that correspond to their composition. However, sequence specificity cannot be demonstrated for either of the generalist replicators. The generalist versus specialist nature of these replicators was linked to their supramolecular organization. Assembly modes that accommodate structurally different building blocks lead to generalist replicators, while assembly modes that are more restrictive yield specialist replicators.</p

Generalist versus Specialist Self-Replicators

Darwinian evolution, including the selection of the fittest species under given environmental conditions, is a major milestone in the development of synthetic living systems. In this regard, generalist or specialist behavior (the ability to replicate in a broader or narrower, more specific food environment) are of importance. Here we demonstrate generalist and specialist behavior in dynamic combinatorial libraries composed of a peptide-based and an oligo(ethylene glycol) based building block. Three different sets of macrocyclic replicators could be distinguished based on their supramolecular organization: two prepared from a single building block as well as one prepared from an equimolar mixture of them. Peptide-containing hexamer replicators were found to be generalists, i.e. they could replicate in a broad range of food niches, whereas the octamer peptide-based replicator and hexameric ethyleneoxide-based replicator were proven to be specialists, i.e. they only replicate in very specific food niches that correspond to their composition. However, sequence specificity cannot be demonstrated for either of the generalist replicators. The generalist versus specialist nature of these replicators was linked to their supramolecular organization. Assembly modes that accommodate structurally different building blocks lead to generalist replicators, while assembly modes that are more restrictive yield specialist replicators.</p

Air cleaning performance of two species of potted plants and different substrates

Potted plants have been reported to uptake VOCs and help “cleaning” the air. This paper presents the results of a laboratory study in which two species of plants (peace lily and Boston fern) and three kinds of substrates (expanded clay, soil, and activated carbon) were tested and monitored on their capacity to deplete formaldehyde and CO2 in a glass chamber. Formaldehyde and CO2 were selected as indicators to evaluate the biofiltration efficacy of 28 different test conditions; relative humidity (RH) and temperature (T) were monitored during the experiments. To evaluate the efficacy of every test, the clean air delivery rate (CADR) was calculated. Overall, soil had the best performance in removing formaldehyde (~0.07–0.16 m3/h), while plants, in particular, were more effective in reducing CO2 concentrations (peace lily 0.01m3/h) (Boston fern 0.02–0.03 m3/h). On average, plants (~0.03 m3/h) were as effective as dry expanded clay (0.02–0.04 m3/h) in depleting formaldehyde from the chamber. Regarding air-cleaning performance, Boston ferns presented the best performance among the plant species, and the best performing substrate was the soil