Textural Characterization of Micro- and Mesoporous Carbons Using Combined Gas Adsorption and n-Nonane Preadsorption

Porous carbon and carbide materials with different structures were characterized using adsorption of nitrogen at 77.4 K before and after preadsorption of n-nonane. The selective blocking of the microporosity with n-nonane shows that ordered mesoporous silicon carbide material (OM-SiC) is almost exclusively mesoporous whereas the ordered mesoporous carbon CMK-3 contains a significant amount of micropores (25%). The insertion of micropores into OM-SiC using selective extraction of silicon by hot chlorine gas leads to the formation of ordered mesoporous carbide-derived carbon (OM-CDC) with a hierarchical pore structure and significantly higher micropore volume as compared to CMK-3, whereas a CDC material from a nonporous precursor is exclusively microporous. Volumes of narrow micropores, calculated by adsorption of carbon dioxide at 273 K, are in linear correlation with the volumes blocked by n-nonane. Argon adsorption measurements at 87.3 K allow for precise and reliable calculation of the pore size distribution of the materials using density functional theory (DFT) methods.

Beta diversity at multiple hierarchical levels: explaining the high diversity of scarab beetles in tropical montane forests

Aim: High gamma diversity in tropical montane forests may be ascribed to high geographical turnover of community composition, resulting from population isolation that leads to speciation. We studied the evolutionary processes responsible for diversity and turnover in assemblages of tropical scarab beetles (Scarabaeidae) by assessing DNA sequence variation at multiple hierarchical levels. Location: A 300-km transect across six montane forests (900–1100 m) in Costa Rica. Methods: Assemblages of Scarabaeidae (subfamilies Dynastinae, Rutelinae, Melolonthinae) including 118 morphospecies and > 500 individuals were sequenced for the cox1 gene to establish species limits with a mixed Yule–coalescent method. A species-level phylogenetic tree was constructed from cox1 and rrnL genes. Total diversity and turnover among assemblages were then assessed at three hierarchical levels: haplotypes, species and higher clades. Results: DNA-based analyses showed high turnover among communities at all hierarchical levels. Turnover was highest at the haplotype level (community similarity 0.02–0.12) and decreased with each step of the hierarchy (species: 0.21–0.46; clades: 0.41–0.43). Both compositional and phylogenetic similarities of communities were geographically structured, but turnover was not correlated with distance among forests. When three major clades were investigated separately, communities of Dynastinae showed consistently higher alpha diversity, larger species ranges and lower turnover than Rutelinae and Melolonthinae. Main conclusions: Scarab communities of montane forests show evidence of evolutionary persistence of communities in relative isolation, presumably tracking suitable habitats elevationally to accommodate climatic changes. Patterns of diversity on all hierarchical levels seem to be determined by restricted dispersal, and differences in Dynastinae could be explained by their greater dispersal ability. Community-wide DNA sequencing across multiple lineages and hierarchical levels reveals the evolutionary processes that led to high beta diversity in tropical montane forests through time.

Breaking down complex saproxylic communities: understanding sub-networks structure and implications to network robustness

Saproxylic insect communities inhabiting tree hollow microhabitats correspond with large food webs which simultaneously are constituted by multiple types of plant-animal and animal-animal interactions, according to the use of trophic resources (wood- and insect-dependent sub-networks), or to trophic habits or interaction types (xylophagous, saprophagous, xylomycetophagous, predators and commensals). We quantitatively assessed which properties of specialised networks were present in a complex networks involving different interacting types such as saproxylic community, and how they can be organised in trophic food webs. The architecture, interacting patterns and food web composition were evaluated along sub-networks, analysing their implications to network robustness from random and directed extinction simulations. A structure of large and cohesive modules with weakly connected nodes was observed throughout saproxylic sub-networks, composing the main food webs constituting this community. Insect-dependent sub-networks were more modular than wood-dependent sub-networks. Wood-dependent sub-networks presented higher species degree, connectance, links, linkage density, interaction strength, and were less specialised and more aggregated than insect-dependent sub-networks. These attributes defined high network robustness in wood-dependent sub-networks. Finally, our results emphasise the relevance of modularity, differences among interacting types and interrelations among them in modelling the structure of saproxylic communities and in determining their stability.

Synthesis of Robust Hierarchical Silica Monoliths by Surface-Mediated Solution/Precipitation Reactions over Different Scales: Designing Capillary Microreactors for Environmental Applications

A synthetic procedure to prepare novel materials (surface-mediated fillings) based on robust hierarchical monoliths is reported. The methodology includes the deposition of a (micro- or mesoporous) silica thin film on the support followed by growth of a porous monolithic SiO2 structure. It has been demonstrated that this synthesis is viable for supports of different chemical nature with different inner diameters without shrinkage of the silica filling. The formation mechanism of the surface-mediated fillings is based on a solution/precipitation process and the anchoring of the silica filling to the deposited thin film. The interaction between the two SiO2 structures (monolith and thin film) depends on the porosity of the thin film and yields composite materials with different mechanical stability. By this procedure, capillary microreactors have been prepared and have been proved to be highly active and selective in the total and preferential oxidation of carbon monoxide (TOxCO and PrOxCO).

Influence of tree hollow characteristics on the diversity of saproxylic insect guilds in Iberian Mediterranean woodlands

Saproxylic diversity assessment is a major goal for conservation strategies in woodlands and it should consider woodland composition and configuration at site and tree level as key modelling factors. However, in Mediterranean woodlands little is known about the relation with the environmental factors that structure their assemblages, especially those linked to tree hollow microhabitats. We assessed the diversity of Syrphidae (Diptera) and Coleoptera saproxylic guilds that co-occurred in tree hollows located in three different Iberian Mediterranean woodlands in the Cabañeros National Park (Spain). Furthermore, we evaluated how differences in tree hollow microenvironmental variables (understood as the physical and biotic characteristics of a hollow and tree individual) influenced saproxylic guild diversity both within and among woodland sites. We found that woodland sites that provided greater heterogeneity of trees and hollow microhabitats determined higher saproxylic guild diversity. Nevertheless, certain species or even complete guilds can be favoured in woodlands where some hollow microhabitats predominate as a consequence of historical tree management. In general, hollow volume was the main determining factor for saproxylic guild richness and abundance in woodland sites, and large hollow volume was usually related to higher diversity, which highlighted the importance of multi-habitat hollow trees. Moreover, saproxylic guilds also responded to other different microenvironmental variables, which indicated different ecological preferences among guilds. The conservation of saproxylic insects in Iberian Mediterranean areas must be addressed to protect woodland sites that provide high diversity and large numbers of tree hollow microhabitats, and practices to enhance microhabitat heterogeneity should even be encouraged.

Steel Pedestrian Bridge to Protect a Unique Tree

This paper describes the “Variation Guggenheim 3: Mirador de la palmera” project, situated in Daya Vieja (Alicante-Spain). This structure is inspired by the Guggenheim museum of New York and is designed to protect a land-mark palm-tree from wind loads. This six – trunk palm tree was declared monument by the Valencian government in 2012. The structure that now protect it appears to fly around de palm tree creating a helicoidally skywalk made of steel, while retrofitting the lateral trunks of the tree to protect them from collapse. An 18 m. long straight beam starts on the top of this helix, and stretches towards a lookout point that offers a view of the whole village and its surroundings. The reduction of the visual impact of the structure on the tree was a major aim for the project design. The structural elements are as slender as possible to avoid the visual obstruction of tree. They are painted white, while the walkway steel corrugated plate is painted green in order to highlight its neat shape among the blur created by the apparent mess of bars of the supporting structure. The two main piles of this pedestrian bridge were designed in steel and geometrically resemble trees. A Ground Penetrating Radar analysis was performed to detect the palm root location and to decide the best foundation system. Slender cast in-situ steel-concrete micropiles along with a concrete pile-cap, raised some centimeters above the ground level, were used to reduce the damage to the roots. The projected pile-cap is a slender, continuous, circular ring; which geometry resembles a concrete bench. This structure has been a finalist in the Architecture Awards for the 2010-2014 best construction projects, held by the Diputación de Alicante.

What can physical, biotic and chemical features of a tree hollow tell us about their associated diversity?

Tree hollows are keystone structures for saproxylic fauna and host numerous endangered species. However, not all tree hollows are equal. Many variables including physical, biotic and chemical ones, can characterise a tree hollow, however, the information that these could provide about the saproxylic diversity they harbour has been poorly explored. We studied the beetle assemblages of 111 Quercus species tree hollows in four protected areas of the Iberian Peninsula. Three physical variables related to tree hollow structure, and two biotic ones (presence of Cetoniidae and Cerambyx species recognised as ecosystem engineers) were measured in each hollow to explore their relative effect on beetle assemblages. Moreover, we analysed the chemical composition of the wood mould in 34 of the hollows, in order to relate beetle diversity with hollow quality. All the environmental variables analysed (physical and biological) showed a significant influence on saproxylic beetle assemblages that varied depending on the species. Furthermore, the presence of ecosystem engineers affected both physical and chemical features. Although wood mould volume, and both biotic variables could act as beetle diversity surrogate, we enhance the presence of Cetoniidae and Cerambyx activity (both easily observable in the field) as indicator variables, even more if both co-occur as each affect to different assemblages. Finally, assimilable carbon and phosphorous contents could act as indicator for past and present beetle activity inside the cavity that could become a useful tool in functional diversity studies. However, an extension of this work to other taxonomic groups would be desirable.