Search results for "Ordination"
showing 10 items of 1367 documents
An automated procedure for computing the packing properties of dense and locked sands by image analysis of thin sections
2014
The macroscopic mechanical behaviour of dense sands originates to a great extent from their microstructural characteristics such as the coordination number, the grain contact and the packing density indexes. The study of intergranular contacts and the reckoning of these indexes may be carried out on planar images of the grains either by means of time-consuming visual inspection assisted by CAD or by automatic image analysis. An innovative method for the automatic determination of microstructural characteristics of sands based on image analysis of thin section is proposed. Tests performed on a locked sand show that the proposed method is much more effective, convenient and faster than the us…
Enhancement of guest-responsivity by mesocrystallization of porous coordination polymers
2017
Mesocrystals of a porous coordination polymer {Fe(pz)[Pt(CN)4]} (1) showing spin transition were prepared by the reverse micelle method, and the size-controlled mesocrystal 1 kept its porous property and magnetic bistability and exhibited higher guest-responsivity with switching the spin state in both solid and aqueous suspension states than the bulk 1.
Design of Bistable Gold@Spin‐Crossover Core–Shell Nanoparticles Showing Large Electrical Responses for the Spin Switching
2019
<p>A simple protocol to prepare core-shell gold@spin-crossover (Au@SCO) nanoparticles (NPs) based on the 1D spin-crossover [Fe(Htrz)<sub>2</sub>(trz)](BF<sub>4</sub>) coordination polymer is reported. The synthesis relies on a two-step approach consisting on a partial surface ligand substitution of the citrate-stabilized Au NPs followed by the controlled growth of a very thin layer of the SCO polymer. As a result, colloidally stable core@shell spherical NPs of 19 nm in size exhibiting a narrow distribution in sizes have been obtained, revealing a switchable SCOshell of <i>ca.</i>4 nm. Temperature-dependent charge transport measurements of an electri…
Guest induced reversible on–off switching of elastic frustration in a 3D spin crossover coordination polymer with room temperature hysteretic behavio…
2021
A binary reversible switch between low-temperature multi-step spin crossover (SCO), through the evolution of the population γHS(T) with high-spin (HS)-low-spin (LS) sequence: HS1LS0 (state 1) ↔ HS2/3LS1/3 (state 2) ↔ HS1/2LS1/2 (state 3) ↔ HS1/3LS2/3 (state 4) ↔ HS0LS1 (state 5), and complete one step hysteretic spin transition featuring 20 K wide thermal hysteresis centred at 290 K occurs in the three-dimensional (3D) Hofmann-type porous coordination polymer {FeII(3,8phen)[Au(CN)2]2}·xPhNO2 (3,8phen = 3,8-phenanthroline, PhNO2 = nitrobenzene), made up of two identical interpenetrated pcu-type frameworks. The included PhNO2 guest (x = 1, 1·PhNO2) acts as a molecular wedge between the interp…
Pressure effect investigations on spin-crossover coordination compounds
2018
International audience; The piezochromic properties of spin-crossover complexes have been recognized for a long time, with increasing pressure favouring the low spin state due to its smaller volume and therefore shifting the spin equilibrium towards higher temperatures and accelerating the relaxation at a given temperature. However, the interpretation and quantification of pressure-induced changes have been several times compromised by the relatively poor and incomplete spectral and structural information provided by the detection methods or due to the experimental difficulties related to the need for hydrostatic conditions at low temperatures. The present review is therefore primarily focu…
Spin Crossover Metal-Organic Frameworks with Inserted Photoactive Guests: On the Quest to Control the Spin State by Photoisomerization
2021
International audience; Three Hofmann-like metal-organic frameworks {Fe(bpac)[Pt(CN)4]}•G (bpac=1,2-bis(4-pyridyl)acetylene) were synthesized with photoisomerizable guest molecules (G = trans-azobenzene, trans-stilbene or cis-stilbene) and were characterized by elemental analysis, thermogravimetry and powder X-ray diffraction. The insertion of guest molecules and their conformation were inferred from Raman and FTIR spectra and from single-crystal X-ray diffraction and confronted with computational simulation. The magnetic and photomagnetic behaviors of the framework are significantly altered by the different guest molecules and different conformations. On the other hand, photoisomerization …
Scheduling Multimodal Transportation Systems
2004
Abstract In this paper a Lagrangian based heuristic procedure for scheduling transportation networks is presented. The solution procedure schedules a single line at a time, possibly correcting the previous decisions at each step.
Self-assembly of catalytically-active supramolecular coordination compounds within metal-organic frameworks
2019
[EN] Supramolecular coordination compounds (SCCs) represent the power of coordination chemistry methodologies to self-assemble discrete architectures with targeted properties. SCCs are generally synthesized in solution, with isolated fully coordinated metal atoms as structural nodes, thus severely limited as metal-based catalysts. Metal-organic frameworks (MOFs) show unique features to act as chemical nanoreactors for the in situ synthesis and stabilization of otherwise not accessible functional species. Here, we present the self-assembly of Pd-II SCCs within the confined space of a pre-formed MOF (SCCs@MOF) and its post-assembly metalation to give a Pd-II-Au-III supra molecular assembly, c…
Spatial structure of helminth communities in the golden grey mullet, Liza aurata (Actinopterygii: Mugilidae), from the Western Mediterranean.
2012
Ecological investigations regarding the parasite fauna of grey mullets are scarce. The present study provides a detailed description of the helminth communities of Liza aurata in the Spanish western Mediterranean and analyzes the role of spatial, temporal, and host variables in shaping the infracommunities. In total, 204 fish were collected in 2 localities, situated ca. 290 km apart, in spring and fall of 2004 and 2005. A non-metric multidimensional scaling (NMDS) was used to visualize an ordination of the infracommunities according to their relative similarities in parasite abundances. The relationship between infracommunity composition and explanatory variables (host size, locality, year,…
Loss of Ostracoda biodiversity in Western Mediterranean wetlands
2008
1. The coastal area of Valencia (Spain) in the Western Mediterranean is rich in freshwater and brackish wetlands. These areas are mostly protected for bird conservation but are also highly affected by human impacts. Six shallow lakes located in Ramsar wetland sites of this area were studied in order to assess past and present ostracod biodiversity and relate it to the status of the lakes, taking into consideration the indicator value of these easily fossilizable crustaceans. 2. In all the wetlands studied, ostracod taphocoenoses showed much higher species richness than the corresponding biocoenoses. This is expected from the time accumulative character of the taphocoenosis, but the trend is…