Search results for "circular"
showing 10 items of 856 documents
The Influence of the Circular Economy: Exploring the Knowledge Base
2019
The objective of this study is to analyze the main factors influencing research on theconcept of &lsquo
Minimal Forbidden Factors of Circular Words
2017
Minimal forbidden factors are a useful tool for investigating properties of words and languages. Two factorial languages are distinct if and only if they have different (antifactorial) sets of minimal forbidden factors. There exist algorithms for computing the minimal forbidden factors of a word, as well as of a regular factorial language. Conversely, Crochemore et al.ÃÂ [IPL, 1998] gave an algorithm that, given the trie recognizing a finite antifactorial language M, computes a DFA of the language having M as set of minimal forbidden factors. In the same paper, they showed that the obtained DFA is minimal if the input trie recognizes the minimal forbidden factors of a single word. We gener…
Resveratrol-Related Dehydrodimers: Laccase-Mediated Biomimetic Synthesis and Antiproliferative Activity
2012
Seven resveratrol-related monomeric stilbenoids were submitted to biomimetic oxidative coupling in the presence of laccase from Trametes versicolor (TvL), and gave racemic dihydrobenzofuran dehydrodimers (±)-15 to (±)-21. These products, after spectral characterization, were submitted to an antiproliferative activity bioassay against SW480 human colon cancer cells. Five racemates were found to be active, and were resolved by chiral HPLC. The pure enantiomers were subjected to circular dichroism measurements to establish their absolute configurations at C-7 and C-8. These enantiomerically pure compounds were submitted to the antiproliferative activity assay towards SW480 cells, and were all …
Ethane-Bridged Zinc-Porphyrin Dimers in Langmuir-Shäfer Thin Films: Structural and Spectroscopic Properties
2006
This work reports on the structural and spectroscopic properties of ethane-bridged Zn porphyrin dimers (1) in Langmuir-Scha¨fer (LS) thin films by combining scanning force microscopy (SFM) with film balance, UV-vis absorption, fluorescence, and nanosecond laser flash photolysis measurements. Results show that depending on the surface pressure the Langmuir films of pure 1 can be arranged in two different condensed phases, whereas SFM of the LS films shows characteristic fractal networks constituted by nanoscopic aggregates. The spectral findings agree with a picture in which 1 is apparently present in the anti conformation but aggregated in a sort of H-type structure whose optical features r…
Influence of thermally induced structural transformations on the magnetic and luminescence properties of tartrate-based chiral lanthanide organic-fra…
2020
This work reports on the synthesis and characterization of five enantiomeric pairs of isostructural 3D metal-organic frameworks (MOFs) with the general formula {[Ln2(μ4-tar)2(μ-tar)(H2O)2]·xH2O}n [where Ln(iii) = Tb (Tb-L and Tb-D), Dy (Dy-L and Dy-D), Ho (Ho-L and Ho-D), Er (Er-L and Er-D) and Tm (Tm-L and Tm-D); tar = tartrate (d- or l-) and x = 3 or 4 depending on the counterpart], which possess interesting luminescence and magnetic properties. These MOFs undergo progressive and reversible dehydration processes upon controlled heating yielding three crystalline phases (Ln-L′, Ln-L′′ and Ln-L′′′). Alternating current magnetic measurements on Tb, Dy and Er-based compounds exhibit field ind…
Coffee biowaste valorization within circular economy: an evaluation method of spent coffee grounds potentials for mortar production
2021
Abstract Purpose Spent coffee grounds (SCG) are biowastes extensively generated within the coffee supply chain. Nowadays, their disposal represents an increasing environmental concern due to its toxicity and organic nature. With the estimated increase of coffee production and consumption in the upcoming years, there is an imperative need to find a proper reverse option, along with a novel industrial application, which allows for the valorization of this coffee by-product within a circular economy perspective. This study aims at investigating a potential reuse of spent coffee grounds to produce novel construction materials to be used for sustainable buildings. Methods After having illustrate…
Environmental assessment of a waste-to-energy practice: The pyrolysis of agro-industrial biomass residues
2021
Abstract The bio-wastes pyrolysis is a waste to energy strategy that converts bio-wastes into valuable products (bio-char, bio-oil) with wide use in the agri-food sector. However, limited efforts are paid to the investigation of its environmental sustainability: in this context, the study contributes the need towards the assessment of a wide range of environmental impacts for the pyrolysis process of different types of bio-wastes under different operating conditions. The study estimates the potential environmental impacts related to bio-char production from the pyrolysis of several different agro-industrial residues and different temperatures and identifies the process “hot spots”. The anal…
Magnetic ordering in an (Fe0.2Cr0.8)1.5[Cr(CN)6] Prussian blue analogue studied with synchrotron radiation based spectroscopies
2018
The appearance of magnetic order in the (Fe0.2Cr0.8)1.5[Cr(CN)6]·15H2O Prussian blue analogue at low temperature has been investigated by means of synchrotron radiation-based X-ray absorption spectroscopy and X-ray magnetic circular dichroism. With the help of ligand field multiplet analysis we have been able to identify the oxidation states of the metallic cations present in the sample and their evolution with temperature. Our experiments reveal that the appearance of ferromagnetic order is triggered by the transformation of CrIII cations to CrII high-spin caused by a transfer of electrons from the Fe to the Cr resulting in an increase of the magnetic interactions within the (Cr, Cr) subla…
Characterization of the nucleation process of lysozyme at physiological pH: Primary but not sole process
2013
We report on a kinetic study of the heat-induced aggregation process of lysozyme at physiological pH. The time evolution of the aggregation extent and the conformational changes of the protein were followed by dynamic light scattering (DLS) and FTIR spectroscopy, respectively, whereas the morphology of the aggregates was observed by Atomic Force Microscopy (AFM). The conformational changes of the secondary and tertiary structures were simultaneous and distinct in time with respect to the formation of aggregates. Oligomer formation occurred through at least two different aggregation processes: a nucleation process and a homogeneous non-nucleative diffusion-controlled process. FTIR measuremen…
Predictive First-Principles Modeling of a Photosynthetic Antenna Protein: The Fenna–Matthews–Olson Complex
2020
High efficiency of light harvesting in photosynthetic pigment–protein complexes is governed by evolutionary-perfected protein-assisted tuning of individual pigment properties and interpigment interactions. Due to the large number of spectrally overlapping pigments in a typical photosynthetic complex, experimental methods often fail to unambiguously identify individual chromophore properties. Here, we report a first-principles-based modeling protocol capable of predicting properties of pigments in protein environment to a high precision. The technique was applied to successfully uncover electronic properties of the Fenna–Matthews–Olson (FMO) pigment–protein complex. Each of the three subunit…