1,720,993 research outputs found
Tris(2-pyridylmethyl)amines as emerging scaffold in supramolecular chemistry
No full texttris-(2-Pyridylmethyl)amine (usually abbreviated as TPA or TPMA) are ligands which are emerging in many fields of chemistry because of their ability to form stable and catalytically active complexes with a wide variety of metals. While the applications in catalysis began soon after the synthesis of the first metal complexes, studies in supramolecular chemistry are more recent and they often take advantage from their stereodynamic nature. This review surveys TPMA applications as: i) anion sensors, ii) biochemical sensors, iii) molecular switches, iv) chiral probes and as v) building blocks in the synthesis of supramolecular cages
Extending substrate sensing capabilities of zinc tris(2-pyridylmethyl)amine-based stereodynamic probe
No full textTripodal metal complexes have been widely used for catalysis and more recently also for molecular recognition applications. Their ability in recognition and signal amplification of chiral substrates is because of the setup of the ligand around the metal in a propeller shape. Within this subject, we have recently reported tris(2-pyridylmethyl)amine- and triphenolamine-based complexes for the determination of the enantiomeric excess of various substrates. Herein, we show the versatility of the zinc tris(2-pyridylmethyl)amine-based stereodynamic probe by performing a detailed study of the imine formation process, by the extension of the sensing capabilities to other chiral compounds. A principal component analysis study of the system together with TD-DFT studies highlights the molecular origin of the observed chiroptical properties
Calcium aluminate cement as an alternative to ordinary Portland cement for the remediation of heavy metals contaminated soil: mechanisms and performance
Full text linkPurpose: This work deals with the application of a solidification/stabilization process with the aim to obtain safe and reusable granular materials from a polluted soil and to elucidate the mechanisms involved in the retention of several heavy metals. Materials and methods: The High Performance Solidification/Stabilization (HPSS®) process was applied to the selected contaminated soil by using both ordinary Portland cement and calcium aluminate cement, as well as several binders prepared by combining these two types of cement in different proportions. Leaching and mechanical tests were carried out to evaluate the performances of the proposed binders in the pellets produced by the HPSS® process, while XRD analysis and SEM/EDX imaging were used to investigate the phase composition and internal microstructure of the treated samples. Result and discussion: The examination of the obtained granular materials revealed that the immobilization of Sb was mainly related to its inclusion within calcium silicate hydrates’ structure; the immobilization of Cr, Pb, Ni, Co, Zn and Tl was associated with the eluate pH and their incorporation within ettringite structure, while for Se, Cu, Ba and V, the main retention mechanism was physical encapsulation. In addition, the application of a wet conditioning process improved the materials’ performance, leading to granules always satisfying the Italian regulatory requirements for reuse. Conclusions: The findings obtained in this study were useful to better elucidate the mechanisms involved in the retention of heavy metals by several binders, contributing to the development of sustainable management strategies for contaminated soils and sediments through their transformation into reusable materials. Graphical abstract: [Figure not available: see fulltext.
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Screening sustainability assessment of innovative bio-based solutions for art restoration within the EC SSbD framework
Full text linkImplementing the EC Safe and Sustainable by Design (SSbD) framework from the early design phase of innovative solutions remains challenging. Although various methods to evaluate safety and sustainability exist, their integration throughout the innovation process, especially during the early stages at low Technology Readiness Levels (TRLs), is often hindered by time constraints, limited resources, the need for multidisciplinary expertise, and uncertainty in data availability and quality.
This study presents the Screening Sustainability Assessment (SSA), a screening-level method developed to support early-stage innovation by integrating functionality, safety, and sustainability aspects in product design. The SSA combines semi-quantitative scoring with targeted SSbD-oriented questions, enabling structured assessment across all life cycle stages. Each aspect is evaluated through specific criteria and questions, scored on a five-level scale, fostering informed stakeholder dialogue and supporting the early integration of SSbD objectives. The SSA was applied to assess two innovative bio-based protective coatings against a fossil-based benchmark. These products are intended for the preventive and remedial conservation of cultural heritage surfaces, a sector where traditional materials often present limitations in terms of durability, and sustainability performance. The application of the SSA method to the case study demonstrates its effectiveness in identifying SSbD performance and critical areas for improvement throughout the product life cycle. Although designed for the cultural heritage sector, the methodology is transferable to other fields facing similar challenges. It contributes to the broader goal of operationalizing the SSbD framework by offering a tool for embedding safety and sustainability considerations into innovation processes from the outset
A methodology to assess a mobile urban street cleaning activity
Full text linkAn experimental methodology to assess the human exposure of a street cleaning service, performed by a worker handling a leaf blower followed by a water-flushing sweeper, was developed. The sampling campaign was achieved by considering data from road dust, personal air sampling and portable particulate matter detector. The experimental design allowed to obtain qualitative and quantitative information on the chemical composition of road dust, the size and chemical composition of potentially inhalable particles suspended during the street cleaning activity, as well as the duration of the particles' suspension effect. The methodology employed showed: i) the compliance with the occupational exposure threshold values for the total inhalable dust and with the occupational exposure limit values according to national and international regulatory approaches for polycyclic aromatic hydrocarbons (PAH) and inorganic elements; ii) a good agreement of the metals concentrations from the road dust (i.e., calcium, magnesium, potassium, iron, aluminium and sodium) with those from the material collected by the personal air sampler, highlighting the negligible effect of the investigated sweeping activity compared to the material already present on the road; iii) a similar pattern of inorganic elements within the three different monitoring areas; iv) a “dust wave” effect detected by the particle counter lasting no more than 2 min. Thus, such information suggested that performing the urban sweeping activity in the early mornings, when there is a general low PM10-PM2.5 average concentration, low traffic intensity, and the almost absence of passers-by, lead to a low probability of citizens’ exposure
Consecutive thermal and wet conditioning treatments of sedimentary stabilized cementitious materials from HPSS® technology: Effects on leaching and microstructure
Full text linkSoil and sediment contamination is recognised as one of the most relevant environmental problems caused by past industrial activities and unsustainable waste disposal practices, highlighting the need to develop or improve effective remediation techniques to support sustainable management strategies. In this context, the remediation of sediments dredged from the Mincio river (Italy) contaminated by mercury and heavy hydrocarbons (C12-40) was carried out by applying and implementing the High Performance Solidification/Stabilization technology, aimed at producing safe and reusable cement-based granular materials. The technology was improved by decreasing both the temperature and time of the thermal desorption treatment (from 280 to 110 °C and from 4-16 h to 70 min, respectively) and by including a wet conditioning step to the process. Temperature and time reduction allowed to diminish the degradation of the cementitious phases of the granules (usually related to the high temperatures employed in the process), while the wet conditioning step allowed to improve their mechanical properties, as well as to further reduce the leaching of contaminants. The physical-chemical properties of the granules and contaminant leaching in water were investigated by Inductively Coupled Plasma Mass and Optical Emission Spectrometry, Ultraviolet–Visible spectroscopy, Gas Chromatography, X-Ray Powder Diffraction, and Scanning Electron Microscopy, in order to identify the optimal parameters for both thermal and wet conditioning processes. The overall results showed that the use of consecutive thermal and wet conditioning treatment on sedimentary cementitious materials from the High Performance Solidification/Stabilization technology led to the removal of volatile pollutants and to the improvement of granule quality, thus providing a final material that satisfied all the Italian regulatory requirements for reuse. Therefore, the findings obtained in this study may contribute to the development of sustainable management strategies for contaminated soils and sediments, leading to their valorisation through the transformation into reusable materials
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Supporting the development of sustainable nano-based formulations for the restoration of modern and contemporary works of art
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