Search results for " Circular"
showing 10 items of 253 documents
Magnetic Circular Dichroism in Two-Photon Photoemission
2009
We report the observation of magnetic circular dichroism (MCD) in two-photon photoemission (2PPE). The Heusler alloys Ni2MnGa and Co2FeSi were investigated by excitation with femtosecond laser light, showing MCD asymmetries of A=(3.5+/-0.5)x10;{-3} for Ni2MnGa and of A=(2.1+/-1.0)x10;{-3} for Co2FeSi, respectively. A theoretical explanation is provided based on local spin-density calculations for the magnetic dichroic response; the computed 2PPE MCD agrees well with the experiment. The observed 2PPE magnetic contrast represents an interesting alternative for future time-resolved photoemission studies on surface magnetism practicable in the laboratory.
Unconventional dihydrogen-bond interaction induced cyanide-bridged chiral nano-sized magnetic molecular wheel: synthesis, crystal structure and syste…
2019
A pair of cyanide-bridged 4d–3d heterobimetallic chiral macrocyclic enantiomeric magnetic complexes have been successfully assembled from the trans-dicyanoruthenium(III) building block [PPh4][Ru(Salen)(CN)2] (Salen = N,N-ethylenebis(salicylideneaminato)dianion) and [Mn((S,S/R,R)-Salcy)(H2O)2]ClO4 (Salcy = N,N′-(1,2-cyclohexanediylethylene)bis(salicylideneiminato)dianion) with the great help of the dihydrogen bond (DHB) interaction and characterized by elemental analysis, IR spectroscopy, circular dichroism (CD) and magnetic circular dichroism (MCD) spectroscopy. Single X-ray diffraction reveals that complex 1, {[Ru(Salen)(CN)2][R,R-Mn(Salcy)]}6·PPh3·6CH3CN·6CH3OH·12H2O, is a neutral dodecan…
Separation, isolation and stereochemical assignment of imazalil enantiomers and their quantitation in an in vitro toxicity test
2016
A simple method for the separation of the enantiomers of the fungicide imazalil was developed. Racemic imazalil was separated into its enantiomers with an enantiomeric purity of 99% using HPLC-UV with an enantioselective column (permethylated cyclodextrin) operated in reversed phase mode (water with 0.2% trimethylamine and 0.08% acetic acid and methanol). The absolute configuration of the separated enantiomers was assigned and unequivocally confirmed by optical rotation as well as by vibrational circular dichroism (VCD) and electronic circular dichroism (ECD) combined with ab-initio calculations. The same enantioselective column was also used to develop an HPLC-MS/MS method for the quantifi…
Investigations of Chl a aggregates cross-linked by dioxane in 3-methylpentane
1997
In this work, dioxane-bound aggregates of chlorophyll a are prepared in 3-methylpentane. The properties of the aggregates are studied by using steady-state and time-resolved spectroscopies. The Q -region absorption spectrum of the y chlorophyll a-dioxane aggregate shows four clearly resolvable narrow bands with comparable intensities. The band maxima are located at 683, 689, 698 and 702 nm. The emission spectrum consists of two emission bands centred at 699 and 702 nm suggesting the presence of two types of aggregates. High degree of fluorescence polarization is detected yielding the angles between the absorption transition moments with respect to the 702 nm emission transition moment. The …
Forever Young: Structural Stability of Telomeric Guanine Quadruplexes in the Presence of Oxidative DNA Lesions**
2021
International audience; Human telomeric DNA, in G-quadruplex (G4) conformation, is characterized by a remarkable structural stability that confers it the capacity to resist to oxidative stress producing one or even clustered 8-oxoguanine (8oxoG) lesions. We present a combined experimental/computational investigation, by using circular dichroism in aqueous solutions, cellular immunofluorescence assays and molecular dynamics simulations, that identifies the crucial role of the stability of G4s to oxidative lesions, related also to their biological role as inhibitors of telomerase, an enzyme overexpressed in most cancers associated to oxidative stress.
Grounds and Challenges for Implementing a Circular Economy in the European Road transport Sector
2017
Environmental challenges, especially in the form of resource depletion, pollution and greenhouse gas emission, are very important challenges for the socio-economic development. For this reason, the concept of a circular economy has been developed and is being implemented in different areas. In 2015, the European Union adopted the Circular Economy Package consisting of an “EU Action Plan for the Circular Economy”, presenting a set of actions aimed at achieving objectives of the circular economy in Europe. The goal of the paper is to describe and discuss key challenges facing implementation of the concept of the circular economy in the European road transport sector. First, the concept of a c…
STATE OF PRACTICE IN THE C&DW SECTOR WHILE PURSUING CIRCULAR ECONOMY: THE ITALIAN RECYCLED MATERIALS MARKET IN ROAD ENGINEERING
2022
Construction and demolition waste (C&DW) is mainly produced during the construction, demolition, or renovation activities of engineering structures and it accounts for a remarkable amount of the total C&DW generated, as it is estimated to be around 30%. This proportion differs across countries belonging to different types of economies and tends to be greater in countries with developing economies reaching 74% of total annual production. There is a plethora of applications that C&DW can be used for under a circular economic model and in this research study a focus is being given in the utilization of C&DW within the pavement engineering sector, and more specifically, in the u…
Understanding the current state of practice in the construction and demolition waste sector through the lenses of circular economy: The Italian recyc…
Construction and demolition waste (CeDw) is mainly produced during the construction, demolition, or renovation activities of civil engineering structures and it accounts for a remarkable amount of the total C&Dw generated, as it is estimated to be around 30%. This proportion differs between countries belonging to different types of economies and tends to be greater in countries with developing economies reaching 74% of total annual production. There is a plethora of applications that C&Dw can be used for under a circular economic model and in this research a focus is being given in the exploitation of C&Dw within the pavement engineering sector, and more specifically, in the uti…
The Sustainability of Reclaimed Asphalt as a Resource for Road Pavement Management through a Circular Economic Model
2019
The transition of the road engineering industry to a circular way of doing business requires more efficient and sustainable resources, energy, and waste management. The rates in which reclaimed asphalt is being recycled or reused in the asphalt mixture production process constitutes a crucial parameter in this transition. This paper aims at establishing a further step towards the combined circularity and sustainability of asphalt pavements, by introducing a framework for quantifying their Material Circularity Index. The framework is based on the methodology proposed by the Ellen MacArthur Foundation and accordingly tailored for the context of asphalt pavements. This study, thus, attempts to…
Comparing the Material Circularity Index of the Italian and Spanish motorways: A case study over the Mediterranean basin
2022
Closely following the attempt of the pavement engineering industry to comply with the principles of Circular Economy (CE) while simultaneously promoting its principles, it can be detected that a significant effort is being made towards the minimization of the energy and raw materials usually utilized. In this regard, Reclaimed Asphalt (RA) is a product that exhibits a tremendous exploitation potential. Knowing that by definition CE is restorative [1], regenerative, and aims to keep products, components, and materials at their highest utility and value at all times [2], i.e. it supports the “re-circulation” of materials and energy within the same or alternative product systems and thus the e…