281 research outputs found

    Lanthanide-Based Metal–Organic Frameworks with Single-Molecule Magnet Properties

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    Lanthanide metal-organic frameworks (Ln-MOFs) showing single-molecule magnet (SMM) properties are an ever-growing family of materials where the magnetic properties can be tuned by various interrelated parameters, such as the coordinated solvent, temperature, organic linkers, lanthanide ions and their coordination environment. An overview of the general synthetic methodologies to access MOFs/Ln-MOFs and the peculiarities and parameters to control and/or fine-tune their SMM behavior is herein presented. Additionally, diverse challenging strategies for inducing SMM/SIM behavior in an Ln-MOF are discussed, involving redox activity and chirality. Furthermore, intriguing physical phenomena such as the CISS effect and CPL are also highlighted

    MULTIDISCIPLINARY INVESTIGATION ON EARLY-MID HOLOCENE WILD CEREALS FOUND AT TAKARKORI (CENTRAL SAHARA)

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    Plant macroremains from rock shelters of central Sahara give information about the environmental conditions during the Holocene, and the adaptive strategies of human groups living in the area. Takarkori was excavated by the Italian-Libyan Archaeological Mission in the Acacus and Messak (directed by S. di Lernia, Sapienza University of Rome) and its chronology ranges from ca. 10,200 to ca. 4,600 cal yr BP (Cremaschi et al. 2014)

    Recent Advances on Anilato-Based Molecular Materials with Magnetic and/or Conducting Properties

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    The aim of the present work is to highlight the unique role of anilato-ligands, derivatives of the 2,5-dioxy-1,4-benzoquinone framework containing various substituents at the 3 and 6 positions (X = H, Cl, Br, I, CN, etc.), in engineering a great variety of new materials showing peculiar magnetic and/or conducting properties. Homoleptic anilato-based molecular building blocks and related materials will be discussed. Selected examples of such materials, spanning from graphene-related layered magnetic materials to intercalated supramolecular arrays, ferromagnetic 3D monometallic lanthanoid assemblies, multifunctional materials with coexistence of magnetic/conducting properties and/or chirality and multifunctional metal-organic frameworks (MOFs) will be discussed herein. The influence of (i) the electronic nature of the X substituents and (ii) intermolecular interactions i.e., H-Bonding, Halogen-Bonding, π-π stacking and dipolar interactions, on the physical properties of the resulting material will be also highlighted. A combined structural/physical properties analysis will be reported to provide an effective tool for designing novel anilate-based supramolecular architectures showing improved and/or novel physical properties. The role of the molecular approach in this context is pointed out as well, since it enables the chemical design of the molecular building blocks being suitable for self-assembly to form supramolecular structures with the desired interactions and physical propertie

    Multidisciplinary analysis of Early \u2013 Mid Holocene wild cereal remains from central Sahara (SW Libya).

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    .Pollen and plant macroremains from rock shelters of central Sahara give information about environmental conditions during the Holocene, and adaptive strategies of human groups living in the area. Wild cereals were long-time exploited and are prevalent among plants selected and transported to these sites. Spikelets and grains of Panicoideae are the most abundant plant remains found at Takarkori, a rock shelter in the Tadrart Acacus Mts. (SW Libya). They have been studied by means of morphological and molecular (ancient DNA) analyses. The excavation by the Italian-Libyan Archaeological Mission in the Acacus and Messak (Sapienza University of Rome and Libyan Department of Archaeology) exposed a surface of 140 m2. The deposit includes stone structures, fireplaces, plant accumulations and a burial area. The site (dated 10,200-4,600 cal yr BP) was occupied throughout Early and Middle Holocene, a pivotal period for human development as include the transition from hunter-gatherer subsistence to food production. Peculiarity of the sequences is the surprising preservation of organic matter. Systematic morphobiometrical analysis was carried out on 1,450 spikelets of Panicum, Echinochloa and Sorghum selected on the basis of their different cultural contexts. The records showed uniform size in each genus. aDNA was extracted testing different protocols and then was studied by the DNA barcoding technique using four chloroplast markers. Bioinformatic analysis of the results allowed to inspect the phylogenetic relationships between the archaeobotanical records and the modern species of African wild cereals

    Multidisciplinary analysis of wild cereals from the Holocene archaeological site of Takarkori (central Sahara)

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    Pollen and plant macroremains from central Sahara archaeological sites give information about the environmental conditions during the Holocene and the adaptive strategies of human groups living in the area . Wild cereals have been exploited for long time and are the prevalent taxa among those selected and transported to shelters and caves. The extraordinary state of preservation of the organic materials found at Takarkori allowed the morphological and molecular analyses of seeds/fruits belonging to the Poaceae family

    Wild cereals from Holocene central Sahara archaeological sites: aDNA and archaeobotany from the Takarkori rockshelter

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    Both pollen and macroremains recovered from archaeological sites point to a long-time exploitation of wild cereals and to the prevalence of these plants among those selected and transported to shelters and caves of central Sahara (southwestern Libya)(1). Spikelets, florets and grains of Panicoideae (Brachiaria, Cenchrus, Echinochloa, Panicum, Setaria, Urochloa, Sorghum) are the most abundant plant remains in these sites. The archaeological excavation of the Takarkori rockshelter by the Italian-Libyan Archaeological Mission in the Acacus and Messak (Central Sahara), Sapienza University of Rome (directed by S. di Lernia), exposed a surface of c. 120 m2 in extent. The 1.6 m thick deposit includes stone structures, fireplaces, plant accumulations, dung layers and a burial area. Layers were deposited during hunter-gatherer and later pastoralist occupational phases. Chronology ranged from c. 9000 to 4200 BP, and was based on stratigraphy, radiocarbon dates, and archaeological materials (2). Systematic morphological analysis was carried out on 200 spikelets/florets selected as representative of different chronological contexts. The records of Panicum, Echinochloa and Sorghum showed homogeneous typology and fairly uniform size in each genus. aDNA extraction confirming the morphological identifications of the three taxa was obtained by Olmi et al. (3). aDNA was successfully performed using several methods (4, 5) and then assayed using PCR with a primer set for the rbcL gene. New aDNA extraction was obtained from Panicum spikelets and the analysis of matK, trnH-psbA and trnL barcode regions may help to identify the records at species level

    chameleon behaviour of iodine in recovering noble metals from weee towards sustainability and zero waste

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    The peculiar properties of iodine and safe lixiviants for sustainable and effective noble-metal recovery from shredded WEEE

    Designing Magnetic NanoMOFs for Biomedicine: Current Trends and Applications

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    Metal–organic frameworks (MOFs) have shown a great potential in biomedicine due to their promising applications in different fields, including drug delivery, thermometry, theranostics etc. In this context, the development of magnetic sub-micrometric or nanometric MOFs through miniaturization approaches of magnetic MOFs up to the nanoscale still represents a crucial step to fabricate biomedical probes, especially in the field of theranostic nanomedicine. Miniaturization processes have to be properly designed to tailor the size and shape of particles and to retain magnetic properties and high porosity in the same material, fundamental prerequisites to develop smart nanocarriers integrating simultaneously therapeutic and contrast agents for targeted chemotherapy or other specific clinical use. An overview of current trends on the design of magnetic nanoMOFs in the field of biomedicine, with particular emphasis on theranostics and bioimaging, is herein envisioned

    Population Saturation in Trivalent Erbium Sensitized by Organic Molecular Antennae

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    We investigate sensitization efficiency of near-infrared emission and population saturation of trivalent erbium in erbium quincilinolato complexes photoexcited into the absorption band of the organic sensitizer. At low excitation levels, we find high (similar to 80%) sensitization efficiencies. We observe excited state population saturation at inversion threshold under subnanosecond pumping at the level of one injected photoexcitation per complex

    The representativeness of Olea pollen from olive groves and the Late Holocene landscape reconstruction in central Mediterranean

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    Modern pollen spectra are an invaluable reference tool for paleoenvironmental and cultural landscape reconstructions, but the importance of knowing the pollen rain released from orchards remains underexplored. In particular, the role of cultivated trees is in past and current agrarian landscapes has not been fully investigated. Here, we present a pollen analysis of 70 surface soil samples taken from 12 olive groves in Basilicata and Tuscany, two regions of Italy that exemplify this cultivation in the Mediterranean basin. This study was carried out to assess the representativeness of Olea pollen in modern cultivations. Although many variables can influence the amount of pollen observed in soils, it was clear that most of the pollen was deposited below the trees in the olive groves. A rapid decline in the olive pollen percentages (c. 85% on average) was found when comparing samples taken from IN vs. OUT of each grove. The mean percentages of Olea pollen obtained from the archaeological sites close to the studied orchards suggest that olive groves were established far from the Roman farmhouses of Tuscany. Further south, in the core of the Mediterranean basin, the cultivation of Olea trees was likely situated approximately 500\u20131000 m from the rural sites in Basilicata, and dated from the Hellenistic to the Medieval period
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