Zirconium and titanium complexes supported by tridentate LX2 ligands having two phenolates linked to furan, thiophene, and pyridine donors: precatalysts for propylene polymerization and oligomerization

Zirconium and titanium complexes with tridentate bis(phenolate)-donor (donor = pyridine, furan and thiophene) ligands have been prepared and investigated for applications in propylene polymerization. The ligand framework has two X-type phenolates connected to the flat heterocyclic L-type donor at the 2,6- or 2.5- positions via direct ring-ring (sp^2-sp^2)linkages. The zirconium and titanium dibenzyl complexes have been prepared by treatment of the neutral bis(phenol)-donor ligands with M(CH_2Ph)_4 (M = Ti, Zr) with loss of 2 equiv of toluene. Titanium complexes with bis(phenolate)pyridine and -furan ligands and zirconium complexes with bis(phenolate)pyridine and -thiophene ligands have been characterized by single-crystal X-ray diffraction. The solid-state structures of the bis(benzyl)titanium complexes are roughly C_2 symmetric, while the zirconium derivatives display C_s and C^1 symmetry. The bis(phenolate)pyridine titanium complexes are structurally affected by the size of the substituents substituents (CMe_3 or CEt_3) ortho to the oxygens, the larger group leading to a larger C_2 distortion. Both titanium and zirconium dibenzyl complexes were found to be catalyst precursors for the polymerization of propylene upon activation with methylaluminoxane (MAO). The activities observed for the zirconium complexes are particularly notable, exceeding 10^6 g polypropylene/mol Zr center dot h in some cases. The bis(phenolate)pyridine titanium analogues are about 10^3 times less active, but generate polymers of higher molecular weight. When activated with MAO, the titanium bis(phenolate)furan and bis(phenolate)thiophene systems were found to promote propylene oligomerization

THE VERNACULAR HERITAGE OF GJIROKASTRA (ALBANIA): ANALYSIS OF URBAN AND CONSTRUCTIVE FEATURES, THREATS AND CONSERVATION STRATEGIES

Abstract. The old town of Gjirokastra (Albania), was included in the World Heritage List in 2005 thanks to the valuable presence of several remarkable examples of Ottoman-styled houses and in the integrity of the vernacular urban landscape. The urban structure is strongly influenced by the orography of the Drino valley and its slopes where the city was founded. Stone is the building material that characterizes the paving of the streets, the walls of the buildings and the roof coverings. The wood, mostly local, was used to build the frame structure of the upper floors and the roofs, in order to provide large windows and bright interior spaces. In December 2018, as part of the activities of the 3D Past project, founded by Eu Creative Europe Programme, Italian and Albanian students took part in a workshop in Gjirokastra. Such an initiative was designed to understand the tangible and intangible components of the vernacular heritage of Gjrokastra. In a multidisciplinary approach, students, professors, researchers and local experts analysed the morphological features of the historic center, the public spaces, and the traditional building systems. Traditional instruments such as the direct survey, the on-site observation and the interviews were adopted in combination with more innovative tools such as the laser scanner and the photogrammetry. This contribution not only illustrates the results of a multi-scale analysis, but it also highlights the transformations and threats that endanger the transmission of the unique characteristics of the city to the future generations. Moreover, it deals with the conservation strategies currently in use and some possible future measures that can contribute to the sustainable safeguard and development of the site

Characterisation of a single photon counting pixel system for imaging of low-contrast objects

In the framework of the Medipix collaboration the PCC, a single photon counting pixel chip, has been developed with the aim of improving the contrast resolution in medical imaging applications. The PCC consists of a matrix of 64x64 square pixels with 170 mm side length, each pixel comprising a 15 bit counter and a pulse height discriminator. The chip has been bump bonded to equally segmented 200 mm thick SI-LEC GaAs detectors showing a very high absorption energy for X-rays used in diagnostics. An absolute calibration of the system with a radioactive source and a synchrotron beam are described resulting in the value of the test input capacitance of ~24.7 fF. Using this value a full characterisation of the system from electrical measurements is presented. The entire system can reach a minimum threshold of ~2100 e- with ~250e- rms noise. One of the characteristics of the PCC is the possibility to adjust the thresholds of all pixels on a pixel-by-pixel basis with 3-bit precision. The threshold distribution after adjustment is ~120 e- rms. The spatial resolution of the system has been measured to be 3.61p/mm. A comparison of a tooth image taken with the PCC and with a screen-CDD system demonstrates its imaging capabilities

Are prices of new dwellings different? A spectral analysis of UK property vintages

The work makes two contributions to Hui’s (2011) dynamic house price classification. First, a house price ripple in cycles from Modern to Older dwellings is revealed and, second, as New housing is shown to have lower volatility than the other two. Using spectral analysis, it is argued that there is a 7½-year repeat buyer-second-hand cycle and a five year, first time buyer-New housing cycle, common to three house price vintages. These cycles reinforce each other every fifteen years, which corresponds with a Minsky super-cycle in housing finance. The equity of the owner-occupier is fortified by higher house prices whereas new builds extract embedded equity from the market. Government should support builders and facilitate access to market to first time buyers and through programmes like Help-to-Buy 1. However, to address the greater price instability that should follow, Government should impose a capital gains tax on the house seller

Hydrologic indicators of hot spots and hot moments of mercury methylation potential along river corridors

The authors acknowledge financial support from the National Science Foundation: EAR-1226741 (to M.B.S.) and EAR-1225630 (to J.D.B.), and from the REG Trust (to M.B.S.).The biogeochemical cycling of metals and other contaminants in river-floodplain corridors is controlled by microbial activity responding to dynamic redox conditions. Riverine flooding thus has the potential to affect speciation of redox-sensitive metals such as mercury (Hg). Therefore, inundation history over a period of decades potentially holds information on past production of bioavailable Hg. We investigate this within a Northern California river system with a legacy of landscape-scale 19th century hydraulic gold mining. We combine hydraulic modeling, Hg measurements in sediment and biota, and first-order calculations of mercury transformation to assess the potential role of river floodplains in producing monomethylmercury (MMHg), a neurotoxin which accumulates in local and migratory food webs. We identify frequently inundated floodplain areas, as well as floodplain areas inundated for long periods. We quantify the probability of MMHg production potential (MPP) associated with hydrology in each sector of the river system as a function of the spatial patterns of overbank inundation and drainage, which affect long-term redox history of contaminated sediments. Our findings identify river floodplains as periodic, temporary, yet potentially important, loci of biogeochemical transformation in which contaminants may undergo change during limited periods of the hydrologic record. We suggest that inundation is an important driver of MPP in river corridors and that the entire flow history must be analyzed retrospectively in terms of inundation magnitude and frequency in order to accurately assess biogeochemical risks, rather than merely highlighting the largest floods or low-flow periods. MMHg bioaccumulation within the aquatic food web in this system may pose a major risk to humans and waterfowl that eat migratory salmonids, which are being encouraged to come up these rivers to spawn. There is a long-term pattern of MPP under the current flow regime that is likely to be accentuated by increasingly common large floods with extended duration.PostprintPeer reviewe

Imaging spectroscopic performances for a Si based detection system

We present the imaging and spectroscopic capabilities of a system based on a single photon counting chip (PCC) bump-bonded on a Si pixel detector. The system measures the energy spectrum and the flux, produced by a standard mammographic tube. We have also made some images of low contrast details, achieving good results

THE EUROPEAN PROJECT "VERSUS+ / HERITAGE FOR PEOPLE". OBJECTIVES AND METHODOLOGY

Abstract. The project "VerSus+ / Heritage for PEOPLE", founded by the European Commission as part of the Creative Europe Culture Programme (Ref. 607593-CREA-1-2019-1-ES-CULT-COOP1) during the period 2019–2023, focuses on the transmission of knowledge to all branches of society and the general public. Its aim is to raise awareness on what constitutes the basis for the conservation of the tangible and intangible heritage as well as for a more sustainable contemporary architecture. This in-depth transmission of the lessons from vernacular heritage to future society is to be carried out in specific defined contexts, such as islands and archipelagos (geographically limited territories that are accessible to collaborators and administrative, technical and social agents), where vernacular heritage is under pressure, subjected to the transformations of contemporary life, particularly mass tourism. These pilot experiences should serve as a real testing ground for the implementation of actions for social participation, dissemination, education, communication, and promotion in different contexts and through different media. This project aims to reach out to society in order to showcase the sustainable qualities of the examples identified, through the establishment of an operative approach that can be adjusted to different contexts. The experiences on each island are expected to have repercussions throughout the region and, in turn, throughout the country in question, improving the perspectives and opportunities starting from best practices, and promoting the development of local skills. In addition, promotion and support from partners and associate partners will allow these experiences to be applied in other similar European and international contexts

Effective artifact removal in resting state fMRI data improves detection of DMN functional connectivity alteration in Alzheimer's disease

Artifact removal from resting state fMRI data is an essential step for a better identification of the resting state networks and the evaluation of their functional connectivity (FC), especially in pathological conditions. There is growing interest in the development of cleaning procedures, especially those not requiring external recordings (data-driven), which are able to remove multiple sources of artifacts. It is important that only inter-subject variability due to the artifacts is removed, preserving the between-subject variability of interest\u2014crucial in clinical applications using clinical scanners to discriminate different pathologies and monitor their staging. In Alzheimer's disease (AD) patients, decreased FC is usually observed in the posterior cingulate cortex within the default mode network (DMN), and this is becoming a possible biomarker for AD. The aim of this study was to compare four different data-driven cleaning procedures (regression of motion parameters; regression of motion parameters, mean white matter and cerebrospinal fluid signal; FMRIB's ICA-based Xnoiseifier\u2014FIX\u2014cleanup with soft and aggressive options) on data acquired at 1.5 T. The approaches were compared using data from 20 elderly healthy subjects and 21 AD patients in a mild stage, in terms of their impact on within-group consistency in FC and ability to detect the typical FC alteration of the DMN in AD patients. Despite an increased within-group consistency across subjects after applying any of the cleaning approaches, only after cleaning with FIX the expected DMN FC alteration in AD was detectable. Our study validates the efficacy of artifact removal even in a relatively small clinical population, and supports the importance of cleaning fMRI data for sensitive detection of FC alterations in a clinical environment