Ti and Zr amino-tris(phenolate) catalysts for the synthesis of cyclic carbonates from CO2 and epoxides

Herein, we report the application of four amino-tris(phenolate)-based metal complexes incorporating Ti(IV) or Zr(IV) centres (2a-3b) as homogeneous catalysts for the conversion of CO2 and epoxides into cyclic carbonates. The four complexes were synthesised, characterised and then evaluated in combination with tetrabutylammonium iodide, bromide or chloride as binary catalytic systems for the reaction of CO2 with 1,2-epoxyhexane as epoxide substrate at 12 bar CO2 pressure and 90 °C for 2 h. The catalytic systems comprising the two Ti(IV) complexes (2a and 2b) showed similar performance. One notable exception was the catalytic system consisting of titanium complex 2b, bearing an axial Cl-ligand, and tetrabutylammonium chloride, which displayed higher catalytic activity compared to other titanium-based systems. Even higher activity was achieved with Zr(IV) complex 3a, bearing an axial isopropoxide ligand, which reached turnover numbers (TONmetal) up to 1920 for the reaction of CO2 with 1,2-epoxyhexane at 12 bar CO2 pressure and 90 °C for 2 h. This performance is comparable with that of state-of-the-art catalysts for this reaction. The catalytic system consisting of complex 3a and tetrabutylammonium bromide was explored further by investigating its applicability with a broad substrate scope, achieving quantitative conversion of several epoxides with CO2 into cyclic carbonate products at 90 °C and 12 bar CO2 pressure for 18 h. The selectivity towards the cyclic carbonate products was ≥ 98% for all studied terminal epoxides and ≥ 80% for all examined cyclohexene-type epoxides

Electrically-Responsive Reversible Polyketone/MWCNT Network through Diels-Alder Chemistry

This study examines the preparation of electrically conductive polymer networks based on furan-functionalised polyketone (PK-Fu) doped with multi-walled carbon nanotubes (MWCNTs) and reversibly crosslinked with bis-maleimide (B-Ma) via Diels-Alder (DA) cycloaddition. Notably, the incorporation of 5 wt.% of MWCNTs results in an increased modulus of the material, and makes it thermally and electrically conductive. Analysis by X-ray photoelectron spectroscopy indicates that MWCNTs, due to their diene/dienophile character, covalently interact with the matrix via DA reaction, leading to effective interfacial adhesion between the components. Raman spectroscopy points to a more effective graphitic ordering of MWCNTs after reaction with PK-Fu and B-Ma. After crosslinking the obtained composite via the DA reaction, the softening point (tan(delta) in dynamic mechanical analysis measurements) increases up to 155 degrees C, as compared to the value of 130 degrees C for the PK-Fu crosslinked with B-Ma and that of 140 degrees C for the PK-Fu/B-Ma/MWCNT nanocomposite before resistive heating (responsible for crosslinking). After grinding the composite, compression moulding (150 degrees C/40 bar) activates the retro-DA process that disrupts the network, allowing it to be reshaped as a thermoplastic. A subsequent process of annealing via resistive heating demonstrates the possibility of reconnecting the decoupled DA linkages, thus providing the PK networks with the same thermal, mechanical, and electrical properties as the crosslinked pristine systems

Analisi ed interpretazione del dissesto statico di Palazzo Bourbon-Del Monte a Piancastagnaio

Il presente lavoro si colloca nell’ambito degli studi volti a fornire un’interpretazione dei dissesti che interessano gli edifici in muratura attraverso l’analisi di un caso di studio: il palazzo Bourbon- Del Monte, un palazzo nobiliare del XVII secolo sito nel comune di Piancastagnaio (SI). Scopo della presente memoria è valutare le cause che hanno prodotto il dissesto dell’edificio nella prospettiva di un futuro intervento di consolidamento strutturale e di restauro

CO2-fixation into cyclic and polymeric carbonates: Principles and applications

The reaction between carbon dioxide and epoxides is an attractive pathway for CO2-utilisation as it can lead to the formation of two different, yet valuable, products: cyclic and polymeric carbonates. In this review, the advancements made within this field are critically discussed with special attention to the potential of these two classes of compounds as green chemical products. First, an overview is provided of the various types of homogeneous and heterogeneous catalytic systems developed for achieving the reaction of carbon dioxide with epoxides with high activity and selectivity towards either the cyclic or the polymeric carbonate products. Then, the chemical and physical properties of the cyclic and polycarbonate products are discussed, focussing on the correlation between such properties and the potential applications of each class of compounds. Finally, the most relevant applications of these materials, both potential and industrially implemented, are critically reviewed covering the fields of polymer products, energy storage devices, and biomedical and pharmaceutical applications

Pattern of activation during delayed matching to sample task predicts functional outcome in people at ultra high risk for psychosis

Background Clinical outcomes in people identified as at ultra-high risk (UHR) for psychosis are remarkably heterogeneous, and are difficult to predict on the basis of the presenting clinical features. Individuals at UHR are at risk of poor functional outcome regardless of development of psychotic disorder. The aim of the present study was to assess whether there is a relationship between functional neuroimaging measures at presentation and functional outcome as measured by the GAF three years after scanning. Methods Functional magnetic resonance imaging (fMRI) data were collected during an object working memory task in 34 ultra-high risk (UHR) subjects and 20 healthy controls. On the basis of their GAF scores at follow up, the UHR participants were divided into subgroups with good and poor functional outcomes, respectively. Results At baseline, the UHR group differed from controls in showing altered frontal and cuneus/posterior cingulate activation. Significant group x task interactions were found in the left cuneus and posterior cingulate gyrus, reflecting differential responses to the task conditions. Within the UHR sample, the subgroup with a poor functional outcome exhibited altered activation in frontal, temporal and striatal regions, and reduced deactivation within default-mode network regions, relative to those with a good outcome. Within the whole UHR sample, in these regions the local task response was correlated with the GAF score at follow up. Conclusions The findings suggest a potential role of functional neuroimaging in the prediction of outcomes in people at high clinical risk of psychosis

Clinical and neuropsychological features of violence in schizophrenia: A prospective cohort study

The increased risk of violence in schizophrenia has been linked to several environmental, clinical and neuropsychological factors, including executive dysfunction. However, data about the nature of these effects are mixed and controversial. The main aim of this study was to investigate the relationship between clinical and neuropsychological factors with violence risk in patients with schizophrenia, taking into account current psychopathology and lifetime alcohol use. We compared a sample of patients living in Residential Facilities (RFs) with schizophrenia and a past history of interpersonal violence (vSZ, N=50) to patients with schizophrenia matched on age, gender and alcohol abuse/dependence but with no violence history (nvSZ, N=37). We then established the association between the clinical and neuropsychological factors that predicted violence over a 1year follow-up period. The results revealed that vSZ patients living in RFs were characterized by greater compulsory hospital admissions, higher anger and less negative symptoms as compared to nvSZ patients. vSZ patients performed better on executive and motor tasks than nvSZ; however, these differences appeared to be explained by the lower negative psychotic symptom in the vSZ group. Both groups were involved in episodes of violence during the follow-up period; among the two, the vSZ patients were more likely to be violent. Negative symptoms predicted less verbal aggression at 1year follow-up. Overall, these findings support a key role of negative rather than positive symptoms in driving violence risk among SZ patients living in RFs, in a manner that negative symptoms are linked to a lower risk of violence

Anti-depressive therapies after heart transplantation

OBJECTIVE: Despite an improved quality of life, about 33% of heart transplant recipients will develop depressive symptoms post-operatively. To date, no review has explored the efficacy and safety of pharmacologic or psychologic interventions in this patient group. METHODS: We conducted a comprehensive Medline, EmBase, Psycinfo search for studies of the treatment of depression in heart transplant recipients. RESULTS: We identified 34 studies of variable methodologic quality. Selective serotonin re-uptake inhibitors (SSRIs), particularly citalopram and new-generation anti-depressants (mirtazapine), seem to represent the best therapeutic choices for this population. Tricyclic anti-depressants (TCAs), and electroconvulsive therapy (ECT) should be reserved for severe depression unresponsive to other treatments, whereas monoamine oxidase inhibitors (MAOIs) should be avoided. St John's wort, an alternative herbal drug, has been associated with life-threatening immunosuppression. Psychologic therapy offers further advantages after heart transplantation. CONCLUSIONS: Further well-conducted, randomized, controlled trials are needed to clarify the efficacy and the safety of pharmacologic (SSRIs and atypical anti-depressants) and psychologic interventions in the management of depression after heart transplantation

Pickering Emulsions and Antibubbles Stabilized by PLA/PLGA Nanoparticles

Micrometer-sized double emulsions and antibubbles were produced and stabilized via the Pickering mechanism by colloidal interfacial layers of polymeric nanoparticles (NPs). Two types of nanoparticles, consisting either of polylactic acid (PLA) or polylactic-co-glycolic acid (PLGA), were synthesized by the antisolvent technique without requiring any surfactant. PLA nanoparticles were able to stabilize water-in-oil (W/O) emulsions only after tuning the hydrophobicity by means of a thermal treatment. A water-in-oil-in-water (W/O/W) emulsion was realized by emulsifying the previous W/O emulsion in a continuous water phase containing hydrophilic PLGA nanoparticles. Both inner and outer water phases contained a sugar capable of forming a glassy phase, while the oil was crystallizable upon freezing. Freeze drying the double emulsion allowed removing the oil and water and replacing them with air without losing the three-dimensional (3D) structure of the original emulsion owing to the sugar glassy phase. Reconstitution of the freeze-dried double emulsion in water yielded a dispersion of antibubbles, i.e., micrometric bubbles containing aqueous droplets, with the interfaces of the antibubbles being stabilized by a layer of adsorbed polymeric nanoparticles. Remarkably, it was possible to achieve controlled release of a flourescent probe (calcein) from the antibubbles through heating to 37 °C leading to bursting of the antibubbles