2,446 research outputs found

    Two steps one pot process for the conversion of dimethylfuran to pyrrole compounds with almost null E factor

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    The replacement of the oil-based chemicals with those derived from biomasses is one of the most exciting challenges of the last decades. For example, 1,4-dicarbonyl compounds have a great importance in chemical synthesis, thanks to their high chemoselectivity and there is an increasing interest for preparing them from biomasses. In particular, 2,5-hexanedione could be synthesized starting from lignocellulosic sources, through the acid-ring opening reaction of 2,5-dimethylfuran as the bio-based feedstock.[1] The reaction of 2,5-hexanedione and a generic primary amine leads to pyrrole compounds. Many examples have been reported by some of the authors.[2] In this work a sustainable process for the preparation of pyrrole compounds starting from a bio-based reagent has been developed. The selected starting material was 2,5-dimethyl furan. In this work, the ring opening reaction of 2,5-dimethylfuran was optimized by tuning parameters such as the amount of water, type and amount of acid, time and temperature. 2,5-hexanedione was obtained with a high yield (95%) without the need of purification. Then, different primary amines, in particular biosourced, have been used to prepare a variety of pyrrole compounds, with high yield (at least 90%) and with high carbon efficiency, without producing waste. The pyrrole compounds have then been used for the functionalization of a nanosized graphite, promoting the exfoliation to few layers graphene

    Chemical functionalization of graphene surface as filler for rubber compounds

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    Over the last few years, the surface modification of fillers for high-level technological applications such as polymer composites for tyre industry, conductive inks and coatings has seen a considerable increase in interest since it can increase mechanical, electrical, and thermal properties of the final material. Nano-sized carbon allotropes such as graphene and carbon nanotubes are a suitable class of compounds for these purposes: high thermal and electrical conductivity along with considerable mechanical reinforcement are the main improvements that these fillers bring to the composite and their elevated surface area allows to reduce the filler volume ratio compared to more common alternatives. An efficient and reliable method to modify the surface of these nano-fillers is the so-called pyrrole methodology, a mild procedure that involves bio-sourced reagents to introduce functional groups on the graphitic planes and that has been recently employed in the fabrication of elastomeric composites with improved mechanical properties. In order to understand the mechanism beneath the interaction between the pyrrole and the substrate and thus the behavior of the functionalized filler, a more in-depth analysis is requested. A theoretical work based on molecular dynamics simulations and a DFT study were performed in order to investigate the interaction energy, the geometry of interaction and the mobility of N-substituted pyrrole molecules adsorbed on the graphene planes. This theoretical study at atomistic level can help design a new class of high-performance fillers by better understanding the interaction mechanism given the important role of supramolecular interactions

    Outcome Prognostication of Acute Brain Injury using the Neurological Pupil Index (ORANGE) study: protocol for a prospective, observational, multicentre, international cohort study.

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    The pupillary examination is an important part of the neurological assessment, especially in the setting of acutely brain-injured patients, and pupillary abnormalities are associated with poor outcomes. Currently, the pupillary examination is based on a visual, subjective and frequently inaccurate estimation. The use of automated infrared pupillometry to measure the pupillary light reflex can precisely quantify subtle changes in pupillary functions. The study aimed to evaluate the association between abnormal pupillary function, assessed by the Neurological Pupil Index (NPi), and long-term outcomes in patients with acute brain injury (ABI). The Outcome Prognostication of Acute Brain Injury using the Neurological Pupil Index study is a prospective, observational study including adult patients with ABI requiring admission at the intensive care unit. We aimed to recruit at least 420 patients including those suffering from traumatic brain injury or haemorrhagic strokes, over 12 months. The primary aim was to assess the relationship between NPi and 6-month mortality or poor neurological outcome, measured by the Extended Glasgow Outcome Score (GOS-E, poor outcome=GOS-E 1-4). Supervised and unsupervised methods and latent class mixed models will be used to identify patterns of NPi trajectories and Cox and logistic model to evaluate their association with outcome. The study has been approved by the institutional review board (Comitato Etico Brianza) on 16 July 2020. Approved protocol V.4.0 dated 10 March 2020. The results of this study will be published in peer-reviewed journals and presented at conferences. NCT04490005

    Use of proton pump inhibitors and risk of ischemic events in the general population

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    BACKGROUND AND AIMS: A potential increased risk of cardiovascular events has been suggested for proton pump inhibitors (PPIs), the most commonly prescribed drugs for the management of upper gastrointestinal disorders. We aimed to estimate the risk of hospitalization for cardio/cerebrovascular (CV) events in a cohort of incident PPI users. METHODS: A nested case-control study was carried out using regional healthcare utilization databases. For each case (hospitalization for non-haemorrhagic CV event), up-to-five controls randomly selected from the cohort were matched by gender, age at cohort entry, and index date. Exposure was estimated as recency of therapy (current, recent and past users) and number of days covered. Adjusted conditional logistic regression was used to estimate the association between exposure and outcome. RESULTS: Among new PPI users, we identified 17,832 cases and 89,160 controls (males 64.9%; mean age 58.9 years). Cases showed a significantly higher prevalence of use of drugs for diabetes, hypertension and hypercholesterolemia than controls. Risk of CV events was significantly higher for current (OR 1.61; 95%CI 1.55-1.68) and recent users (OR 1.15; 95%CI 1.06-1.26) compared to past users. Analogous results were found stratifying for cardiovascular (ORcurrent 1.71; 95%CI 1.63-1.81) and cerebrovascular events (ORcurrent 1.43; 95%CI 1.34-1.54). The increased risk was confirmed in subgroups by antithrombotic, statin use, or exposure duration. The same analysis for H2-antagonists use showed no significant results. CONCLUSIONS: In primary care setting, PPI use was independently associated with increased risk of first-time cardiovascular event, consistent with the evidence that PPIs adversely impact vascular function, underlying the need to promote appropriate prescribing of these drugs

    Teachers’ stress experiences during COVID-19-related emergency remote teaching: Results from an exploratory study

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    The study provides a portrait of teachers’ stress experience in the face of the needed introduction of information systems (IS) during COVID-19-related emergency remote teaching. Researchers contacted the headmasters at several Italian schools, who choose teacher’s representatives. The latters shared the online questionnaire among colleagues; the teachers voluntarily decided to participate. The cross-sectional study involved 237 Italian teachers (81.5% female; Mage = 50.20; SDage = 8.87). This survey wanted to detect information systems-related distress and eustress on the job, and technostress creators and inhibitors. Descriptive statistics, correlational analyses, and a multiple regression model using structural equation modeling were run. As according to the model, IS-related distress and eustress on the job were the dependent variables, technostress creators and inhibitors the independent ones, and respondents’ gender and age the control ones. Both technostress creators and inhibitors showed significant relationships with IS-related distress and eustress. Technostress creators showed a positive relationship with IS-related distress and a negative one with IS-related eustress; conversely, technostress inhibitors showed an opposite pattern of relationships. Only technostress creators significantly associate to both age and gender in the model, suggesting that older, female teachers tended to experience more technostress creators. Due to the increases in remote work, the awareness of IS-related stress experiences represents a key factor to evaluate work-related risks and prevent stress-related problems. The results from this study suggest that using technologies can represent both a threat to one’s well-being, highlighting the need to provide adequate trainings and support, but also a resource for personal enrichment

    Transition metal nanoparticles on pyrrole-decorated sp2 carbon allotropes for selective hydrogen isotopic exchange

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    Compared to homogeneous catalysts, heterogeneous systems possess more attractiveness in the chemical industry because of the easier separation from the reaction products, lower amount of wastes, larger recyclability and lower toxicity and corrosiveness. Preparation of supported metal nanoparticles often requires energy demanding techniques such as laser ablation, electrochemical reduction, and high temperature heat treatments. In this work we present a facile and sustainable method to functionalize multi-walled carbon nanotubes (MWCNTs) and exploit the novel surface reactivity to deposit Ruthenium nanoparticles. Serinol pyrrole (SP) was synthesized and, through a Domino reaction, grafted on carbon nanotubes’ surface. Mild reducing conditions were employed to decorate CNT-SP with Ruthenium nanoparticles. The latter adduct was characterized by means of X-ray diffraction and transmission electron microscopy. Ru/CNT-SP was then tested in the selective deuteration of quinoline. High selectivity and conversion, determined through H-NMR, were achieved compared to commercial Ru/C catalysts. The results obtained in this work led to the filing of two patent applications

    Transition metal nanoparticles on pyrrole-decorated sp2 carbon allotropes for selective hydrogen isotopic exchange

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    Compared to homogeneous catalysts, heterogeneous systems possess more attractiveness in the chemical industry because of the easier separation from the reaction products, lower amount of wastes, larger recyclability, and lower toxicity and corrosiveness. Objective of this research was to prepare more efficient and more selective heterogeneous catalysts, by anchoring transition metal cations and nanoparticles on nitrogen decorated sp2 carbon allotrope (CA), which were functionalized with pyrrole compounds. Triethylenetetramine pyrrole (TETAP) was selected as the pyrrole compound: it was synthesized and grafted onto multiwalled carbon nanotubes and high surface area graphite with efficient and viable methodology. The CA/TEPAP adduct was used as the support of transition metal nanoparticles. It is here reported the example of ruthenium supported catalyst, investigated by means of elemental and surface area analyses, X-ray diffraction, transmission electron microscopy. The catalyst was used for the Hydrogen Isotopic Exchange (HIE) of aromatic compounds of pharmaceutical interest. Outstanding selectivity was obtained
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