Development of radical processes triggered by the photochemical activity of transient organic intermediates

La química desenvolupada durant la meva tesi doctoral ha estat impulsada per la capacitat d'intermedis rics en electrons (anions fenolat i enamines quirals), generats transitòriament a partir de precursors fotoquímicament inactius (fenols i aldèhids), per arribar directament a un estat electrònicament excitat després de l'absorció de llum i, posteriorment, promovent la formació d'espècies radicalàries reactives a partir dels iodurs d'alquil adequats. En les transformacions estudiades, la formació dels radicals és a través de l'escissió reductora de l'enllaç carboni-iode del precursor de iodur d'alquil mitjançant mecanismes de transferència d'un sol electró (SET). Inicialment, he desenvolupat un nou enfocament per a la perfluoroalquilació fotoquímica directa de fenols substituïts. L'ús de llum visible simple, sense la necessitat de cap fotocatalitzador o iniciador de radicals, pot promoure la perfluoroalquilació o trifluorometilació aromàtica de fenols a temperatura ambient. En un segon projecte, he desenvolupat una nova metodologia per a la metilació o bencilació en α d'aldèhids mitjançant la fotoorganocatálisi. En aquest cas, la reacció es produeix en absència de catalitzadors fotoredox externs, i els compostos desitjats s'obtenen amb bons rendiments aïllats i elevada enantioselectivitat.La química desarrollada durante mi tesis doctoral ha sido impulsada por la capacidad de intermedios ricos en electrones (aniones fenolato y enaminas quirales), generados transitoriamente a partir de precursores fotoquímicamente inactivos (fenoles y aldehídos), para alcanzar directamente un estado electrónicamente excitado tras la absorción de luz y, posteriormente, promover la formación de especies radicalarias reactivas a partir de los yoduros de alquilo adecuados. En las transformaciones estudiadas, la formación de los radicales es a través de la escisión reductora del enlace carbono-yodo del precursor de yoduro de alquilo mediante mecanismos de transferencia de un solo electrón (SET). Inicialmente, he desarrollado un nuevo enfoque para la perfluoroalquilación fotoquímica directa de fenoles sustituidos. El uso de luz visible simple, sin necesidad de ningún fotocatalizador o iniciador de radicales, puede promover la perfluoroalquilación o trifluorometilación aromática de fenoles a temperatura ambiente. En un segundo proyecto, he desarrollado una nueva metodología para la metilación o bencilación en α de aldehídos mediante fotoorganocatálisis. En este caso, la reacción se produce en ausencia de catalizadores fotoredox externos, y los compuestos deseados se obtienen con buenos rendimientos aislados y elevada enantioselectividad.The chemistry developed during my doctoral thesis was driven by the ability of electron rich intermediates (phenolate anions and chiral enamines), transiently generated from photochemically inactive precursors (phenols and aldehydes), to directly reach an electronically excited state upon light absorption and subsequently promoting the formation of reactive radical species from suitable alkyl iodides. In the studied transformations, the radicals are formed through the reductive cleavage of the carbon-iodine bond within the alkyl iodide precursor via single-electron transfer (SET) mechanisms. Initially, I developed a new approach for the photochemical direct perfluoroalkylation of substituted phenols. The use of simple visible light, without the need of any photocatalyst or radical initiator, can promote an aromatic perfluoroalkylation or trifluoromethylation of phenols at ambient temperature. In a second project, I developed a new methodology for the enantioselective formal α-methylation and α-benzylation of aldehydes by means of photo-organocatalysis. The reaction occurs in the absence of external photoredox catalysts, and the desired compounds were obtained in good isolated yields with high enantioselectivity

Green Approach for Joint Management of Geo-Distributed Data Centers and Interconnection Networks

Every time an Internet user downloads a video, shares a picture, or sends an email, his/her device addresses a data center and often several of them. These complex systems feed the web and all Internet applications with their computing power and information storage, but they are very energy hungry. The energy consumed by Information and Communication Technology (ICT) infrastructures is currently more than 4\% of the worldwide consumption and it is expected to double in the next few years. Data centers and communication networks are responsible for a large portion of the ICT energy consumption and this has stimulated in the last years a research effort to reduce or mitigate their environmental impact. Most of the approaches proposed tackle the problem by separately optimizing the power consumption of the servers in data centers and of the network. However, the Cloud computing infrastructure of most providers, which includes traditional telcos that are extending their offer, is rapidly evolving toward geographically distributed data centers strongly integrated with the network interconnecting them. Distributed data centers do not only bring services closer to users with better quality, but also provide opportunities to improve energy efficiency exploiting the variation of prices in different time zones, the locally generated green energy, and the storage systems that are becoming popular in energy networks. In this paper, we propose an energy aware joint management framework for geo-distributed data centers and their interconnection network. The model is based on virtual machine migration and formulated using mixed integer linear programming. It can be solved using state-of-the art solvers such as CPLEX in reasonable time. The proposed approach covers various aspects of Cloud computing systems. Alongside, it jointly manages the use of green and brown energies using energy storage technologies. The obtained results show that significant energy cost savings can be achieved compared to a baseline strategy, in which data centers do not collaborate to reduce energy and do not use the power coming from renewable resources

Use of Carbon Nitrides as Photoactive Supports in Single‐Atom Heterogeneous Catalysis for Synthetic Purposes

In recent years, the field of dual photocatalysis has become an increasingly popular tool for the functionalization of organic substrates under mild operative conditions. Single-atom heterogeneous catalysts (SACs), where the metal atoms are stabilized by means of properly structured photoactive supports, are currently one of the frontiers of this research field. To this end, Carbon Nitrides (CNs) have emerged as ideal two-dimensional semiconducting supports, capable of stabilizing single metal sites (for instance: nickel, iron, among other) through nitrogen-rich structures. This Concept highlights the recent advances in the synthesis of carbon nitride-based SACs and their applications in light-driven dual-catalytic processes, also providing forward-looking opportunities within this research area

Morphology and Light‐Dependent Spatial Distribution of Spin Defects in Carbon Nitride

Carbon nitride (CN) is a heterogeneous photocatalyst that combines good structural properties and a broad scope. The photocatalytic efficiency of CN is associated with the presence of defective and radical species. An accurate description of defective states—both at a local and extended level—is key to develop a thorough mechanistic understanding of the photophysics of CN. In turn, this will maximise the generation and usage of photogenerated charge carriers and minimise wasteful charge recombination. Here the influence of morphology and light-excitation on the number and chemical nature of radical defects is assessed. By exploiting the magnetic dipole-dipole coupling, the spatial distribution of native radicals in CN is derived with high precision. From the analysis an average distance in the range 1.99–2.34 nm is determined, which corresponds to pairs of radicals located approximately four tri-s-triazine units apart

The Nickel Age in Synthetic Dual Photocatalysis: A Bright Trip Toward Materials Science

Recently, the field of dual photocatalysis has grown rapidly, to become one of the most powerful tools for the functionalization of organic molecules under mild conditions. In particular, the merging of Earth-abundant nickel-based catalytic systems with visible-light-activated photoredox catalysts has allowed the development of a number of unique green synthetic approaches. This goes in the direction of ensuring an effective and sustainable chemical production, while safeguarding human health and environment. Importantly, this relatively new branch of catalysis has inspired an interdisciplinary stream of research that spans from inorganic and organic chemistry to materials science, thus establishing itself as one dominant trend in modern organic synthesis. This Review aims at illustrating the milestones on the timeline evolution of the photocatalytic systems used, with a critical analysis toward novel applications based on the use of photoactive two-dimensional carbon-based nanostructures. Lastly, forward-looking opportunities within this intriguing research field are discussed

Differentiated karst spring behavior under changing hydrological conditions in the Cansiglio-Cavallo area (italian Alps)

Veneto, Friuli-Venezia Giulia, karst aquifer, water budget

Differentiated spring behavior under changing hydrological conditions in an alpine karst aquifer

Limestone massifs with a high density of dolines form important karst aquifers in most of the Alps, often with groundwater circulating through deep karst conduits and water coming out of closely spaced springs with flow rates of over some cubic meters per second. Although several hydrogeological studies and tracing experiments were carried out in many of these carbonate mountains in the past, the hydrogeology of most of these karst aquifers is still poorly known. Geological, hydrodynamic and hydrochemical investigations have been carried out in one of the most representative of these areas (Cansiglio-Monte Cavallo, NE Italy) since spring 2015, in order to enhance the knowledge on this important type of aquifer system. Additionally, a cave-to-spring multitracer test was carried out in late spring 2016 by using three different fluorescent tracers. This hydrogeological study allowed: 1) gathering new detailed information on the geological and tectonic structure of such alpine karst plateau; 2) defining discharge rates of the three main springs (Gorgazzo, Santissima, and Molinetto) by constructing rating curves; 3) understanding the discharging behavior of the system with respect to different recharge conditions; 4) better defining the recharge areas of the three springs. The three nearby springs (the spring front stretches over 5 km), that drain the investigated karst aquifer system, show different behaviors with respect to changing discharge conditions, demonstrating this aquifer to be divided in partially independent drainage systems under low-flow conditions, when their chemistry is clearly differentiated. Under high-flow conditions, waters discharging at all springs show more similar geochemical characteristics. The combination of geochemistry, hydrodynamic monitoring and dye tracing tests has shown that the three springs have different recharge areas. The study points out that even closely spaced karst springs, that apparently drain the same karst mountain, can have different behaviors, and thus distinctive reactions toward polluting events, a characteristic to be taken into account for their management

In vitro effects of tea tree oil (Melaleuca alternifolia essential oil) and its principal component terpinen-4-ol on swine spermatozoa

The growing interest towards essential oils stems from their biological capabilities that include antibacterial and antioxidant effects. Such properties may be extremely useful in the reproductive field; nonetheless essential oils show toxic effects that can lead to cell disruption. The present study aimed to evaluate and compare the effects of tea tree oil (TTO) and its principal component terpinen-4-ol (TER) on the morpho-functional parameters of swine spermatozoa. Experimental samples were prepared by suspending 15 7 10 7 spermatozoa in 5 mL of medium with different concentrations of the above-mentioned compounds: from 0.2 to 2 mg/mL at an interval of 0.2 for TTO, while TER concentrations were adjusted according to its presence in TTO (41.5%). After 3 h incubation at 16 \u25e6 C, samples were analyzed for pH, viability, acrosome status, and objective motility. The results highlighted a concentration-dependent effect of TTO with total motility as the most sensitive parameter. TER was better tolerated, and the most sensitive parameters were related to membrane integrity, suggesting a different pattern of interaction. The study confirms the importance of evaluating the effects of natural compounds on spermatozoa before exploiting their beneficial effects. Spermatozoa seem to be good candidates for preliminary toxicological screenings in the light of their peculiar properties

Non-invAsive VentIlation for early General wArd respiraTory failurE (NAVIGATE):A multicenter randomized controlled study. Protocol and statistical analysis plan

Few randomized trials have evaluated the use of non-invasive ventilation (NIV) for early acute respiratory failure (ARF) in non-intensive care unit (ICU) wards. The aim of this study is to test the hypothesis that early NIV for mild-moderate ARF in non-ICU wards can prevent development of severe ARF

Use of hydroxychloroquine in hospitalised COVID-19 patients is associated with reduced mortality: Findings from the observational multicentre Italian CORIST study

Background: Hydroxychloroquine (HCQ) was proposed as potential treatment for COVID-19. Objective: We set-up a multicenter Italian collaboration to investigate the relationship between HCQ therapy and COVID-19 in-hospital mortality. Methods: In a retrospective observational study, 3,451 unselected patients hospitalized in 33 clinical centers in Italy, from February 19, 2020 to May 23, 2020, with laboratory-confirmed SARS-CoV-2 infection, were analyzed. The primary end-point in a time-to event analysis was in-hospital death, comparing patients who received HCQ with patients who did not. We used multivariable Cox proportional-hazards regression models with inverse probability for treatment weighting by propensity scores, with the addition of subgroup analyses. Results: Out of 3,451 COVID-19 patients, 76.3% received HCQ. Death rates (per 1,000 person-days) for patients receiving or not HCQ were 8.9 and 15.7, respectively. After adjustment for propensity scores, we found 30% lower risk of death in patients receiving HCQ (HR=0.70; 95%CI: 0.59 to 0.84; E-value=1.67). Secondary analyses yielded similar results. The inverse association of HCQ with inpatient mortality was particularly evident in patients having elevated C-reactive protein at entry. Conclusions: HCQ use was associated with a 30% lower risk of death in COVID-19 hospitalized patients. Within the limits of an observational study and awaiting results from randomized controlled trials, these data do not discourage the use of HCQ in inpatients with COVID-19