Porous metallosilicates for heterogeneous, liquid-phase catalysis: perspectives and pertaining challenges

Porous silicates containing dilute amounts of tri-, tetraand penta-valent metal sites, such as TS-1, Sn-β and Fe- ZSM-5, have recently emerged as state of the art catalysts for a variety of sustainable chemical transformations. In contrast with their aluminosilicate cousins, which are widely employed throughout the refinery industry for gas-phase catalytic transformations, such metallosilicates have exhibited unprecedented levels of performance for a variety of liquidphase catalytic processes, including the conversion of biomass to chemicals, and sustainable oxidation technologies with H2O2. However, despite their unique levels of performance for these new types of chemical transformations, increased utilization of these promising materials is complicated by several factors. For example, their utilization in a liquid, and often polar, medium hinders process intensification (scaleup,catalyst deactivation). Moreover, such materials do not generally exhibit the active-site homogeneity of conventional aluminosilicates, and they typically possess a wide variety of active-site ensembles, only some of which may be directly involved in the catalytic chemistry of interest. Consequently,mechanistic understanding of these catalysts remains relatively low, and competitive reactions are commonly observed. Accordingly, unified approaches towards developing more active, selective and stable porous metallosilicates have not yet been achieved. Drawing on some of the most recent literature in the field, the purpose of this mini review is both to highlight the breakthroughs made with regard to the use of porous metallosilicates as heterogeneous catalysts for liquidphase processing, and to highlight the pertaining challenges that we, and others, aim to overcome during the forthcoming years

Ruolo della radiomica nella stadiazione, stratificazione del rischio e predizione della prognosi del tumore del colon non metastatico

Il cancro del colon è uno dei tumori più comuni al mondo e il percorso decisionale terapeutico dipende dal sistema di stadiazione TNM e dalla presenza di fattori di rischio clinici. Tuttavia, nel caso di pazienti con malattia non metastatica, la valutazione di schemi di trattamento personalizzati rappresenta una sfida clinica. Negli ultimi anni, la radiomica si è affermata come nuovo strumento per superare i limiti dell'imaging convenzionale, passando da un’analisi soggettiva e qualitativa ad una oggettiva e quantitativa Nel nostro studio abbiamo indagato e dimostrato le buone capacità dell’analisi radiomica nel distinguere, dalle tc stadiative preoperatorie dei pazienti con neoplasia del colon in Stadio II, i tumori T3 dai T4; distinzione che risulta fondamentale nella stratificazione del rischio dei pazienti, per selezionare i gruppi a maggior rischio che possano beneficiare maggiormente di protocolli di terapia personalizzati. Abbiamo, dunque, sviluppato un modello radiomico per predire le caratteristiche di malattia ad alto rischio dei tumori del colon non metastatici. Tutti i pazienti sono stati trattati con resezione chirurgica e abbiamo utilizzato i dati clinicopatologici per dividere la popolazione di partenza in pazienti ad alto rischio e senza rischio in base alla presenza di almeno un fattore di rischio clinico (la stadiazione T4, LVI, PNI, tumor budding e metastasi linfonodali) [41, 42]. Abbiamo, quindi, confrontato le caratteristiche radiomiche stabili tra pazienti ad alto rischio e non, e le caratteristiche radiomiche significative sono state utilizzate per costruire un modello predittivo radiomico, validato mediante coorte esterna. Il modello ha ottenuto buone prestazioni nel predire la malattia ad alto rischio, evidenziando il ruolo promettente della radiomica nella stratificazione del rischio dei pazienti

Catalytic methodologies for C(sp3)-F bond formation with heterogeneous catalysts

Fluorinated compounds are extremely desirable in several fields of the chemical industry, such as pharmaceuticals, materials and agrochemicals. Consequently, the development of novel methods of fluorination represents a major challenge in contemporary chemistry. Although several breakthroughs have been achieved in this area in recent years, the development of an active, stable, reusable and truly heterogeneous catalyst, able to perform selective C(sp3)-F formation, has not yet been achieved. Accordingly, this thesis explores the applicability of heterogeneous catalysts, to perform novel and selective C(sp3)-F bond formations. Different strategies to achieve C(sp3)-F bond synthesis were explored, including: i) fluorination of preactivated substrates (e.g. carboxylic acids), and ii) direct C(sp3)-H fluorination. Firstly, the applicability of heterogeneous materials, such as AgxO/TiO2 and pure TiO2, were investigated for decarboxylative fluorination reactions (R-COOH → R-F), with (photofluorination) and without the employment of light sources. Following an investigation of the catalytic performances of AgxO/TiO2 and pure TiO2 for fluorination of pre-activated substrates, an alternative route, whereby the applicability of heterogeneous materials for direct C(sp3)-H fluorination, was explored. Although more elegant and desirable, direct C(sp3)-H fluorination represents an immense challenge, mainly due to the scarce substrate reactivity, which typically results in a requirement of harsher reaction conditions. Due to the challenges associated with activation of C(sp3)-H bonds, two different systems to achieve direct C(sp3)-H fluorination were investigated. Firstly, the viability of benzylic fluorinations was explored, as these substrates represent excellent model substrates with slightly activated C-H bonds. Secondly, substrates possessing less active C(sp3)-H bonds, such as cyclooctane, were investigated for direct alkane fluorination

Open versus laparoscopic splenectomy a meta-analysis of larger series

Background: Minimally invasive surgery for elective splenectomy has become a routine procedure in all laparoscopic centers. After first case series, many groups has published comparative studies between open and laparoscopic approach. For this purpose, a meta-analysis investigating comparative studies of open versus laparoscopic approach for splenectomy was performed.Methods: All kinds of manuscripts were reviewed, and we included the only studies with a laparoscopic group number >= 50 cases.Results: The literature search, performed until December 31, 2019, identified a total of 564 records. After full-text analysis, twelve studies were included in the meta-analysis. Operative time was higher for the laparoscopic group in all but one study. The length of stay, morbidity and mortality were less frequent in the laparoscopic group.Conclusions: The gain of shorter hospital-stay associated with the good outcomes suggests performing splenectomy by a laparoscopic procedure

Acceptorless alcohol dehydrogenation catalysed by Pd/C

Although the selective oxidation of alcohols to carbonyl compounds is a critical reaction, it is often plagued by several challenges related to sustainability. Here, the continuous, acceptorless dehydrogenation of alcohols to carbonyl compounds over heterogeneous catalysts was demonstrated, in the absence of oxidants, bases or acceptor molecules. In addition to improving selectivity and atom efficiency, the absence of an acceptor resulted in the co‐production of molecular H2, a clean energy source, and permitted dehydrogenation to proceed at >98 % selectivity at turnover frequency values amongst the highest in the literature. Moreover, excellent durability was observed during continuous operation over 48 h, reaching space‐time yields of 0.683 g(product) mL−1 h−1, better than the state of the art by over two orders of magnitude. Alongside these breakthroughs, the basic kinetic parameters of the reaction were also determined, allowing some of the elementary reaction steps to be identified

Developing a continuous process for isosorbide production from renewable sources

Increasing demand for isosorbide has led to the search for sustainable and efficient methods for its production from sorbitol, a biomass‐derived platform molecule. However, sorbitol dehydration to isosorbide is currently performed with mineral acids, resulting in safety and toxicity issues. Although some progress has been made towards replacement of liquid acids with heterogeneous catalysts, continuous systems with good stability, selectivity and productivity remain scarce. Herein, sorbitol dehydration to isosorbide is efficiently performed in a continuous, liquid‐phase plug flow reactor, utilising an acidic zeolite (H‐β (38)) as solid catalyst. H‐β (38) is shown to catalyse the reaction without loss of activity for 55 hours on stream, achieving an isosorbide productivity of 9670 gisosorbide/kgcatalyst. This value is 4 times greater than any other continuous process reported in literature to date, even though the reaction was terminated prior to any loss of activity being detected. Diagnostic kinetic studies reveal improved operational conditions, and characterisation of the post‐reaction catalyst is provided

Laparoscopic versus open rectal resection. a 1:2 propensity score-matched analysis of oncological adequateness, short- and long-term outcomes

Laparoscopic resections for rectal cancer are routinely performed in high-volume centres. Despite short-term advantages have been demonstrated, the oncological outcomes are still debated. The aim of this study was to compare the oncological adequateness of the surgical specimen and the long-term outcomes between open (ORR) and laparoscopic (LRR) rectal resections

Catalytic formation of C(sp3 )–F bonds via decarboxylative fluorination with mechanochemically-prepared Ag2O/TiO2 heterogeneous catalysts

Mechanochemically-prepared, Ag2O-containing solid materials, are shown to be efficient heterogeneous catalysts for the synthesis of C(sp3)-F bonds via decarboxylative fluorination. Five catalytic cycles without loss of intrinsic activity could be performed with the optimal catalyst, composed of 1 wt% Ag2O supported on TiO2 (P25), despite the challenging conditions. The catalyst is easily prepared from the corresponding oxides in 20 minutes by simple mechanical mixing methods. In addition to ease of separation and re-use, the turnover numbers obtained over the solid catalyst are over one order of magnitude higher than those obtained with the state-of-the-art homogeneous catalyst, AgNO3, under otherwise identical conditions. To the best of our knowledge, this represents the first true heterogeneous catalyst for the selective formation of C(sp3)-F bonds with electrophilic fluorine donors, representing a major breakthrough in the field of catalytic fluorination