Characterization and valorization of lignocellulosic residues for applications in biomaterials

Abstract: Since ancient times, mankind has exploited natural resources to satisfy its needs such as food and clothes. With the discovery of fossil fuels (oil, gas, coal), mankind has improved his quality of life becoming more and more demanding. Nowadays, the unregulated use of oil has caused the current energy crisis and environmental problems, with greenhouse gas emissions that have reached worrying levels in our society. The increase of environmental pollution and climate changes, have made this resource unsustainable and no longer in line with the current development model: it is therefore necessary to find alternative sources of renewable energy. In this perspective, many renewable resources can be mentioned as the sun, the water, the wind, and the vegetal biomass. The latter is the most extensive, varied and readily available for the production of raw materials and energy; it offers the possibility, thanks to its chemical composition, to produce bio-energy and a wide range of bio-products. However, the growing demand for biomass and the strong competition with food resources, have led to the search for new vegetal species, not contrasting with food production, in accordance with the concept of sustainability. In this scenario, new perspectives for conventional and alternative oleaginous crops are open as renewable raw material for bio-based products, due to the possibility to use and valorize their products and co-products, in several industrial sectors. Among these, linseed (Linum usitatissimum L.) has gained considerable attention as a potential oilseed feedstock, due to its oil composition, and the interesting amounts of coproducts (lignocellulosic biomass), that can be valorized by converting them into bio-based products or within interesting applications as biocomposites materials, through the biorefinery processes, according to a cascading approach of full biomass utilization. The aim of this dissertation was to characterize and valorize the lignocellulosic residues of two varieties of linseed (Sidereal and Buenos Aires), grown under the pedo-climatic conditions of central Italy, where this species can represent a viable alternative for cropping system diversification. Therefore, the agronomic and qualitative evaluation has been carried out during 2014-2015 growing season at the Experimental Centre of the Department of Agriculture, Food and Environment (DAFE), University of Pisa. In particular, the following parameters were investigated: (i) quantification of the seed yield and lignocellulosic biomass; (ii) two stem pretreatments in order to obtain fibers from the lignocellulosic material; (iii) the morphological, chemical, and physical-mechanical evaluation of obtained fibers; (iv) the inclusion specimens of the fibers in composite materials and their general characteristics. The evaluation of fiber characteristics has been carried out in part at the DAFE laboratory (fiber extraction and chemical characteristics) and partly (morphological, and physical-mechanical fiber evaluation) at the Instituto de Ciência e Inovação em Engenharia Mecânica e Engenharia Industrial (INEGI) of the University of Porto (Portugal). The results obtained from the experimentation give an insight on the potential use of linseed fiber as reinforcement in biocomposites materials. In this work, it was demonstrated that the mechanical properties of the linseed fiber are virtually comparable with that of glass fiber, and that the biocomposites obtained may be used for the manufacturing on non-structural components. Riassunto: Fin dai tempi più antichi, l'uomo ha sfruttato le risorse naturali per soddisfare le sue esigenze come cibo e vestiti. Con la scoperta dei combustibili fossili (petrolio, gas, carbone), l’uomo ha migliorato la sua qualità di vita, diventando sempre più esigente e dipendente da tali fonti. Attualmente, l'uso non regolamentato di petrolio ha causato l'attuale crisi energetica e problemi ambientali e le emissioni di gas serra hanno raggiunto livelli preoccupanti nella nostra società. L'aumento dell'inquinamento ambientale e il cambiamento climatico, hanno reso questa risorsa insostenibile e non più in linea con l'attuale modello di sviluppo; si rende, quindi, necessario trovare fonti alternative di energia rinnovabile. In tal senso, si possono includere molte risorse rinnovabili come il sole, l'acqua, il vento e le biomasse di origine vegetale. Queste ultime rappresentano la risorsa più vasta, varia e prontamente disponibile per la produzione di materie prime e di energia, offrendo la possibilità, grazie alla particolare composizione chimica, di produrre una vasta gamma di bio-prodotti e di bio-energia. Tuttavia, la crescente domanda di biomassa di origine vegetale e la forte concorrenza con le risorse alimentari, hanno portato alla ricerca di nuove specie vegetali, non in contrasto con la produzione alimentare ed in conformità con il concetto di sostenibilità. In questo contesto, le colture oleaginose, sia tradizionali che alternative, possono rappresentare una materia prima interessante per la produzione di bio-prodotti, grazie alla possibilità di utilizzo e valorizzazione sia dei loro prodotti principali, che dei co-prodotti, in numerosi settori industriali. Tra queste, particolare attenzione è rivolta al lino da olio (Linum usitatissimum L.), come potenziale feedstock, sia per la composizione del suo olio che per la grande quantità di co-prodotti ottenibili (biomassa lignocellulosica), che possono essere valorizzati, convertendoli in prodotti a base vegetale ad elevato valore aggiunto (ad esempio materiali biocompositi), attraverso processi di bioraffineria, in accordo ad un approccio di utilizzazione a cascata dell’intera biomassa vegetale. Lo scopo di questo lavoro di tesi è stato la caratterizzazione e la valorizzazione dei residui ligno-cellulosici di due varietà di lino da olio (Sideral e Buenos Aires), coltivate in pieno campo nelle condizioni pedo-climatiche dell’Italia centrale, dove tale specie può rappresentare una valida alternativa nella diversificazione dei sistemi colturali cerealicoli. Pertanto, è stata condotta una valutazione agronomica e qualitativa delle due varietà, in prova presso il centro sperimentale del Dipartimento di Scienze Agrarie, Alimentari e Agro-ambientali (DiSAAA-a) dell’Università di Pisa, nella stagione 2014-2015. In particolare, sono stati analizzati: (i) resa in seme e residui lignocellulosici; (ii) due pretrattamenti degli steli per l’ottenimento delle fibre dal residuo lignocellulosico; (iii) valutazione morfologica, chimica e fisico-meccanica delle fibre; (iv) provini di inclusione delle fibre in materiali compositi e le loro caratteristiche generali. La valutazione qualitativa delle fibre è stata in parte svolta presso i laboratori del DiSAAA-a, ed in parte presso l’Instituto de Ciência e Inovação em Engenharia Mecânica e Engenharia Industrial (INEGI) dell’Università di Porto (Portogallo). I risultati ottenuti dalla sperimentazione evidenziano le buone proprietà meccaniche delle fibre del lino, praticamente comparabili con quelle della fibra di vetro, che ne consentono l’utilizzo come rinforzo in materiali biocompositi per la realizzazione di componenti non strutturali

CHARACTERIZATION OF LIGNOCELLULOSIC RESIDUES OF LINSEED FOR APPLICATION IN BIOMATERIALS

This work compares the chemical and physic-mechanical properties of the fibers obtained from linseed stems by using chemical and enzymatic retting, in order to exploit their possible application in biocomposites. The obtained results give new insights on the valuable properties of linseed fiber as a lowcost reinforcement component in biocomposites, leading to the diversification of linseed plant application

The Role of Imaging in COVID-19 Pneumonia Diagnosis and Management: Main Positions of the Experts, Key Imaging Features and Open Answers

: Lung imaging is widely involved in facing the coronavirus disease (COVID-19) pandemic. In fact, the COVID-19 infection may lead to a rapidly evolving and potentially fatal pneumonia. Moreover, computed tomography (CT) can be more sensitive than the COVID-19 reverse transcriptase-polymerase chain reaction test, especially at the beginning of the disease. Only patients with mild features consistent with COVID-19 infection, negative COVID-19 test, or positive COVID-19 test but at low risk for disease progression should avoid imaging. However, imaging becomes mandatory if respiratory symptoms worsen. A CT pattern classification has been designed to help both radiologists and clinicians. The typical pattern of COVID-19 is depicted by multifocal, bilateral, and peripheral ground-glass opacities (with or without consolidations or crazy paving) or findings of organizing pneumonia. Moreover, CT has demonstrated a prognostic role in patients with a diagnosis of COVID-19 pneumonia. Lung ultrasounds (LUS) are an emergent tool in the diagnosis of the disease. The adoption of LUS combined to chest X-rays in COVID-19 in pneumonia diagnosis is an interesting prospect that needs to be confirmed

Noninvasive ventilation and renal replacement therapy in do-not-intubate order critically ill patients: A brief report

Introduction: Multiple organ failure has been considered a contraindication for noninvasive ventilation (NIV). Materials and methods: We described the outcome of Do-not-Intubate (DNI) patients with acute respiratory failure, treated with NIV and, subsequently, necessitating renal replacement therapy (RRT). Results and discussion: Seven patients admitted to our Respiratory Intensive Care Unit, developed Acute Kidney Injury (AKI) during NIV treatment and received RRT for 12.8 \ub1 8 days together with NIV. All the patients but one, discontinued renal support because they regained a satisfactory urinary output; nevertheless mortality rate was high (71%). Conclusion: Our data suggest that RRT could be feasible together with NIV. RRT was associated with an acute improvement in renal function but did not modify the mortality rate

Clinical Outcomes according to Timing to Non Invasive Ventilation Initiation in COPD Patients with Acute Respiratory Failure: A Retrospective Cohort Study

Nighttime and non-working days are characterized by a shortage of dedicated staff and available resources. Previous studies have highlighted that patients admitted during the weekend had higher mortality than patients admitted on weekdays (“weekend effect”). However, most studies have focused on specific conditions and controversial results were reported. We conducted an observational, monocentric, retrospective cohort study, based on data collected prospectively to evaluate the impact of the timing of NIV initiation on clinical outcomes in COPD patients with acute respiratory failure (ARF). A total of 266 patients requiring NIV with a time gap between diagnosis of ARF and NIV initiation p = 0.003) at the time of NIV initiation. The rate of NIV failure (need for intubation and/or all-cause in-hospital death) was similar among three different scenarios: “daytime” vs. “nighttime”, “working” vs. “non-working days”, “nighttime or non-working days” vs. “working days at daytime”. Patients starting NIV during nighttime had a longer gap to NIV initiation compared to daytime (219 vs. 115 min respectively, p = 0.01), but this did not influence the NIV outcome. These results suggested that in a training center for NIV management, the failure rate did not increase during the “silent” hours

Effects of non-invasive respiratory supports on inspiratory effort in moderate-severe COVID-19 patients. A randomized physiological study

Rationale and objective: Various forms of Non-invasive respiratory support (NRS) have been used during COVID-19, to treat Hypoxemic Acute Respiratory Failure (HARF), but it has been suggested that the occurrence of strenuous inspiratory efforts may cause Self Induced Lung Injury(P-SILI). The aim of this investigation was to record esophageal pressure, when starting NRS application, so as to better understand the potential risk of the patients in terms of P-SILI and ventilator induced lung injury (VILI).Methods and measurements: 21 patients with early de-novo respiratory failure due to COVID-19, underwent three 30 min trials applied in random order: high-flow nasal cannula (HFNC), continuous positive airway pressure (CPAP), and non-invasive ventilation (NIV). After each trial, standard oxygen therapy was reinstituted using a Venturi mask (VM). 15 patients accepted a nasogastric tube placement. Esophageal Pressure (Delta Pes) and dynamic transpulmonary driving pressure (Delta PLDyn), together with the breathing pattern using a bioelectrical impedance monitor were recorded. Arterial blood gases were collected in all patients.Main results: No statistically significant differences in breathing pattern and PaCO2 were found. PaO2/FiO(2) ratio improved significantly during NIV and CPAP vs VM. NIV was the only NRS to reduce significantly Delta Pes vs. VM (-10,2 +/- 5 cmH20 vs -3,9 +/- 3,4). No differences were found in Delta PLDyn between NRS (10,2 +/- 5; 9,9 +/- 3,8; 7,6 +/- 4,3; 8,8 +/- 3,6 during VM, HFNC, CPAP and NIV respectively). Minute ventilation (Ve) was directly dependent on the patient's inspiratory effort, irrespective of the NRS applied. 14% of patients were intubated, none of them showing a reduction in Delta Pes during NRS.Conclusions: In the early phase of HARF due to COVID-19, the inspiratory effort may not be markedly elevated and the application of NIV and CPAP ameliorates oxygenation vs VM. NIV was superior in reducing Delta Pes, maintaining Delta PLDyn within a range of potential safety

Effects of high-flow nasal cannula in patients with persistent hypercapnia after an acute COPD exacerbation: a prospective pilot study

BACKGROUND: Persistent hypercapnia after COPD exacerbation is associated with excess mortality and early rehospitalization. High Flow Nasal cannula (HFNC), may be theoretically an alternative to long-term noninvasive ventilation (NIV), since physiological studies have shown a reduction in PaCO2 level after few hours of treatment. In this clinical study we assessed the acceptability of HFNC and its effectiveness in reducing the level of PaCO2 in patients recovering from an Acute Hypercapnic Respiratory Failure (AHRF) episode. We also hypothesized that the response in CO2 clearance is dependent on baseline level of hypercapnia. METHODS: Fifty COPD patients recovering from an acute exacerbation and with persistent hypercapnia, despite having attained a stable pH (i.e. pH > 7,35 and PaCO2 > 45 mmHg on 3 consecutive measurements), were enrolled and treated with HFNC for at least 8 h/day and during the nighttime RESULTS: HFNC was well tolerated with a global tolerance score of 4.0 ± 0.9. When patients were separated into groups with or without COPD/OSA overlap syndrome, the “pure” COPD patients showed a statistically significant response in terms of PaCO2 decrease (p = 0.044). In addition, the subset of patients with a lower pH at enrolment were those who responded best in terms of CO2 clearance (score test for trend of odds, p = 0.0038). CONCLUSIONS: HFNC is able to significantly decrease the level of PaCO2 after 72 h only in “pure” COPD patients, recovering from AHRF. No effects in terms of CO2 reduction were found in those with overlap syndrome. The present findings will help guide selection of the best target population and allow a sample size calculation for future long-term randomized control trials of HFNC vs NIV

Design and synthesis of potent antimalarial agents based on clotrimazole scaffold: exploring an innovative pharmacophore.

Identification of new molecular scaffolds structurally unrelated to known antimalarials may represent a valid strategy to overcome resistance of P. falciparum (Pf) to currently available drugs. We describe herein the investigation of a new polycyclic pharmacophore, related to clotrimazole, to develop innovative antimalarial agents. This study allowed us to discover compounds characterized by a high in vitro potency, particularly against Pf CQ-resistant strains selectively targeting free heme, which are easy to synthesize by low-cost synthetic strategies