Lignin conversion into high added-value products.

230 p.(eng.) 232 p. (eusk.)El agotamiento de los recursos fósiles y el alto impacto ambiental que supone la no biodegradabilidad que presentan los materiales poliméricos procedentes de estas fuentes han promovido la necesidad urgente de buscar recursos alternativos sostenibles y más respetuosos con el medio ambiente como son los biopolímeros. Entre ellos, la lignina parece ser una candidata prometedora para la fabricación de compuestos como productos químicos y materiales. Sin embargo, este biopolímero está poco explotado, probablemente debido a su comportamiento recalcitrante y a su compleja estructura química, pero su valorización es esencial para que las biorrefinerías sean económicamente competitivas.En este contexto, esta tesis se centró en la revalorización de la lignina para su conversión en compuestos de alto valor añadido como los hidrogeles. Para ello, primeramente se llevó a cabo la optimización de la síntesis de hidrogeles físicos basados en lignina. A continuación, se estudió el efecto de varios parámetros sobre las propiedades finales de los materiales sintetizados y, finalmente, se testó su aplicabilidad en múltiples campos. Los resultados mostraron la importancia de la selección de los componentes así como del procedimiento de síntesis, y destacaron los beneficios que aporta la adición de lignina. Además, estos materiales presentaron resultados prometedores en la adsorción de colorantes y en el suministro de fármacos, y algunos de ellos presentaron también propiedades antifúngicas, haciéndolos útiles en muchos sectores. No obstante, los análisis de biocompatibilidad han evidenciado la necesidad de mejorar algunas características de los hidrogeles para su uso en biomedicina

Impact of the lignin type and source on the characteristics of physical lignin hydrogels

[EN] Multiple natural polymers have been investigated for the synthesis of hydrogels to the present date, but lignin has demonstrated to be a promising one for this purpose for the multiple advantages it offers. Lignin can be isolated from lignocellulosic material such as nut shells, which are usually undervalued wastes, and would be a great step forward on circular economy. Thus, in the present work, lignin was extracted from almond and walnut shells following a single-step (delignification) and double-step (autohydrolysis and delignification) biorefinery scheme. After the chemical composition and structures of these lignins were determined, hydrogels were synthesized combining them with poly (vinyl alcohol) by the means of freeze-thawing cycles so as to study the influence of the different lignins on their final properties. Additionally, the last thawing cycle of the synthesis process was lengthened in order to confirm previous assumptions about its effect on the characteristics of the synthesized materials. The obtained results showed significant variation between the 8 lignin samples, especially in their purity, molecular weights and total phenolic contents. The variation on the lignins leaded to several hydrogel morphologies, which directly affected their properties, primarily their swelling capacity, glass transition temperatures and compression strengths. It was also demonstrated the great effect that the duration of the last thawing had on the morphology and, hence, on the characteristics of the obtained materials. The synthesized samples were successfully employed as dye adsorbents and the evaluation of their antifungal activity showed positive results in some of the samples, which could be applied for food packaging.The authors would like to acknowledge the financial support of the Department of Education of the Basque Government (IT1008-16). A. Morales would like to thank the University of the Basque Country (Training of Researcher Staff, PIF17/207). P. Gull ' on would like to acknowledge the Grants for the recruitment of technical support staff (PTA2019-017850-I) under the State Plan for Scientific and Technical Research and Innovation 2017-2020. The authors thank SGIker (UPV/EHU/ERDF, EU) for their technical and human support

Influence of lignin modifications on physically crosslinked lignin hydrogels for drug delivery applications

So far, the possibility of synthesizing hydrogels based on multiple biopolymers has been investigated, and among them lignin has proven to be one of the potentials for this purpose due to the multiple advantages it offers. However, because of its high molecular weight, steric hindrance and few reactive sites on its structure, it is sometimes necessary to improve its reactivity though chemical modifications. On the basis of previous results, two chemical modifications were selected in order to enhance almond, walnut and commercial alkaline and organosolv lignins' reactivity: a peroxidation reaction for alkaline ones and a hydroxymethylation for organosolv ones. Both reactions were confirmed by multiple techniques (i.e. FTIR, GPC and TGA). Hydrogels were syn-thesized from these lignins according to previous works. The high lignin waste of the synthesized hydrogels suggested that despite the modification of the lignins, just the highest molecular weight fractions reacted with the matrix polymer. Moreover, the swelling capacity of modified alkaline lignin-based hydrogels was negatively affected, whereas the one for organosolv lignin-based samples improved. The SEM micrographs explained the aforementioned, and the results from the DSC and compression tests were in accordance with them. Self -extracted quercetin loading and release studies suggested that these samples could be used for controlled drug delivery.The authors would like to acknowledge the financial support of the Department of Education of the Basque Government (IT1498-22) . A. Morales would like to thank the University of the Basque Country (Training of Researcher Staff, PIF17/207) . P. Gullón would like to acknowledge the Grants for the recruitment of technical support staff (PTA2019-017850-I) under the Spanish State Plan for Scientific and Technical Research and Innovation 2017-2020. The authors thank SGIker (UPV/EHU/ERDF, EU) for their technical and human support

Integral valorisation of walnut shells based on a three-step sequential delignification

[EN] Walnut kernels represent no more than 50-60% of the total weight of the fruit, so the sum of walnut shells generated every year is immense. Nonetheless, these shells could be further valorised for the extraction of their main constituents following a biorefinery scheme. Hence, the objective of this work was an integral valorisation of walnut shells, which involved a sequential organosolv delignification (200 ?, 90 min, 70/30 v/v EtOH/H2O, LSR 6:1) and several posterior non-isothermal hydrothermal treatments (180, 195 and 210 ?, LSR 8:1). Moreover, the spent solids after the aforementioned treatments were evaluated as possible sources of cellulose nanocrystals. The results showed that the sequential organosolv delignifications presented relative lignin yields up to 60%, which leaded to lignins that just differed on their molecular weight distributions. The hydrothermal treatments were efficient for the removal of still present hemicelluloses (14.7-71.8%), and permitted a successful cellulose nanocrystal obtaining whereas the spent solid from the delignification stages did not. Thus, this study presented an innovative strategy for the integral valorisation of walnut shells.The authors would like to thank the Department of Education of the Basque Government (IT1008-16) for the financial support. A. Morales would like to thank the University of the Basque Country (Training of Researcher Staff, PIF17/207). The authors would like to thank SGIker for the provided technical and human support (UPV/EHU/ERDF, EU)

Cross-Linked Carboxymethylcellulose Adsorbtion Membranes from Ziziphus lotus for the Removal of Organic Dye Pollutants

The goal of this study is to assess Ziziphus lotus’s potential for producing carboxymethylcellulose adsorption membranes with the ability to adsorb methyl green from wastewaters by the revalorization of its cellulosic fraction. The cellulose from this feedstock was extracted by an alkaline process and TAPPI standard technique T 203 cm-99 and afterwards they were carboxymethylated. The obtained carboxymethylcelluloses were deeply characterized, being observed that the carboxymethylcellulose produced from the alkaline cellulose presented the higher solubility due to its lower crystallinity degree (53.31 vs. 59.4%) and its higher substitution degree (0.85 vs. 0.74). This carboxymethylcellulose was cross-linked with citric acid in an aqueous treatment in order to form an adsorption membrane. The citric acid provided rigidity to the membrane and although it was hydrophilic it was not soluble in water. By evaluating the potential of the produced membrane for the removal of pollutant dyes from wastewater, it was observed that the adsorption membrane prepared from the carboxymethylcellulose’s produced from the Ziziphus lotus was able to remove 99% of the dye, methyl green, present in the wastewater. Thus, this work demonstrates the potential of the Ziziphus lotus for the production of a novel and cost-effective carboxymethylcellulose adsorption membrane with high capacity to treat wastewaters.This research was funded by Ministry of Higher Education and Scientific Research of Tunisia, I. Dávila would like to thank the University of the Basque Country (UPV/EHU) for their financial support (Grant reference DOCREC19/47)

Life Cycle Assessment of various biorefinery approaches for the valorisation of almond shells

In the near future, sustainable and efficient biorefineries would be essential for the production of commodity chemicals and high-added value compounds. Therefore, in this work, six scenarios differing on the delignification steps and cellulose conversion routes were assessed via Life Cycle Assessment methodology in order to study the environmental impacts derived from the conversion of an abundant agricultural residue (almond shells) into high added-value products and select the most suitable one for large-scale valorisation. The assessments were conducted employing experimental results and processing them by SimaPro software. The main conclusion achieved suggested that the enzymatic hydrolysis of the solid from any delignification step entailed the highest environmental impacts and had the highest relative contribution in all the studied impact categories with a maximum of 74%, which was ascribed to Scenario 5. It was also concluded that the organosolv delignification process affected overall more negatively than the alkaline treatment having bigger impacts especially in abiotic depletion (ADP) and photochemical oxidation (POP) categories. Finally, it can be stated that the best route for valorising the almond shell in a biorefinery facility is composed of autohydrolysis (common for every scenario), alkaline delignification, bleaching and acid hydrolysis steps for the obtaining of oligosaccharides, lignin and nanocrystals as products.Authors want to acknowledge the University of the Basque Country UPV/EHU, as well as the Spanish Ministry of Science and Innovation (CTQ2016-78689-R) for supporting financially this research. L.S. and R.F. would like to acknowledge the Departmentof Economic Development and Infrastructures of the Basque Government (scholarship of young researchers training) . A.M. and I.D, would like to thank the University of the Basque Country (Training of Researcher Staff, PIF17/207 and grant reference DOCREC19/47, respectively)

Evolving trends in the management of acute appendicitis during COVID-19 waves. The ACIE appy II study

Background: In 2020, ACIE Appy study showed that COVID-19 pandemic heavily affected the management of patients with acute appendicitis (AA) worldwide, with an increased rate of non-operative management (NOM) strategies and a trend toward open surgery due to concern of virus transmission by laparoscopy and controversial recommendations on this issue. The aim of this study was to survey again the same group of surgeons to assess if any difference in management attitudes of AA had occurred in the later stages of the outbreak. Methods: From August 15 to September 30, 2021, an online questionnaire was sent to all 709 participants of the ACIE Appy study. The questionnaire included questions on personal protective equipment (PPE), local policies and screening for SARS-CoV-2 infection, NOM, surgical approach and disease presentations in 2021. The results were compared with the results from the previous study. Results: A total of 476 answers were collected (response rate 67.1%). Screening policies were significatively improved with most patients screened regardless of symptoms (89.5% vs. 37.4%) with PCR and antigenic test as the preferred test (74.1% vs. 26.3%). More patients tested positive before surgery and commercial systems were the preferred ones to filter smoke plumes during laparoscopy. Laparoscopic appendicectomy was the first option in the treatment of AA, with a declined use of NOM. Conclusion: Management of AA has improved in the last waves of pandemic. Increased evidence regarding SARS-COV-2 infection along with a timely healthcare systems response has been translated into tailored attitudes and a better care for patients with AA worldwide

Evolving trends in the management of acute appendicitis during COVID-19 waves. The ACIE appy II study (vol 46, pg 2021, 2022)

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Clinical and genetic characteristics of late-onset Huntington's disease

Background: The frequency of late-onset Huntington's disease (>59 years) is assumed to be low and the clinical course milder. However, previous literature on late-onset disease is scarce and inconclusive. Objective: Our aim is to study clinical characteristics of late-onset compared to common-onset HD patients in a large cohort of HD patients from the Registry database. Methods: Participants with late- and common-onset (30–50 years)were compared for first clinical symptoms, disease progression, CAG repeat size and family history. Participants with a missing CAG repeat size, a repeat size of ≤35 or a UHDRS motor score of ≤5 were excluded. Results: Of 6007 eligible participants, 687 had late-onset (11.4%) and 3216 (53.5%) common-onset HD. Late-onset (n = 577) had significantly more gait and balance problems as first symptom compared to common-onset (n = 2408) (P <.001). Overall motor and cognitive performance (P <.001) were worse, however only disease motor progression was slower (coefficient, −0.58; SE 0.16; P <.001) compared to the common-onset group. Repeat size was significantly lower in the late-onset (n = 40.8; SD 1.6) compared to common-onset (n = 44.4; SD 2.8) (P <.001). Fewer late-onset patients (n = 451) had a positive family history compared to common-onset (n = 2940) (P <.001). Conclusions: Late-onset patients present more frequently with gait and balance problems as first symptom, and disease progression is not milder compared to common-onset HD patients apart from motor progression. The family history is likely to be negative, which might make diagnosing HD more difficult in this population. However, the balance and gait problems might be helpful in diagnosing HD in elderly patients