Inorganic materials as supports for covalent enzyme immobilization: Methods and mechanisms

Several inorganic materials are potentially suitable for enzymatic covalent immobilization, by means of several different techniques. Such materials must meet stringent criteria to be suitable as solid matrices: complete insolubility in water, reasonable mechanical strength and chemical resistance under the operational conditions, the capability to form manageable particles with high surface area, reactivity towards derivatizing/functionalizing agents. Non-specific protein adsorption should be always considered when planning covalent immobilization on inorganic solids. A huge mass of experimental work has shown that silica, silicates, borosilicates and aluminosilicates, alumina, titania, and other oxides, are the materials of choice when attempting enzyme immobilizations on inorganic supports. More recently, some forms of elemental carbon, silicon, and certain metals have been also proposed for certain applications. With regard to the derivatization/functionalization techniques, the use of organosilanes through silanization is undoubtedly the most studied and the most applied, although inorganic bridge formation and acylation with selected acyl halides have been deeply studied. In the present article, the most common inorganic supports for covalent immobilization of the enzymes are reviewed, with particular focus on their advantages and disadvantages in terms of enzyme loadings, operational stability, undesired adsorption, and costs. Mechanisms and methods for covalent immobilization are also discussed, focusing on the most widespread activating approaches (such as glutaraldehyde, cyanogen bromide, divinylsulfone, carbodiimides, carbonyldiimidazole, sulfonyl chlorides, chlorocarbonates, N-hydroxysuccinimides)

The coastal military architecture of World War II in Sardinia

[EN] After the Unification of Italy and after the First World War, the Stato Maggiore of the Royal Italian Army had to change the defence strategies and give more attention to coastal defence, because of the changing political relations and the development of military technology. In this overall strategic framework, the island of Sardinia was considered an "outpost of Italy", because of its defensive and offensive importance in the Mediterranean Sea. During World War II coastal defence became the operational priority of the Italian Army. In Sardinia, this was crucial for its proximity to Corsica and Tunisia and as a target of the Allies (after 1943). Consequently, substantial defence forces were introduced: army corps, brigades, mobile divisions, assault guns and gun trucks. The Army started to erect permanent fortification, in particular reinforced concrete structures produced designed according to standardized modules but adapted to the context using the means, resources and techniques available. Along the Sardinian coast, hundreds of bunkers were built and most of them are still existing in a state of neglect, sometimes in contexts of particular of great landscape and environmental value. This paper presents the systematic study of these "modern ruins built in concrete", through the examination of documents found in historical military archives and through a direct investigation of some of the most significant works. Also it offers a cataloguing through the categories of different disciplines (history, architecture, engineering, "Art of War" and ballistics) to encourage their enhancement and conservation, as architectural expression of a particular period of the 20th century history.Mameli, M.; Sanjust, P. (2015). The coastal military architecture of World War II in Sardinia. En Defensive architecture of the mediterranean: XV to XVIII centuries. Vol. II. Editorial Universitat Politècnica de València. 199-206. https://doi.org/10.4995/FORTMED2015.2015.1784OCS19920

Arborea. Le trasformazioni del paesaggio rurale

Il volume affronta da varie prospettive i tentativi e le esperienze di immigrazione che nel corso del tempo sono state progettate o attuate in Sardegna. Le vicende analizzate riguardano soprattutto le colonizzazioni avvenute nel corso del Novecento, anche se il saggio di apertura si sofferma sulle strategie di ripopolamento dell’Isola tentate dai governi piemontesi nel corso del Settecento e sul dibattito che, su questo tema, tornò ad essere vivace verso la metà del secolo XIX

Fungal laccases as tools for biodegradation of industrial dyes

Laccases are blue copper oxidases, found in some plants and secreted by a wide range of ligninolytic fungi. These enzymes are well known for their ability in oxidizing several organic compounds, mainly phenolics and aromatic amines, at the expenses of molecular oxygen. Therefore, they could find application in the field of enzymatic bioremediation of many industrial wastewaters, and in particular to bleach and/or detoxify dye-containing effluents. Not all industrial dyes behave as laccase substrates, but this limitation is often overcome by the judicious use of redox mediators. These could substantially widen the application range of laccases as bioremediation tools. The present study encompasses the main properties of the most used industrial dyes as related to their chemical classification, fungal laccases and their molecular and catalytic features, the use of redox mediators, limitations and perspectives of the use of fungal laccases for industrial dye bleaching

Evaluation of antioxidant capacity of antioxidant-declared beverages marketed in Italy

Clinical literature suggests a negative correlation between fruit juice consumption and the occurrence of various diseases. Consequently, many commercially available beverages are based on fruit juices or green tea extracts with specific additives that increase their antioxidant power. In order to fully estimate their potential antioxidant capacity, several products marketed in Italy were analyzed for total phenolics and flavonoids, DPPH scavenging activity, TEAC, FRAP and ORAC-PYR. On average, fruit-based samples had more antioxidants than green teas, but specific additives significantly improved total antioxidant power. Differences between these samples and plain fruit juices were also evaluated. Total antioxidant supply remained almost constant during the entire shelf life of the products

Muro Mediterráneo versus movimiento moderno

Una década antes de que fuera construido el Muro Atlántico fue ejecutado un sistema de defensas a lo largo de la costa del Mediterráneo español (1936-39). La recuperación de estas construcciones (de sus documentos gráficos) y su puesta en valor pueden ayudar a consolidar una memoria propia del siglo XX. Este trabajo consiste en inventariar, medir y dibujar los planos de estas arquitecturas a fin de fijar la memoria que se diluye por la erosión del tiempo. Estas defensas militares se sitúan en muchas fronteras: ¿son propiamente arquitectura o piezas industriales? ¿Son arquitectura moderna? Estas transitan entre dos mundos: uno que proyecta arquitecturas ligeras, flexibles y con caducidad frente a otro que construye obras compactas, rígidas y eternas. También se mueven por dos épocas: una que perpetúa las hazañas épicas frente a otras que muestra los desastres. Espacio, tiempo y materia. Son las ruinas de hormigón más modernas de nuestra historia que se encuentran camufladas en la topografía: templos y tumbas a la vez. En esta reconstrucción de la memoria, resulta crucial la restitución gráfica que es donde comienza el conocimiento

Immobilized lignin peroxidase-like metalloporphyrins as reusable catalysts in oxidative bleaching of industrial dyes

Synthetic and bioinspired metalloporphyrins are a class of redox-Active catalysts able to emulate several enzymes such as cytochromes P450, ligninolytic peroxidases, and peroxygenases. Their ability to perform oxidation and degradation of recalcitrant compounds, including aliphatic hydrocarbons, phenolic and non-phenolic aromatic compounds, sulfides, and nitroso-compounds, has been deeply investigated. Such a broad substrate specificity has suggested their use also in the bleaching of textile plant wastewaters. In fact, industrial dyes belong to very different chemical classes, being their effective and inexpensive oxidation an important challenge from both economic and environmental perspective. Accordingly, we review here the most widespread synthetic metalloporphyrins, and the most promising formulations for large-scale applications. In particular, we focus on the most convenient approaches for immobilization to conceive economical affordable processes. Then, the molecular routes of catalysis and the reported substrate specificity on the treatment of the most diffused textile dyes are encompassed, including the use of redox mediators and the comparison with the most common biological and enzymatic alternative, in order to depict an updated picture of a very promising field for large-scale applications

Pensado a mano: El aprendizaje a través del levantamiento del patrimonio arquitectónico moderno

La materia de la intervención en el patrimonio arquitectónico se nutre de discursos teóricos que tienen como puntos de partida y de destino la propia realidad. ¿Cómo podemos construir una estrategia donde las bases conceptuales encuentren su traslado a la actualidad? Una alternativa es la de trabajar sobre lo existente, más aún si este legado es moderno, cercano en el tiempo. Levantar el hecho arquitectónico, es decir, dibujarlo, es la primera acción para un conocimiento cierto, porque el dibujo ―que se procesa en las manos y pasa a ser tocado, sentido y calibrado― traslada el objeto del plano físico de lo concreto al plano mental de lo abstracto. Los dibujos, en tanto que pensamientos, permiten diseccionar los objetos y sugieren posibilidades ante un cambio de uso de cara al futuro para su supervivencia en tanto que patrimonio: arquitectura hecha en el pasado lista para ser usada y disfrutada en el futuro. La rehabilitación, la reutilización y el reciclaje de la herencia arquitectónica pasa por repensarse a mano, más que literalmente, como cualquier dibujo. Si toda intervención requiere de una investigación previa, toda idea de restauración necesita expresarse en el lenguaje gráfico

MicroRNA expression is associated with auditory dysfunction in workers exposed to ototoxic solvents and noise

This study is part of a project on early hearing dysfunction induced by combined exposure to volatile organic compounds (VOCs) and noise in occupational settings. In a previous study, 56 microRNAs were found differentially expressed in exposed workers compared to controls. Here, we analyze the statistical association of microRNA expression with audiometric hearing level (HL) and distortion product otoacoustic emission (DPOAE) level in that subset of differentially expressed microRNAs. The highest negative correlations were found; for HL, with miR-195-5p and miR-122-5p, and, for DPOAEs, with miR-92b-5p and miR-206. The homozygous (mut) and heterozygous (het) variants of the gene hOGG1 were found disadvantaged with respect to the wild-type (wt), as regards the risk of hearing impairment due to exposure to VOCs. An unsupervised artificial neural network (auto contractive map) was also used to detect and show, using graph analysis, the hidden connections between the explored variables. These findings may contribute to the formulation of mechanistic hypotheses about hearing damage due to co-exposure to noise and ototoxic solvents

Aflatoxin B1 and M1 Degradation by Lac2 from Pleurotus pulmonarius and Redox Mediators

Laccases (LCs) are multicopper oxidases that find application as versatile biocatalysts for the green bioremediation of environmental pollutants and xenobiotics. In this study we elucidate the degrading activity of Lac2 pure enzyme form Pleurotus pulmonarius towards aflatoxin B1 (AFB1) and M1 (AFM1). LC enzyme was purified using three chromatographic steps and identified as Lac2 through zymogram and LC-MS/MS. The degradation assays were performed in vitro at 25 °C for 72 h in buffer solution. AFB1 degradation by Lac2 direct oxidation was 23%. Toxin degradation was also investigated in the presence of three redox mediators, (2,2′-azino-bis-[3-ethylbenzothiazoline-6-sulfonic acid]) (ABTS) and two naturally-occurring phenols, acetosyringone (AS) and syringaldehyde (SA). The direct effect of the enzyme and the mediated action of Lac2 with redox mediators univocally proved the correlation between Lac2 activity and aflatoxins degradation. The degradation of AFB1 was enhanced by the addition of all mediators at 10 mM, with AS being the most effective (90% of degradation). AFM1 was completely degraded by Lac2 with all mediators at 10 mM. The novelty of this study relies on the identification of a pure enzyme as capable of degrading AFB1 and, for the first time, AFM1, and on the evidence that the mechanism of an effective degradation occurs via the mediation of natural phenolic compounds. These results opened new perspective for Lac2 application in the food and feed supply chains as a biotransforming agent of AFB1 and AFM1