Development of microbial and/or enzymatic systems for the valorization of lignocellulosic wastes

The future trend of white biotechnology is the seek of renewable resources for the production of goods, traditionally obtained from petrol. Shifting society’s dependence away from petroleum to renewable biomass resources is generally viewed as an important contribute to the development of a sustainable industrial society and the reduction of greenhouse gas emissions. Among the available resources that are exploitable for biofuel production, there are the residues coming from different human activities such as agriculture (i.e.: cereals straws), food processing-industry, forestry, green and organic fractions of urban wastes. Their exploitation can contribute to the reduction of the price of the bioethanol production process, raw materials being responsible of almost half of the total production cost. A further element contributing to soaring biofuels costs, is constituted by enzymes. Their use roughly doubles the cost of cellulosic ethanol production and lessens the economic advantages of using waste materials. A valide alternative to purified/commercial enzymes may be the direct production of the enzymes of interest on the lignocellulosic material to be converted through its microbial fermentation. At this purpose, a powerful technique is solid state fermentation (SSF). This fermentative technique reproduces conditions really close to the natural environment in which many higher filamentous fungi have evolved. These microorganisms can be exploited both for wastes pretreatment, for the removal of lignin and hemicellulose hydrolysis, and for the production of industrially relevant enzymes (oxidative as well as hydolytic activities) for further applications. As a matter of fact, lignocellulosic wastes may contain significant concentrations of soluble carbohydrates and inducers of enzyme synthesis ensuring efficient production of lignino-cellulolytic enzymes. In the present study the residues from tomato and apple processing were chosen as raw materials. On the other side, as conversion microorganisms, the two white rot fungi Pleurotus ostreatus and Trametes versicolor, were selected. Culture conditions were set up, allowing waste colonization and transformation. This study showed the good potential of tomato pomace as substrate for laccases production by P. ostreatus and T. versicolor SSF, considering that significant enzyme activity levels were achieved without any optimization of culture conditions, neither by nutrient addition nor by O2 enrichment. Furthermore, SSFs on tomato pomace hold enormous potential for protease production, giving activity levels higher than those reported for fungi typically considered as the best protease producers. A process of fungal SSF was developed on apple waste, identifying the parameters allowing fast substrate colonization by both fungi. It was shown that apple pomace induced high levels of xylanases, with P. ostreatus secreting higher levels than T. versicolor. Both P. ostreatus and T. versicolor secreted levels of laccase activities that are lower or comparable with those obtained on tomato pomace. T. versicolor was shown to produce Manganese peroxidase, even if at low levels. On this substrate, low levels of protease activity were obtained, for both microorganisms. Furthermore, both tomato and apple pomace SSFs were shown to be better systems than liquid culture for the production of high laccases levels by P. ostreatus. Moreover, as one of the most significant results of this study, the developed P. ostreatus SSF processes provide the production of two laccase isoforms not detected in any other liquid culture conditions analysed so far. Finally, a strategy for P. ostreatus xylanase enrichment was investigated. The first trials for the identification of xylanolytic enzymes allowed the identification of an α-galactosidase. This enzyme even though not involved in xylan main chain break-down, plays its role in the removal of galactose units from both galactomannans and arabinoxylans, acting as ancillar xylanolytic enzyme

Modern technologies in Endodontics

Abstract Aim In Endodontics, a complete chemo-mechanical cleansing of the root canal system is essential to achieving success, which is gained through adequate tridimensional obturation of the endodontic space. Materials and methods Today, thanks to modern technologies as Operative Microscope, ultrasonic tips, M-Wire Files, devices to activate irrigation and tridimensional obturation performed with thermo plasticized gutta-percha, satisfactory results can be obtained. Results This study shows all the technologies that are available today to increase the chemo-mechanical cleansing and obturation of the entire and complicated endodontic system. Conclusions The positive results highlighted by these clinical cases demonstrate how the use of modern technologies are essential to avoid iatrogenic injury, and guarantee, on the other hand, safe and reproducible results

Modern technologies in Endodontics

AbstractAimIn Endodontics, a complete chemo-mechanical cleansing of the root canal system is essential to achieving success, which is gained through adequate tridimensional obturation of the endodontic space.Materials and methodsToday, thanks to modern technologies as Operative Microscope, ultrasonic tips, M-Wire Files, devices to activate irrigation and tridimensional obturation performed with thermo plasticized gutta-percha, satisfactory results can be obtained.ResultsThis study shows all the technologies that are available today to increase the chemo-mechanical cleansing and obturation of the entire and complicated endodontic system.ConclusionsThe positive results highlighted by these clinical cases demonstrate how the use of modern technologies are essential to avoid iatrogenic injury, and guarantee, on the other hand, safe and reproducible results

Enhanced Water Splitting on Thin-film Hematite Photoanodes Functionalized with Lithographically Fabricated Au Nanoparticles

Iron oxide in its crystalline form (hematite, alpha-Fe2O3) is an interesting candidate as a photoanode material for photoelectrochemical cells, in spite of its non-optimal optoelectronic properties. We report here on the beneficial effect of Au nanodisks on the photocurrent of alpha-Fe2O3. Photoanodes consisting of ultra-thin alpha-Fe2O3 films lithographically functionalized with Au nanodisks of varying size were characterized and tested. We found a significant increase in photocurrent for the functionalized samples. The highest increase in incident photon-to-electron conversion efficiency is roughly one order of magnitude compared with a reference sample without Au nanodisks and was found for incident light of 420 nm in wavelength. A detailed understanding of the phenomena underlying such an increase in efficiency is crucial to fully exploit the beneficial effect of the metallic nanostructures. This would contribute to make Fe2O3 more competitive in the race for the development of a commercially viable device for water splitting

Soft nanostructuring of YBCO Josephson Junctions by phase separation

We have developed a new method to fabricate biepitaxial YBa2Cu3O(7-x) (YBCO) Josephson junctions at the nanoscale, allowing junctions widths down to 100 nm and simultaneously avoiding the typical damage in grain boundary interfaces due to conventional patterning procedures. By using the competition between the superconducting YBCO and the insulating Y2BaCuO5 phases during film growth, we formed nanometer sized grain boundary junctions in the insulating Y2BaCuO5 matrix as confirmed by high resolution transmission electron microscopy. Electrical transport measurements give clear indications that we are close to probing the intrinsic properties of the grain boundaries.Comment: 16 pages, 6 figure

Fungal solid state fermentation on agro-industrial wastes for acid wastewater decolourization in a continuous flow packed-bed bioreactor

This study was aimed at developing a process of solid state fermentation (SSF) with the fungi Pleurotus ostreatus and Trametes versicolor on apple processing residues for wastewater decolorization. Both fungi were able to colonize apple residues without any addition of nutrients, material support or water. P. ostreatus produced the highest levels of laccases (up to 9 U g-1 of dry matter) and xylanases (up to 80 U g-1 of dry matter). A repeated batch decolorization experiment was set up with apple residues colonized by P. ostreatus, achieving 50% decolorization and 100% detoxification after 24 h, and, adding fresh wastewater every 24 h, a constant decolorization of 50% was measured for at least 1 month. A continuous decolorization experiment was set up by a packed-bed reactor based on colonized apple residues achieving a performance of 100 mg dye L-1 day-1 at a retention time of 50

Qui gardera nos enfants? Les nounous et le mères: une enquête de Caroline Ibos

Sebbene il libro di Caroline Ibos sia stato pubblicato in Francia nel 2012, risulta tuttora attuale. A partire da un’attenta etnografia del rapporto asimmetrico tra madri bianche e nounous nere, il testo si interroga sulle problematiche legate alla globalizzazione della catena della cura nel capitalismo contemporaneo. L'autrice affronta temi urgenti anche per il nostro paese, dove le lavoratrici della cura sono sottoposte a lavori precari e sottopagati, imbricati nella "norma dell'amore".Although Caroline Ibos' book was published in France in 2012, it is still relevant today.  Starting from the ethnography of the asymmetrical relationship between white mothers and black nounous, the text reflects on the problem of the globalization of the care chain in contemporary capitalism. The author discusses urgent topics for our country, where care workers are subjected to precarious and underpaid work regimes, imbricated with the “norm of love”.&nbsp