SnO₂ nanoparticles in silica: nanosized tools for femtosecond-laser machining of refractive index patterns

We show that SnO2 nanoclusters in silica interact with ultrashort infrared laser pulses focused inside the material generating a hydrostatic compression and photoelastic response of the surrounding glass. This effect, together with the laser-induced nanocluster amorphization, gives rise to positive or negative refractive-index changes, up to 10–2, depending on the beam-power density. This result points out a wide tuning of the refractive index patterns obtainable in silica-based optical technology

Di racconti, ordine e legami. Primo Levi e la forma del Sistema periodico

The aim of this paper is to discuss a recent collection of Italian short stories: Racconti italiani scelti e introdotti da Jhumpa Lahiri."C’è una cosa che non mi stanco mai di dire a proposito del leggere racconti. I racconti non sono capitoli di un romanzo. Non vanno letti uno dopo l’altro, come se fossero stati composti in sequenza. Leggetene uno. Chiudete il libro. Leggete qualcos’altro. Riprendete il libro in mano dopo un po’ di tempo. I racconti sanno aspettare."Mavis Gallant sta qui ragionando su un certo tipo di raccolte di racconti, cioè quelle che accorpano testi che non hanno legami strutturali forti l’uno con l’altro: raccolte dove il collante tra le diverse storie non è un elemento caratterizzante. 

Can the fatty acids profile of Tuber aestivum - T. uncinatum species complex have chemotaxonomic value?

Fatty acid (FA) profiles are considered as chemotaxonomic markers to define groups of various taxonomic ranks in bacteria, yeasts, and fungi. Tuber aestivum is one of the most common European truffles that has environmental and economic values. While genetic studies suggest that T. aestivum Vittad. and T. uncinatum Chatin are synonymous, there is still debate over whether this is a species complex. In this work, we evaluate the differences in the total and individual FAs content of T. aestivum and T. uncinatum morphotypes, and T. melanosporum n-hexane extracts. The higher amounts of total linoleic acid and total oleic acid are found in T. uncinatum and characterize it from the T. aestivum. The composition of FA profiles of T. uncinatum-T. aestivum were distinguished by the presence of free palmitoleic acid (a chemotaxonomic marker) in T. uncinatum and absent in T. aestivum. Cluster analysis indicated that there were two groups for the FA profiles of the Tuber spp. hexanic extract: T. aestivum extract and T. uncinatum and T. melanosporum extracts. Our results indicate that T. aestivum and T. uncinatum have to be considered as two different taxa within the T. aestivum species complex

Exploring land use scenarios by long-term simulation of soil organic matter in central Argentina

Frequently, agriculture intensification by means of high-input technologies and agroecosystem simplification led to unsustainable farming systems. Increasing spatial-temporal diversity in agroecosystems has been shown as a promising alternative for restoring degraded land. A methodological approach is discussed here, based on preliminary results of experiences in a region of strong biophysical gradients. The CENTURY model is validated under local conditions and used as monitoring tool. The impact of an increased agrodiversity on soils with contrasting inherent properties is exemplified by running three land use scenarios for two case-study sites for the next 50 years and evaluating trends in soil organic matter (SOM) contents. Field survey and simulation results suggested that: (1) reference values for SOM levels for monitoring soil health should be defined considering main agroecological factors; (2) simulation models may help identifying adequate ranges of variation for them; (3) and model outputs may complement experimentation and represent a didactic tool to be used for decision-making and knowledge-transfer processes

Form birefringence anisotropic reflection and negative index change created by fs laser pulses in transparent materials

In recent years femtosecond lasers have proved to be of great utility for micromachining within the bulk of transparent materials

Multiple ligation of the proximal greater saphenous vein in the CHIVA treatment of primary varicose veins

Saphenous femoral disconnection is the key point of most surgical techniques in the treatment of primary varicose vein surgery. The aim of this study is to compare and analyze different techniques for conservative saphenousfemoral ligation or disconnection. These techniques can be to perform mini invasive open surgery and are suitable for implementation of the conservative hemodynamic correction of venous insufficiency (CHIVA) method. The aim was to present the follow-up by retrospective analysis of three different ligation-disconnection techniques of the proximal great saphenous vein (GSV) according to the CHIVA method at the GSV end, i.e. between the very end of the GSV and the first arch tributary, according to the CHIVA method. The first thecnique consisted of a surgical division (crossotomy). The other two consisted of triple superposed ligation with No. 2 non-absorbable braided coated suture without division labeled TSFL (triple saphenous flush ligation) and No. 0 polypropylenene ligation TPL (triple polypropylene ligation). The difference between TSFL and TPL was in the thickness and type of material of the thread, though both were non-absorbable. The follow up of 56 TPL procedures, 61 crossotomy procedures, and 82 TSFL procedures was analysed. The follow-up consisted of checking the sapheno-femoral junction occlusion with Duplex color ultra sound. The incidence rates of neovascularization (new vessels in the ligation or surgical disconnection site with saphenous-femoral reflux during the Valsalva maneuver) were: 4.9% for the crossotomy group, 6.1% for the TSFL group and 37.5% for the TPL group. The data analysed show satisfactory results with both crossotomy and TSFL. Crossotomy has proven to be an effective technique for performing saphenous-femoral disconnection, but TSFL could also be a reliable, safe and low-cost varicose mini-invasive surgery in outpatients. TPL appeared to be less reliable