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Photoablation is a physical process employed for the cleaning of artefacts. While several authors have reported investigations concerning the dependence of the effects induced on the material for different laser wavelengths, no similar investigations have been reported so far about the dependence on the pulse duration, in spite of its importance being recognised. In order to approach this issue and to optimise the interaction process on different materials, a new Q-switched Nd:YAG laser system with variable pulse width for cleaning applications was designed and built at the Quantum Electronics Institute in Florence. It provides an extended pulse duration in respect of the standard Q-switched regime, by means of interchangeable optical fibers in the resonator. The new laser allows to change the pulse duration in the range between tens and hundreds nanoseconds up to several microseconds. According to our experience the adjustment of the pulse duration in this range may avoid the possibility of strong mechanical forces and excessive heating in the substrate, as it has been observed with standard Nd:YAG laser systems. The laser may be proposed for an accurate cleaning in a variety of restoration problems and materials.

We determined the nonlinear Kerr refractive index (n2 of LiBaF3 and LiLuF4 undoped crystals, by means of Z-scan measurements at 1064 nm. These materials are suitable for Ce3+ doping to obtain broadband laser emission in the UV. These n2 values (2.0x10–16 and 1.5x10–16 cm2/W at 1064 nm, respectively) are important for the characterization of new optical materials in view of the development of high peak power laser oscillators and amplifiers.

Crop rotation is a common practice aimed at enhancing both plant disease suppression and crop productivity under open field condition. The objective of the present study was to evaluate the effects of tomato-wheat rotation on Fusarium wilt suppression and shoot growth on tomato in comparison to tomato monoculture. The following factors were determined and integrated through a transdisciplinary approach: (i) soil chemical parameters; (ii) abundance, composition, richness and diversity of soil fungal and bacterial communities; (iii) soil biochemical and enzymatic indicators; (iv) abundance of Fusarium oxysporum isolates in rhizosphere under tomato cultivation and evaluation of the pathogenicity of the isolates; (v) suppressive response of the bulk soil samples against a selected pathogenic strain of Fusarium oxysporum f. sp. lycopersici on tomato; and (vi) tomato shoot growth. The integrated approach included soil amplicon sequencing by metabarcoding analyses carried out by Illumina MiSeq platform in association with the standard procedure for soil analyses. In addition, the pathogenicity of F. oxysporum from the tomato rhizosphere and the suppressive response of the soil bulk to Fusarium wilt were performed by bioassays under greenhouse condition. The results showed that, if durum wheat was rotated with cherry tomato for at least four consecutive years, it had the following beneficial effects: (i) increased suppressive response of the bulk soil samples against F. oxysporum f. sp. lycopersici, (ii) decreased abundance of the F. oxysporum isolates in tomato rhizosphere, (iii) decreased pathogenicity of the F. oxysporum isolates, and (iv) increased tomato shoot growth. The increased abundance of certain microbial groups belonging to potential biocontrol agents against fusaria-related wilt including Bacillales (Bacillus and Paenibacillus), Pseudomonadales (Pseudomonas), Streptomycetales (Streptomyces), Eurotiales (Aspergillus and Penicillium) and Mortierellales (Mortierella), as well as the highest tomato shoot growth, coincided with the end of the second wheat rotation cycle. There were significant Spearman cross-correlations and two-way ANOVA interactions among the microbiome variables with the (i) soil chemical parameters, (ii) abundance and pathogenicity of the F. oxysporum isolates in tomato rhizosphere, (iii) soil suppression to Fusarium wilt, and (iv) tomato shoot growth. The results indicate that a soil managed under tomato-wheat rotation displays increased suppressive response against Fusarium wilt and improved shoot growth in tomato plants by changing the microbial composition and chemical parameters of the soil.