Distribution of Relaxation Times Based on Lasso Regression: A Tool for High-Resolution Analysis of IMPS Data in Photoelectrochemical Systems.

Intensity-modulated photocurrent spectroscopy (IMPS) has been largely employed in semiconductor characterization for solar energy conversion devices to probe the operando behavior with widely available facilities. However, the implementation of IMPS data analysis to complex structures, whether based on the physical rate constant model (RCM) or the assumption-free distribution of relaxation times (DRT), is generally limited to a semi-quantitative description of the charge carrier kinetics of the system. In this study, a new algorithm for the analysis of IMPS data is developed, providing unprecedented time resolution to the investigation of µs to s charge carrier dynamics in semiconductor-based systems used in photoelectrochemistry and photovoltaics. The algorithm, based on the previously developed DRT analysis, is herein modified with a Lasso regression method and available to the reader free of charge. A validation of this new algorithm is performed on a α-Fe2O3 photoanode for photoelectrochemical water splitting, identified as a standard platform in the field, highlighting multiple potential-dependent charge transfer paths, otherwise hidden in the conventional IMPS data analysis.

Thiophene occurrence in different Tagetes species: agricultural biomasses as sources of biocidal substances.

BACKGROUND: Tagetes species produce thiophenes, polyacetylenic compounds that possess strong biocidal activity, thus making Tagetes plants very useful for suppressing nematode populations in the soil and as sources of natural pesticides. In the present study, Tagetes species (T. erecta, T. filifolia, T. lucida, T. minuta, T. patula and T. tenuifolia) grown in northern Italy were evaluated for their morphophenological parameters and thiophene pattern in different plant parts (roots, shoots and flowers). RESULTS: Roots had the highest diversity and contents of thiophenes (from 64 to 100% of the total thiophene amount), with 5-(3-buten-1-ynyl)-2,2'-bithienyl (BBT) as the main component followed by 5-(4-acetoxy-1-butynyl)-2,2'-bithienyl (BBTOAc), 2,2':5',2''-terthienyl (alpha-T) and 5-(4-hydroxy-1-butynyl)-2,2'-bithienyl (BBTOH). Tagetes lucida and T. tenuifolia possessed the highest amounts of total thiophenes (6717.3 and 6452.5 mg kg(-1) dry weight respectively), while T. minuta had the highest total thiophene yield (518.8 mg m(-2)), with BBT accounting for 98% of the total. CONCLUSION: Considering both thiophene concentrations and biomass yields, T. minuta and T. lucida appeared to be the most promising Tagetes species, with high potential for use as biocidal crops for the implementation of pest control practices that are less harmful to human health and natural resources.

Characterization and antimicrobial activity of essential oils of industrial hemp varieties (Cannabis sativa L.).

The present study focused on inhibitory activity of freshly extracted essential oils from three legal (THC<0.2% w/v) hemp varieties (Carmagnola, Fibranova and Futura) on microbial growth. The effect of different sowing times on oil composition and biological activity was also evaluated. Essential oils were distilled and then characterized through the gas chromatography and gas chromatography-mass spectrometry. Thereafter, the oils were compared to standard reagents on a broad range inhibition of microbial growth via minimum inhibitory concentration (MIC) assay. Microbial strains were divided into three groups: i) Gram (+) bacteria, which regard to food-borne pathogens or gastrointestinal bacteria, ii) Gram (-) bacteria and iii) yeasts, both being involved in plant interactions. The results showed that essential oils of industrial hemp can significantly inhibit the microbial growth, to an extent depending on variety and sowing time. It can be concluded that essential oils of industrial hemp, especially those of Futura, may have interesting applications to control spoilage and food-borne pathogens and phytopathogens microorganisms.