Phase-space reconstruction of focused x-ray fields

We apply the method of phase-space tomography to reconstruct x-ray beams focused using a compound refractive lens. We show that it is possible to decouple the effect of aberrations in the optical system from the field and hence measure both them and the original field. We recover the complex coherence function and find that it is consistent with expectations.     

Experimental study of the separation behavior of nanoparticles in micro- and nanochannels

In this article, we investigate the effects of pH, ionic strength, and channel height on the mobility and diffusivity of charged spherical particles within planar microfluidic channels. Specifically, we report results of a broad experimental study on the transport and separation behavior of 50 and 100 nm spherical carboxylated polystyrene nanoparticles, confined in 20 μm, 1 μm, and 250 nm deep fluidic channels. We find that pH, ionic strength, and channel height have coupled impacts on mobility changes. In particular, we show that, depending on pH, the dependence of particle mobility on channel size can have opposing behavior. In addition, we also show that at the nanoscale, at lower ionic strengths, there is a substantial increase in mobility, due to enhanced electric fields within the nanochannels. These effects are important to understand in order to avoid potential downfalls in terms of separation efficiency as well as design for better tuning of separation performance in micro- and nanochannels. Finally, we propose a method to estimate the effective zeta potential of spherical particles from measured electrophoretic mobility data. This could prove useful in characterizing a heterogeneous collection of particles having a distribution over a range of values of the zeta potential.     

Cost Savings in Wastewater Treatment Processes: the Role of Environmental and Operational Drivers

In this study, 139 Tuscan Wastewater Treatment Plants (WWTPs) were analyzed with the aim of evaluating their efficiency and highlighting the main efficiency drivers, as well as distinguishing among wastewater features, WWTP technology, other features of WWTPs, output variables, and sludge disposal. From a methodological point of view, the proposed method includes an ordinary least squares analysis of total plant costs regressed on a set of 28 exogenous variables and a two-stage Data Envelopment Analysis model, where efficiency scores are obtained through weight restrictions. Moreover, the results of this study demonstrate that, with the exception of the “other features of WWTPs”, all other clusters of variables exert a negative effect on cost savings; in other words, larger scale of operations and higher usage of the productive capacity (grouped as “other features of WWTPs”) can improve cost efficiency.     

Exploring strategies for classification of external stimuli using statistical features of the plant electrical response

Plants sense their environment by producing electrical signals which in essence represent changes in underlying physiological processes. These electrical signals, when monitored, show both stochastic and deterministic dynamics. In this paper, we compute 11 statistical features from the raw non-stationary plant electrical signal time series to classify the stimulus applied (causing the electrical signal). By using different discriminant analysis-based classification techniques, we successfully establish that there is enough information in the raw electrical signal to classify the stimuli. In the process, we also propose two standard features which consistently give good classification results for three types of stimuli—sodium chloride (NaCl), sulfuric acid (H₂SO₄) and ozone (O₃). This may facilitate reduction in the complexity involved in computing all the features for online classification of similar external stimuli in future.     

Robust multiple cardiac arrhythmia detection through bispectrum analysis

This paper investigates the use of Higher Order Spectra parameters to identify the most common multiple cardiac arrhythmias. In detail, we calculated magnitude of bispectrum, three values of bispectrum entropy, mean and variance of the phase of bispectrum integrated over a particular region wherein no bispectrum aliasing is assumed. This set of features is used to distinguish normal QRS from five different classes of arrhythmia over a large amount of normal and pathologic ECG signals. An accurate parametric and non-parametric analysis of these feature distributions is also performed in order to identify the optimum classifier. Experimental tests were performed on signals gathered from the MIT-BIH Arrhythmias Database, and mean and standard deviation of all confusion matrixes obtained from 20 steps of cross validation are shown. Results showed that the bispectrum is high performance, reliable and robust method to identify arrhythmias.     

Marine Antimicrobial Peptides: Nature Provides Templates for the Design of Novel Compounds against Pathogenic Bacteria

The discovery of antibiotics for the treatment of bacterial infections brought the idea that bacteria would no longer endanger human health. However, bacterial diseases still represent a worldwide treat. The ability of microorganisms to develop resistance, together with the indiscriminate use of antibiotics, is mainly responsible for this situation; thus, resistance has compelled the scientific community to search for novel therapeutics. In this scenario, antimicrobial peptides (AMPs) provide a promising strategy against a wide array of pathogenic microorganisms, being able to act directly as antimicrobial agents but also being important regulators of the innate immune system. This review is an attempt to explore marine AMPs as a rich source of molecules with antimicrobial activity. In fact, the sea is poorly explored in terms of AMPs, but it represents a resource with plentiful antibacterial agents performing their role in a harsh environment. For the application of AMPs in the medical field limitations correlated to their peptide nature, their inactivation by environmental pH, presence of salts, proteases, or other components have to be solved. Thus, these peptides may act as templates for the design of more potent and less toxic compounds.     

Rapid Screening of Antioxidant Anthocyanins in Autochthonous Nero d’Avola Grape Clones by Pre-column DPPH Reaction Coupled to UHPLC-UV/Vis-IT-TOF: a Strategy to Combine Chemical data and Genetic Diversity

Grape is a rich source of bioactive compounds; among them anthocyanins are associated to many healthy properties, possessing a good antioxidant activity. In this work, we developed a fast and simple screening of antioxidant anthocyanins in six Sicilian Nero d’Avola autochthonous grape clones. The method was based on the pre-column reaction with 2,2′-diphenyl-1-picrylhydrazyl radical followed by the rapid separation by ultra high-pressure liquid chromatography coupled with ultraviolet and tandem mass spectrometry detection. Peak areas of antioxidant anthocyanins significantly reduced or even disappeared. The entire method took only 45 min per sample, showing good retention time and peak area repeatability with maximum CV% values ≤0.86 and 6.84, respectively. Samples rich in delphinidin derivatives showed lowest IC₅₀ values, since those compounds possess the highest scavenging ability. The developed setup was less complex than online approaches and faster with respect to conventional high-performance liquid chromatography methods, taking advantage of ultra high-performance conditions, coupled for the first time with pre-column 2,2′-diphenyl-1-picrylhydrazyl assay. The proposed strategy is a valid tool for a rapid screening of antioxidant anthocyanins in grape samples, useful to correlate the genetic diversity with the production of secondary metabolites as well to assess their activity in nutraceutical products rich in anthocyanins.     

Oxidative Alkoxycarbonylation of Alkynes by Means of Aryl α‐Diimine Palladium(II) Complexes as Catalysts

The straightforward in situ synthesized bis(2,6‐diisopropyl)acenaphthenequinonediimine palladium triflate catalyst was generally employed for both the mono‐alkoxycarbonylation of terminal alkynes, and the bis‐alkoxycarbonylation of 1,2‐disubstituted alkynes by using mild reaction conditions [carbon monoxide pressure (P_CO)=4 bar, temperature=20 °C]. Utilizing low catalyst loading (down to 0.5 mol%), a variety of propiolic esters were synthesized with good to excellent isolated yields. Most importantly the system was very efficient not only with methanol but also with a range of different alcohols, starting from the less hindered benzyl alcohol to the most hindered ones, such as isopropyl alcohol and tert‐butyl alcohol. In addition, aromatic and aliphatic 1,2‐disubstituted alkynes were converted into maleic acid derivatives, together with an acid‐catalyzed isomerization reaction, showing modest to good selectivity and excellent combined yields. In particular 3‐hexyne showed a satisfactory degree of selectivity for the maleic diesters of methanol and benzyl alcohol, obtaining the corresponding products with good isolated yields.

     

A deep knowledge of the behaviour of multi-component products for stone protection by an integrated analysis approach

The application of hydrophobic polymers to stone materials is an important treatment to preserve stone artefacts and protect cultural heritage from decay. To improve the characteristics and performance of water-repellent treatments, new solutions have been explored. In this research context, great attention has been paid to multi-component formulations that contain various monomers and copolymerise directly on stone. When they are obtained on inert rather than real substrates, such as stone, polymeric materials are often quite different in terms of their chemical and physical characteristics, polymerisation rate, and rheological properties. The stone's characteristics strongly influence its response to the application of conservation products; so different issues may be seen when applying the same treatment, depending on the interaction between the applied product and the stone support. Because of this, it is crucial to have the right tools to investigate how the substrate affects the monomers’ distribution of the applied mixtures and the resulting performance of the treatments. In this study, we followed an integrated approach based on the data collected by different analytical techniques (contact angle and colorimetric measurements, FT-IR analyses and ESEM-EDS analyses) to acquire a deeper knowledge of the behaviour of potential innovative water-repellents and their interaction with a stone support. This combined approach was used to evaluate the behaviour of methacrylate/vinyl-polysiloxane multi-component water-repellents applied on two calcareous stones displaying different microstructure and porosity: a compact limestone and a porous calcarenite.