Chitosan and postharvest decay of fresh fruit: Meta-analysis of disease control and antimicrobial and eliciting activities

Consumers are increasingly aware of the importance of regular consumption of fresh fruit in their diet. Since fresh fruit are highly sensitive to postharvest decay, several investigations focused on the study natural compounds alternative to synthetic fungicides, to extend their shelf life. A long list of studies reported the effectiveness of the natural biopolymer chitosan in control of postharvest diseases of fresh fruit. However, these findings remain controversial, with many mixed claims in the literature. In this work, we used random-effects meta-analysis to investigate the effects of 1% chitosan on (a) postharvest decay incidence; (b) mycelium growth of fungal pathogens Botrytis cinerea, Penicillium spp., Colletotrichum spp. and Alternaria spp.; and (c) phenylalanine ammonia-lyase, chitinase and β-1,3-glucanase activities. Chitosan significantly reduced postharvest disease incidence (mean difference [MD], −30.22; p < 0.00001) and in vitro mycelium growth (MD, −54.32; p  < 0.00001). For host defense responses, there were significantly increased activities of β-1,3-glucanase (MD, 115.06; p = 0.003) and chitinase (MD, 75.95; p < 0.0002). This systematic review contributes to confirm the multiple mechanisms of mechanisms of action of chitosan, which has unique properties in the natural compound panorama. Chitosan thus represents a model plant protection biopolymer for sustainable control of postharvest decay of fresh fruit.     

Effect of the mimic structure on the molecular recognition properties of molecularly imprinted polymers for ochratoxin A prepared by a fragmental approach

In this work the fragmental approach was used to prepare several molecularly imprinted ethylene dimethacrylate-co-methacrylic acid polymers with molecular recognition towards the mycotoxin ochratoxin A, with the aim of searching for simpler mimic templates than the well-known N-(4-chloro-1-hydroxy-2-naphthoylamido)-(l)-phenylalanine. The screening for binding of two different kinds of ochratoxin-related molecules was performed by HPLC analysis. Ochratoxin A and the mimic templates were eluted in acetonitrile–acetic acid (0.1% v/v) and the imprinting factor was measured for all the ligands on all the columns packed with the imprinted polymers. The experimental results show that changes to the amino acidic sub-structure or the presence/absence of a chlorine atom in position 4 on the naphthalene ring system does not affect the molecular recognition of ochratoxin A by the resulting imprinted polymer. On the contrary, the presence of the bulky naphthalene ring system in the mimic template seems to be necessary to preserve the molecular recognition of ochratoxin. This binding behavior was found to be compatible with in silico simulations of the complexation between some of the mimic templates and molecules of methacrylic acid. The use of the mimic template N-(1-hydroxy-2-naphthoylamido)-(L)-phenylalanine seems to represent a synthetically simple approach to the preparation of imprinted polymers with molecular recognition properties towards ochratoxin A.     

Assessment of the greenhouse gas emissions from cogeneration and trigeneration systems. Part II: Analysis techniques and application cases

This paper provides a set of specific examples to show the effectiveness of the trigeneration CO₂emission reduction (TCO₂ER) indicator proposed in the companion paper (Part I: Models and indicators) to assess the greenhouse gas (GHG) emission reduction from cogeneration and trigeneration systems. Specific break-even analyses are developed by introducing further indicators, with the aim of assessing the conditions for which different types of combined systems and conventional separate production systems are equivalent in terms of GHG emissions. The various emission indicators are evaluated and discussed for a number of relevant application cases concerning cogeneration and trigeneration solutions with different types of equipment. Scenario analyses are carried out to assess the possible emission reduction benefits from extended diffusion of cogeneration and trigeneration in regions characterized by different energy generation frameworks. The results strongly depend on the available technologies for combined production, on the composition of the energy generation mix, and on the trend towards upgrading the various generation systems. The numerical outcomes indicate that cogeneration and trigeneration solutions could bring significant benefits in countries with prevailing electricity production from fossil fuels, quantified by the use of the proposed indicators.     

New perspectives for the Barkhausen effect

The precise connections between the Barkhausen effect and non-equilibrium critical phenomena and self-organized criticality (SOC) have been strongly debated in the past few years. We review the recent theoretical studies of the Barkhausen effect and discuss their relevance to quantitatively understand the experiments. We compare the results of disordered spin models, micromagnetic equations, and models for rigid and flexible domain walls with experiments on amorphous and polycrystalline ferromagnetic alloys. In particular, we discuss the theoretical predictions for the critical exponents of the power law decay and for the cutoff of the avalanche distributions. We conclude that models based on the dynamics of a flexible domain wall are the most successful in explaining existing experimental data.     

Matrix modelling of small-scale trigeneration systems and application to operational optimization

Combined production of electricity, heat and cooling power in trigeneration represents a key option for the development of high-efficiency and cost-effective integrated energy systems. The complexity of the possible plant schemes calls for the adoption of general models handling multiple interconnected components and energy flows of various typologies. This paper presents a comprehensive input–output matrix approach aimed at modelling small-scale trigeneration equipment taking into account the interactions among plant components and external energy networks. Starting from the definitions of specific efficiency matrices for each plant component and from a matrix representation of the relevant interconnections, an overall efficiency matrix representing the whole plant is constructed. This construction is carried out by means of an original procedure, suitable for automatic and symbolic implementation, which, exploiting graph theory concepts, explores the tree formed by the backward paths from outputs to inputs. The proposed formulation maintains the separation among the individual energy vectors, each of which can be associated to its time-dependent price, providing the basic framework for formulating optimization problems concerning management of trigeneration systems within an energy market context. A numerical example referred to the optimal operation of a composite scheme with absorption and electric chillers is illustrated and discussed. The results obtained show the modelling effectiveness of the proposed matrix formulation.     

Immune parameters in female workers exposed to urban pollutants

Urban outside workers, such as traffic police, are daily exposed to air pollutants and psychosocial stressors: for these workers, the working environment corresponds to the living environment of the general population. Studies in the literature have shown that immune parameters could be affected by chronic exposure to various chemical pollutants. The aim of this study is to evaluate whether occupational exposure to urban pollutants can cause alterations in NK, IL-2, IFN-gamma and C3 plasma levels in female traffic police compared to a control group. After excluding subjects with the principal confounding factors, 86 female traffic police and 87 controls were matched by age, years of police work and habitual alcohol consumption. The distribution of NK values in female traffic police and controls was significantly different (p=0.000); NK values above the upper limit of the normal laboratory range were observed in 23 female traffic police and in 2 controls (p=0.000). IL-2 mean levels were higher in traffic police compared to controls, but the difference was not significant. The mean and the distribution of IFN-gamma values in female traffic police and controls were not different. C3 mean levels were higher in female traffic police versus controls, but the difference was not significant. Considering that the subjects with the principal confounding factors were excluded from the study and that female traffic police and controls were matched by the above-mentioned variables, our results suggest that chronic occupational exposure to low doses of chemical stressors, which may interact with and add to psychosocial ones, can affect both innate and adaptative immunity.     

Microwave‐Assisted Fast Cyclohexane Oxygenation Catalyzed by Iron‐Substituted Polyoxotungstates

Under microwave irradiation, iron‐substituted polyoxotungstates (Fe‐POMs) catalyze cyclohexane oxygenation to A/K oil with 90–95% selectivity, unmatched turnover frequencies (40–400 h⁻¹), and multi‐turnover regime (>1000 TON). Such a rapid reaction protocol allowed the screening of so‐called inorganic Fe‐synzymes with 1–4 nuclearity, including a family of Krebs‐type isostructural complexes. Product distribution, kinetic analysis, mechanistic probes and fitting calculations, are consistent with a radical chain oxidation propagated by Fe‐catalysed decomposition of organic peroxides which ultimately depends on the redox‐properties and structural arrangement of the iron moiety within the POM cage.     

Temporal determinization of mutating finite automata: Reconstructing or restructuring

A mutating finite automaton (MFA) is a nondeterministic finite automaton (NFA) that changes its morphology over discrete time by a sequence of mutations. This results in a sequence of NFAs, the initial NFA, and one mutated NFA for each mutation. Some application domains, including model-based diagnosis of discrete-event systems in artificial intelligence and model-based testing in software engineering, require temporal determinization of MFAs. Determinizing an MFA temporally means generating a deterministic finite automaton (DFA) that is equivalent to the mutated NFA as soon as a mutation occurs. Since, in computation time, the classical Subset Construction determinization algorithm may be less than optimal when applied to MFAs, a conservative algorithm is proposed, called Subset Restructuring, which, instead of constructing the new DFA from scratch based on the mutated NFA, generates the new DFA by updating the previous DFA based on the mutation occurred. Subset Restructuring is sound and complete, thereby yielding the same DFA generated by Subset Construction. Results from massive experimentation indicate the viability of Subset Restructuring, especially so when large MFAs change by small mutations.     

Size-dependent dissociation of small cobalt clusters on ultrathin NaCl films

Mass-selected anionic cobalt clusters of two different sizes (Co2 and Co13) were deposited onto ultrathin NaC1 films grown on an Au(111) substrate.Using scanning tunneling microscopy experiments and density functional theory simulations,we show that the deposited Co2 cluster dissociates and that the resulting Co atoms dope the NaCl surface by substituting Na ions.In contrast,the larger Co13 cluster does not dissociate and remains stable on top of the NaC1 film.The sizedependent fragmentation of clusters is an important aspect in the understanding of the chemical interaction between size-selected small aggregates of atoms and supporting surfaces.