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In this article, we propose to explore the chemical interaction between Pseudosphinx tetrio L. and Allamanda cathartica L. using different analytical methods, including an innovative electrochemical approach (called electrochemical ecology) and multivariate analysis, and we investigate the potential antimicrobial effects (antibacterial and antifungal activities) of this interaction in order to gain a better understanding of their specific interaction. The analytical study presents a similar chemical profile between the leaves of healthy and herbivorous A. cathartica and the excretions of the caterpillars. The similar analytical profile of the leaves of A. cathartica and the excretions of P. tetrio, and the difference with the caterpillar bodies, suggests a selective excretion of compounds by the caterpillar. The measured antimicrobial activities support the physicochemical tests. The natural products found selectively in the excretions (rather than in the body) could explain the ability of P. tetrio to feed on this toxic Apocynaceae species.

Evidence by selected area diffraction patterns shows the successful preparation of large area (cm × cm) MoS2/graphene heterojunctions in coincidence of the MoS2 and graphene hexagons (superlattice). The electrodes of MoS2/graphene in superlattice configuration show improved catalytic activity for H2 and O2 evolution with smaller overpotential of +0.34 V for the overall water splitting when compared with analogous MoS2/graphene heterojunction with random stacking.

Misconceptions of chemistry and chemical engineering university students concerning instrumental analysis have been established from coordinated tests, tutorial interviews and laboratory lessons. Misconceptions can be divided into: (1) formal, involving specific concepts and formulations within the general frame of chemistry; (2) operational/topical, dealing with specific capabilities, problems and operations in chemistry; (3) methodological, associated to peculiar methods of analytical chemistry and data treatment; and (4) social, regarding the relation of analytical data with the social frame. Such misconceptions define a non-structured view of analytical methods, procedures and protocols related with analytical instrumentation. Instruments are frequently viewed as an autonomous, error-free black box providing non-structured data with no need of calibration or control, whereas weak relationships are established between data and aims along the analytical process. (Contains 7 tables and 8 figures.) [Financial support for this paper was provided by the University of Valencia research project "Desarrollo de herramientas para el diagnostico y evaluacion de errores conceptuales y metodologicos en la ensenanza de la Quimica instrumental."]

Pseudomonas aeruginosa is a leading cause of nosocomial bloodstream infections. The outcome of these infections depends on the virulence of the microorganism as well as host-related conditions and factors. The complement system plays a crucial role in defense against bloodstream infections. P. aeruginosa counteracts complement attack by recruiting Factor H (FH) that inhibits complement amplification on the bacterial surface. Factor H-related proteins (FHRs) are a group of plasma proteins evolutionarily related to FH that have been postulated to interfere this bacterial evasion mechanism. In this study, we demonstrate that FHR-3 competes with purified FH for binding to P. aeruginosa and identify EF-Tu as a common bacterial target for both complement regulator factors. Importantly, elevated levels of FHR-3 in human serum promote complement activation, leading to increased opsonization and killing of P. aeruginosa. Conversely, physiological concentrations of FHR-3 have no significant effect. Our findings suggest that FHR-3 may serve as a protective host factor against P. aeruginosa infections.

The voltammetric response of microparticulate deposits resulting from the evaporation of ethanolic extracts of leaves of Ginkgo biloba L. trees in contact with aqueous acetate buffer has been studied. Voltammetric data associated with the oxidation of polyphenolic secondary metabolites permits the discrimination of individuals by sex and age. Evaluation of age variation of reactivity with reactive oxygen species (ROS) was also described.

En este trabajo se presenta el estudio analítico llevado a cabo en un manuscrito bereber del siglo XVIII en el que se han podido caracterizar los materiales que se emplearon para su fabricación, tanto las fibras para la realización del soporte como las tintas roja y negra usadas para escribir, y el colorante utilizado para teñir el papel de la contrasolapa, añadida con posterioridad. La metodología multitécnica empleada incluye técnicas convencionales como microscopía óptica, FESEM-EDX y espectroscopia FTIR, combinadas con técnicas avanzadas de análisis, como son VIMP y FIB-FESEM-EDX, las cuales proporcionan información detallada de las muestras de forma nanoinvasiva.

Pseudomonas aeruginosa is an important human opportunistic pathogen responsible for a wide range of infections. The complement system is the main early host defense mechanism to control these infections. P. aeruginosa counteracts complement attack by binding Factor H (FH), a complement regulator that inactivates C3b, preventing the formation of the C3-convertase and complement amplification on the bacterial surface. Factor H-related proteins (FHRs) are a group of plasma proteins evolutionarily related to FH that have been postulated to interfere in this bacterial mechanism of resisting complement. Here, we show that FHR-1 binds to P. aeruginosa via the outer membrane protein OprG in a lipopolysaccharide (LPS) O antigen-dependent manner. Binding assays with purified components or with FHR-1-deficient serum supplemented with FHR-1 show that FHR-1 competes with FH for binding to P. aeruginosa. Blockage of FH binding to C3b deposited on the bacteria reduces FH-mediated cofactor activity of C3b degradation, increasing the opsonization of the bacteria and the formation of the potent chemoattractant C5a. Overall, our findings indicate that FHR-1 is a host factor that promotes complement activation, facilitating clearance of P. aeruginosa by opsonophagocytosis.

Pseudomonas aeruginosa is a common pathogen associated with recreational water facilities and poses risks to public health. However, data on the prevalence of P. aeruginosa in tourist destinations like the Canary Islands, Spain, remain limited. We assessed P. aeruginosa prevalence in 23 tourist facilities from 2016 to 2019. Compliance with water quality standards was evaluated, and 3962 samples were collected and analyzed. We examined different types of recreational water installations, including outer swimming pools, whirlpools, and cold wells. Of the sampled facilities, 31.2% did not comply with the current legislation’s parametric values, mainly due to inadequate disinfectant levels, water temperature, and P. aeruginosa presence. The prevalence of P. aeruginosa was 4.8%, comparable to some European countries but lower than others. Cold wells displayed the highest non-compliance rate (89.2%) and yet exhibited a lower P. aeruginosa prevalence (1.9%) than outer swimming pools and whirlpools. Children’s presence did not significantly impact P. aeruginosa contamination. Chlorine-based disinfectants are more effective than bromine-based ones in controlling P. aeruginosa. Regional variability in contamination was observed, with Fuerteventura showing lower colonization rates. Disinfectant levels play a critical role in P. aeruginosa control, and maintaining adequate levels is essential, particularly in bromine-treated installations. Our findings provide valuable insights into the prevalence and distribution of P. aeruginosa in recreational waters within tourist facilities. Tailored strategies are needed to ensure water safety in different Spanish regions. Continued monitoring and assessment, combined with artificial intelligence and machine learning, will enable the implementation of targeted interventions to protect the health of recreational water users.

Donor–acceptor-substituted biphenyl derivatives are particularly interesting model compounds, which exhibit intramolecular charge transfer because of the extent of charge transfer between both substituents. The connection of a 4-[1,1′-biphenyl]-4-yl-2-pyrimidinyl) moiety to differently disubstituted amino groups at the biphenyl terminal can offer push–pull compounds with distinctive photophysical properties. Herein, we report a comprehensive study of the influence of the torsion angle of the disubstituted amino group on the emissive properties of two pull–push systems: 4-[4-(4-N,N-dimethylaminophenyl)phenyl]-2,6-diphenylpyrimidine (D1) and 4-[4-(4-N,N-diphenylaminophenyl)phenyl]-2,6-diphenylpyrimidine (D2). The torsion angle of the disubstituted amino group, either N,N-dimethyl-amine or N,N-diphenyl-amine, at the biphenyl end governs their emissive properties. A drastic fluorescence quenching occurs in D1 as the solvent polarity increases, whereas D2 maintains its emission independently of the solvent polarity. Theoretical calculations on D1 support the presence of a twisted geometry for the lowest energy, charge-transfer excited state (S1,90), which corresponds to the minimum energy structure in polar solvents and presents a small energy barrier to move from the excited to the ground state, thereby favoring the non-radiative pathway and reducing the fluorescence efficiency. In contrast, this twisted structure is absent in D2 due to the steric hindrance of the phenyl groups attached to the amine group, making the non-radiative decay less favorable. Our findings provide insights into the crucial role of the substituent in the donor moiety of donor–acceptor systems on both the singlet excited state and the intramolecular charge-transfer process.

Cystic fibrosis (CF) disease is characterized by an intense airway inflammatory response mediated by neutrophils and chronic respiratory infections caused by P. aeruginosa. High levels of the complement component C5a, the strongest neutrophil chemoattractant molecule, are commonly found in the CF lung and have been associated with a worsening of the disease. In this study, we investigated how the isolates from CF patients modulate the levels of C5a and identified the bacterial factors involved. We demonstrated that most isolates from airway chronic infections induce the production and accumulation of C5a, an effect attributable to the loss of C5a cleavage by the exoproteases alkaline protease (AprA) and elastase B (LasB). Furthermore, we found that lack of the bacterial protease-dependent C5a degradation is due to mutations in the master regulator LasR. Thus, complementation of a non-C5a-cleaving CF isolate with a functional wild-type LasR restored its ability to express both proteases, cleave C5a and reduce neutrophil recruitment in vitro. These findings suggest that the non-cleaving C5a phenotype acquired by the LasR variants frequently isolated in CF patients may account for the strong neutrophilia and general neutrophil dysfunction predisposing toward increased inflammation and reduced bacterial clearance described in CF patients.

Background: Pseudomonas aeruginosa is a major opportunistic human pathogen commonly connected with recreational water activities. Spain is a tourist destination where most of the establishments have swimming pool. Nevertheless, the prevalence of P. aeruginosa in public swimming pools in our country is unknown. This works aimed to survey the P. aeruginosa presence in tourist Spanish recreational waters. Method: Tourist recreational water in hotels in the Balearic Islands were visited for four years (2016–2019). The levels of selected parameters were determined, and their correlation with P. aeruginosa contamination investigated. Results: We evaluated 11,014 samples from 254 facilities. Unacceptable levels of at least one legislated parameter were detected in 30.7% of cases, implicating closure in 15.9%, being P. aeruginosa the leading cause of closure. The prevalence of the pathogen was 14.2%, with lower presence in outer swimming pools. Disinfectant levels influence P. aeruginosa contamination, and bromine-maintained pools were more often contaminated than those treated with chlorine. Prevalence remained constant over the years, although it increased in 2019. Conclusions: P. aeruginosa prevalence in our recreational waters is similar to other countries, and the contamination rates depend on the installations and type and disinfectant levels. Corrective measures are still needed to improve pathogen control.

The in situ voltammetry of blueberry fruits and microparticulate deposits from their ethanolic extracts reveals the appearance of a prominent oxidation signal at ca. − 0.7 V vs. Ag/AgCl. This only appears in the presence of O2 under conditions in which the superoxide radical anion is generated initially. This feature, mainly associated with anthocyanins, is in agreement with SECM examination of blueberry thin epithelial films, and suggests that there is reactive oxygen species (ROS)-assisted promotion of the antioxidant capacity of anthocyanins accompanying the phenoxide-mediated ROS reactivity of these compounds.

The chain-walking of terminal alkenes is an industrially relevant reaction. Here, the authors show that part-per-million amounts of a variety of ruthenium compounds catalyze the reaction in yields and selectivity up to >99%, without any solvent or additive.

Swimming pools are a major contributor to water consumption in our community. However, the high water loss associated with filter cleaning is unknown. In this work, we investigate the current procedures for filter backwashing in public swimming pools by questionnaires to owners and managers. Then, we use the collected data to estimate their environmental and economic costs. Besides, we measure several parameters in the field during the process performed in four representative swimming pools. The investigation revealed that the water loss associated with filter cleaning in public swimming pools rises to 5.5 million m3 water per year, which represents an expense of 13.96 million €. Based on our results, the followed protocols were inappropriate in most cases, indicating that even the required water amount would be higher. The most suitable parameters for filter backwashing monitoring were combined chlorine, ammonium, turbidity and chemical oxygen demand (COD). The necessity for specific strategies and legislation for the management of these installations, the treatment of the generated wastewater, as the implementation of different technological solutions to reduce water loss are discussed. HIGHLIGHTS Water loss from filter backwashing in our community is huge.; Current filter backwashing practices are insufficient and should be improved.; The most suitable parameters for filter backwashing monitoring are combined chlorine, ammonium, turbidity and COD.; Official parameters and limits for backwashing monitoring are needed.; Water-saving strategies should include water reuse and technological improvements.;

Huanglongbing (HLB) is a disease that is responsible for the death of millions of trees worldwide. The bacterial causal agent belongs to Candidatus Liberibacter spp., which is transmitted by psyllids. The bacterium lead most of the time to a reaction of the tree associated with callose synthesis at the phloem sieve plate. Thus, the obstruction of pores providing connections between adjacent sieve elements will limit the symplastic transport of the sugars and starches synthesized through photosynthesis. In the present article, we investigated the impact of the use of tetraploid Swingle citrumelo (Citrus paradisi Macfrad × Poncirus trifoliata [L.] Raf) rootstock on HLB tolerance, compared to its respective diploid. HLB-infected diploid and tetraploid rootstocks were investigated when grafted with Mexican and Persian limes. Secondary roots were anatomically studied using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) to observe callose deposition at the phloem sieve plate and to evaluate the impact of the bacterium’s presence at the cellular level. Voltammetry of immobilized microparticles (VIMP) in roots was applied to determine the oxidative stress status of root samples. In the field, Mexican and Persian lime leaves of trees grafted onto tetraploid rootstock presented less symptoms of HLB. Anatomical analysis showed much stronger secondary root degradation in diploid rootstock, compared to tetraploid rootstock. Analysis of the root sieve plate in control root samples showed that pores were approximately 1.8-fold larger in tetraploid Swingle citrumelo than in its respective diploid. SEM analyses of root samples did not reveal any callose deposition into pores of diploid and tetraploid genotypes. VIMP showed limited oxidative stress in tetraploid samples, compared to diploid ones. These results were even strongly enhanced when rootstocks were grafted with Persian limes, compared to Mexican limes, which was corroborated by stronger polyphenol contents. TEM analysis showed that the bacteria was present in both ploidy root samples with no major impacts detected on cell walls or cell structures. These results reveal that tetraploid Swingle citrumelo rootstock confers better tolerance to HLB than diploid. Additionally, an even stronger tolerance is achieved when the triploid Persian lime scion is associated.

The increasing emergence of multidrug resistant isolates of P. aeruginosa causes major problems in hospitals worldwide. This concern is particularly significant in bloodstream infections that progress rapidly, with a high number of deaths within the first hours and without time to select the most appropriate treatment. In fact, despite improvements in antimicrobial therapy and hospital care, P. aeruginosa bacteremia remains fatal in about 30% of cases. The complement system is a main defensive mechanism in blood against this pathogen. This system can mark bacteria for phagocytosis or directly lyse it via the insertion of a membrane attack complex in the bacterial membrane. P. aeruginosa exploits different strategies to resist complement attack. In this review for the special issue on “bacterial pathogens associated with bacteriemia”, we present an overview of the interactions between P. aeruginosa and the complement components and strategies used by this pathogen to prevent recognition and killing by the complement system. A thorough understanding of these interactions will be critical in order to develop drugs to counteract bacterial evasion mechanisms.

Malaria is one of the most widespread parasitic diseases, especially in Africa, Southeast Asia and South America. One of the greatest problems for control of the disease is the emergence of drug resistance, which leads to a need for the development of new antimalarial compounds. The biosynthesis of isoprenoids has been investigated as part of a strategy to identify new targets to obtain new antimalarial drugs. Several isoprenoid quinones, including menaquinone-4 (MK-4/vitamin K2), α- and γ-tocopherol and ubiquinone (UQ) homologs UQ-8 and UQ-9, were previously detected in in vitro cultures of Plasmodium falciparum in asexual stages. Herein, we described for the first time the presence of phylloquinone (PK/vitamin K1) in P. falciparum and discuss the possible origins of this prenylquinone. While our results in metabolic labeling experiments suggest a biosynthesis of PK prenylation via phytyl pyrophosphate (phytyl-PP) with phytol being phosphorylated, on the other hand, exogenous PK attenuated atovaquone effects on parasitic growth and respiration, showing that this metabolite can be transported from extracellular environment and that the mitochondrial electron transport system (ETS) of P. falciparum is capable to interact with PK. Although the natural role and origin of PK remains elusive, this work highlights the PK importance in plasmodial metabolism and future studies will be important to elucidate in seeking new targets for antimalarial drugs.

Abstract The degradation of laboratory oil paint film specimens containing indigo and Prussian blue pigments and pictorial samples from the Sant Francesc de Paula painting exhibited in the Tomàs Balvey Arxiu Museum (Cardedeu (Catalonia), Spain) has been studied by voltammetry of immobilized particles. This technique, combined with light microscopy, scanning electron microscopy-energy dispersive X-ray analysis, nanoindentation-atomic force microscopy, attenuated total reflectance-Fourier-transform infrared spectroscopy and gas chromatography–mass spectroscopy techniques permits the proposal of a dual scheme for the degradation of the pigments when naturally aged and submitted to accelerated UVA aging. Under conditions of moderate temperature, humidity and natural illumination, and low gradients of these parameters, Prussian blue acts as a radical scavenger moderating the production of reactive oxygen species produced in the oil binding medium by the action of ultraviolet radiation, resulting in the formation, in the solid state, of the solid-solution, {KFeIII[FeII(CN)6]} x {FeIII[FeIII(CN)6]}1–x , known as Berlin green, which then promotes the formation of indigo adducts with radicals. In several localized areas of the Sant Francesc de Paula paint showing strong degradation, Prussian blue acts as a promoter of the indigo oxidation to isatin, thus resulting in a considerable chromatic shift.

Abstract The pigments were important in the funerary customs of the ancient Maya. They could be introduced as an offering inside the tombs or burials, and were also used to wrap the dead bodies, as if it were a funeral shroud. In the tombs and burials of royalty and high social classes the use of pigments for this purpose is well documented, and physicochemical studies are focused on their identification. This scientific contribution shows the results obtained when analyzing two reddish pigmenting materials from the grave goods of the tomb 19 of the archaeological site of Rio Azul, (Guatemalan Department of Petén), using a multi-technique approach including microscopy, diffraction, spectroscopic, electrochemical and chromatographic techniques. The results have enabled the identification of the inorganic and organic materials composing these pigmenting materials found in a ceramic posthumous offering dish and further discussion mainly has been focused on the geological source of the inorganic materials and the possible origin of the organic matter accompanying these two pigmenting materials.

Pseudomonas aeruginosa is a major cause of nosocomial bloodstream infections. This microorganism secretes two major proteases, alkaline protease A (AprA) and elastase B (LasB). Despite several in vitro studies having demonstrated that both purified proteases cleave a number of components of the immune system, their contribution to P. aeruginosa bloodstream infections in vivo remains poorly investigated. In this study, we used a set of isogenic mutants deficient in AprA, LasB or both to demonstrate that these exoproteases are sufficient to cleave the complement component C3, either soluble or deposited on the bacteria. Nonetheless, exoprotease-deficient mutants were as virulent as the wild-type strain in a murine model of systemic infection, in Caenorhabditis elegans and in Galleria mellonella. Consistently, the effect of the exoproteases on the opsonization of P. aeruginosa by C3 became evident four hours after the initial interaction of the complement with the microorganism and was not crucial to survival in blood. These results indicate that exoproteases AprA and LasB, although conferring the capacity to cleave C3, are not essential for the virulence of P. aeruginosa bloodstream infections.

Phage lysins are a promising alternative to common antibiotic chemotherapy. However, they have been regarded as less effective against Gram-negative pathogens unless engineered, e.g., by fusing them to antimicrobial peptides (AMPs). AMPs themselves pose an alternative to antibiotics. In this work, AMP P87, previously derived from a phage lysin (Pae87) with a presumed nonenzymatic mode-of-action, was investigated to improve its antibacterial activity. Five modifications were designed to maximize the hydrophobic moment and net charge, producing the modified peptide P88, which was evaluated in terms of bactericidal activity, cytotoxicity, MICs or synergy with antibiotics. P88 had a better bactericidal performance than P87 (an average of 6.0 vs. 1.5 log-killing activity on Pseudomonas aeruginosa strains treated with 10 µM). This did not correlate with a dramatic increase in cytotoxicity as assayed on A549 cell cultures. P88 was active against a range of P. aeruginosa isolates, with no intrinsic resistance factors identified. Synergy with some antibiotics was observed in vitro, in complex media, and in a respiratory infection mouse model. Therefore, P88 can be a new addition to the therapeutic toolbox of alternative antimicrobials against Gram-negative pathogens as a sole therapeutic, a complement to antibiotics, or a part to engineer proteinaceous antimicrobials.

Metal phosphides have recently emerged as promising electrocatalysts for hydrogen evolution reaction (HER). Herein, we report the synthesis of ruthenium diphosphide embedded on a dual-doped graphitic carbon by pyrolyzing chitosan beads impregnated with ruthenium chloride and phosphorus pentoxide. The as-synthesized RuP2@N-P-C displays a good electrocatalytic activity in acidic, neutral and alkaline media. We show that the HER activity of the electrocatalyst can be tuned by varying the concentration of Li+ cations. Co-diffusion effects on H+ exerted by Li+ on HER in the porous carbon matrix have been observed.

Este trabajo presenta un estudio del estado de conservación de monedas con base de cobre procedente del Museo Nacional de Arqueología Subacuática. La metodología multitécnica incluye instrumentación convencional como microscopía óptica, espectroscopia FTIR y técnicas avanzadas nanoinvasivas como voltamperometría de micropartículas y haz de iones focalizados-FESEM-EDX. Así se ha podido identificar el tipo de aleación, productos de corrosión, depósitos superficiales y antiguas intervenciones. Cabe señalar la identificación de mecanismos de alteración atípicos como la formación de complejos carboxilados de iones metálicos generados en los procesos electroquímicos de corrosión del metal o aleación y los materiales lipídicos fijados en la superficie de la moneda cuando esta estuvo en circulación y que gracias a su carácter hidrófobo se han conservado en el ambiente subacuático en el que las monedas han permanecido durante siglos. Estos hallazgos han resultado de gran utilidad para establecer los tratamientos más idóneos de conservación de estas piezas.

Group 15 elements in zero oxidation state, also called pnictogens, are rarely used in catalysis due to the difficulties in preparation. Here, the authors report on the synthesis of highly exfoliated, few layer 2D phosphorene and antimonene in zero oxidation state, and their use as efficient catalysts for the alkylation of nucleophiles with esters.

Agrobiodiversity and adaptability to environmental changes derived from global warming are challenges for the future of agriculture. In this sense, landraces often have high levels of genetic variation, tightly connected with the changing environmental conditions of a territory. The genus Phaseolus, with five domesticated species, is one of the most important sources of proteins, carbohydrates and micronutrients in various countries. This study aimed to compare the adaptation capacity to drought, in the vegetative growth phase, of a commercial cultivar and two landraces traditionally cultivated in the Mediterranean basin of Phaseolus lunatus (Lima bean). Growth and biochemical responses of the analysed genotypes to different water-deficit treatments were evaluated and compared. In addition, the effectiveness of the voltammetric method for evaluating stress levels in cultivated plants was tested. The studied parameters revealed that P. lunatus is a drought-tolerant species, showing similar results for the three cultivars. However, contrary to what was expected from the germination phase results, the commercial variety Peru showed some better responses under water stress conditions. Finally, the voltammetric method proved to be a good and fast tool for assessing oxidative stress in cultivated plants, showing results in agreement with total phenolic compounds and total flavonoid fluctuations.

Cortaderia selloana is an invasive, gynodioecious species prevalent in Mediterranean area which contains both female and hermaphrodite specimens in the wild population. Using voltammetric data we show that the female and hermaphrodite specimens exhibit differential electrochemical response. Cortaderia selloana leaves from two different provenances in the Valencia Mediterranean area, Sueca and Cullera (Comunitat Valenciana, Spain), in the surroundings of the Albufera Natural Park, a peculiar ecosystem containing unspoilt dune beaches and forests, were studied to determine correlation of flower morphology with the plant's ability to adapt to stress conditions. Our data suggests that gynodioecy may contribute to increasing versatility in the plant under stress by efficiently neutralizing reactive oxygen species (ROS). Keywords: Electrochemistry, Invasive species, Cortaderia, Gynodioecy, Reactive oxygen species

A methodology for monitoring the corrosion state of archaeological iron objects using ‘dry’ open circuit potential (OCP) measurements is described. Application of this technique to a set of objects from La Bastida de les Alcusses archaeological site (Moixent, València, Spain), dating back to the 4th century BCE, reveals significant differences depending on the conservation state. The transient OCP responses (which last between a few seconds and 10–15 min) were superimposed with much shorter (less than one second) intense features.

Abstract A set of ancient Antoninianus silver coins, dating back between 249 and 274 A.D. and minted in Rome, Galliae, Orient and Ticinum, have been characterized. We use, for the first time, a combination of nano-invasive (focused ion beam-field emission scanning electron microscopy-X-ray microanalysis (FIB-FESEM-EDX), voltammetry of microparticles (VIMP)) and destructive techniques (scanning electron microscopy (SEM-EDX) and electron microprobe analysis (EMPA)) along with non-invasive, i.e., micro-Raman spectroscopy. The results revealed that, contrary to the extended belief, a complex Ag-Cu-Pb-Sn alloy was used. The use of alloys was common in the flourishing years of the Roman Empire. In the prosperous periods, Romans produced Ag-Cu alloys with relatively high silver content for the manufacture of both the external layers and inner nucleus of coins. This study also revealed that, although surface silvering processes were applied in different periods of crisis under the reign of Antoninii, even during crisis, Romans produced Antoninianus of high quality. Moreover, a first attempt to improve the silvering procedure using Hg-Ag amalgam has been identified.

In order to determine the organic matter redox state in relation to specific sources in mangrove sediments, two 60 cm-long sediment cores were collected from mangrove-covered and mudflat zones within a mangrove forest in Peru. Sediment subsamples from these cores were analyzed to determine δ13C values and C:N ratios, whereas two redox indices, namely, electrochemical (fEAOM) and spectroscopical (A1650/A3400) indices, were taken from a previous study and correlated with the geochemical indices obtained from this work. These indices may provide accurate information on sedimentary organic matter diagenesis by oxidative processes through its redox state. The results show that the electrochemical index (fEAOM) and the spectroscopical index (A1650/A3400) for mangrove-covered sediments exhibited a positive correlation with δ13C values and a negative correlation with C:N molar ratios. These correlations suggest that the more labile sedimentary organic matter derived from non-terrestrial sources is in a more oxidized state than that derived from mangrove vegetation. However, this was not valid for mudflat zones, where non-significant correlations between geochemical indices were observed. Furthermore, the results suggest that the redox state of the organic matter deposited over time is dependent on source mixing influences, being better preserved in the presence of mangrove-derived organic matter.