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Healthcare workers experienced high degree of stress during COVID-19. Purpose of the present article is to compare mental health (depressive and Post-Traumatic-Stress-Disorders—PTSD—symptoms) and epigenetics aspects (degree of methylation of stress-related genes) in front-line healthcare professionals versus healthcare working in non-COVID-19 wards. Sixty-eight healthcare workers were included in the study: 39 were working in COVID-19 wards (cases) and 29 in non-COVID wards (controls). From all participants, demographic and clinical information were collected by an ad-hoc questionnaire. Depressive and PTSD symptoms were evaluated by the Patient Health Questionnaire-9 (PHQ-9) and the Impact of Event Scale—Revised (IES-R), respectively. Methylation analyses of 9 promoter/regulatory regions of genes known to be implicated in depression/PTSD (ADCYAP1, BDNF, CRHR1, DRD2, IGF2, LSD1/KDM1A, NR3C1, OXTR, SLC6A4) were performed on DNA from blood samples by the MassARRAY EpiTYPER platform, with MassCleave settings. Controls showed more frequent lifetime history of anxiety/depression with respect to cases (χ2 = 5.72, p = 0.03). On the contrary, cases versus controls presented higher PHQ-9 (t = 2.13, p = 0.04), PHQ-9 sleep item (t = 2.26, p = 0.03), IES-R total (t = 2.17, p = 0.03), IES-R intrusion (t = 2.46, p = 0.02), IES-R avoidance (t = 1.99, p = 0.05) mean total scores. Methylation levels at CRHR1, DRD2 and LSD1 genes was significantly higher in cases with respect to controls (p p = 0.03 and p = 0.03, respectively). Frontline health professionals experienced more negative effects on mental health during COVID-19 pandemic than non-frontline healthcare workers. Methylation levels were increased in genes regulating HPA axis (CRHR1) and dopamine neurotransmission (DRD2 and LSD1), thus supporting the involvement of these biological processes in depression/PTSD and indicating that methylation of these genes can be modulated by stress conditions, such as working as healthcare front-line during COVID-19 pandemic.

Geographical origin and authenticity of food are topics of interest for both consumers and producers. Among the different indicators used for traceability studies, n(87Sr)/n(86Sr) isotopic ratio has provided excellent results. In this study, the production chains of the balsamic vinegars of the Modena province, the Aceto Balsamico Tradizionale di Modena (ABTM) and the industrially made Aceto Balsamico di Modena (ABM) were investigated by using the n(87Sr)/n(86Sr) indicator. The geographical origin of the starting raw materials for the ABM production was investigated, as well as the variability of ABM samples of different production years, namely 2009, 2010, 2011 and 2014. The results show no significant variability among ABM samples of different production years and highlight the possibility to distinguish this product from the ABTM. Furthermore, the investigated indicator also confirms an objective link of the food with its starting raw material and the territory of origin of the grapes, assessing the discriminating power of n(87Sr)/n(86Sr) ratio for geographical traceability studies.

The metal content in some samples of horse chestnut seeds (Aesculus hippocastanum) was monitored over time (years 2016&ndash, 2019) considering the two most common and representative Mediterranean varieties: the pure species (AHP, which gives white flowers) and a hybrid one (AHH, which gives pink flowers). The selected elemental composition of the samples was determined by applying the Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES) technique. Several samples obtained from different preliminary treatments of the peeled seeds were examined, such as: (i) floury samples (wild-type) mineralized with the wet method, (ii) the ashes of both AHP and AHH varieties, (iii) the fraction of total inorganic soluble salts (TISS). Furthermore, the hydroalcoholic crude extracts (as a tincture) were obtained according to the official Pharmacopoeia methods, and the relevant results were compared with those of a commercial sample, an herbal product-food supplement of similar characteristics. The main characteristics of this research work underline that the two botanical varieties give different distinctive characters, due to the Fe content (80.05 vs. 1.42 mg/100 g d.s., for AHP and AHH wild-type flour samples, respectively), along with K, Ca, Mn, Ni and Cu, which are more abundant in the AHP samples. Furthermore, the Principal Component Analysis (PCA) was applied to the experimental dataset in order to classify and discriminate the samples, in relation to their similar botanical origin, but different for the color of the bloom. These results can be useful for the traceability of raw materials potentially intended for the production of auxiliary systems of pharmacological interest.

Wine identification is one of the most important aspects in the classification of wines and consumer protection. In particular, assuring wine authenticity is a crucial issue on which researchers are focusing on. This study aims to evaluate the feasibility of using chemical (B, Pb and Sr concentration) and isotopic compositions (δ11B, 20yPb/20xPb, 87Sr/86Sr and δ18O) of wine samples to trace their geographic origins. Different PDO Lambrusco wines coming from a confined area of northern Italy were analyzed and all the isotopic systematics were monitored by using a multi collector inductively coupled plasma mass spectrometer (MC-ICP/MS). The obtained results showed that boron isotope ratio measurements led to a satisfactory degree of accuracy and precision (measured value, n = 28, 11B/10B of NIST SRM 951a equal to 4.04343 ± 0.00178, (u = 2s) with a certified value of 4.04362 ± 0.00136 (u = 2s). Furthermore, in the present study, it has been possible to highlight significant differences among samples by means of one-way analysis of variance (ANOVA) and post hoc Tukey-Kramer test. Finally, Principal Component Analysis (PCA) was also carried out in order to evaluate to which extent the different PDOs can be distinguished from each other, taking into account the whole set of geographical origin descriptors. Although δ11B provided more sensitive information, the obtained results highlighted the important to consider the synergistic combination of all the investigated parameters to trace the different samples and the need to combine the obtained values with the same parameters evaluated in the soil, water and fertilizer as well., Graphical abstract Image 1, Highlights • Multi-parameter approach was used to assess wine geographical origin. • Validation of 11B/10B measurements was accomplished by multicollector ICP/MS. • 11B/10B, 87Sr/86Sr, 20yPb/20xPb, 18O/16O, and relative elemental content, were measured in Lambrusco PDO wines. • Anova, Tukey-Kramer and multivariate (PCA) analysis was employed to investigate differences and similarities among samples. • Geographic differentiation of PDO wines resulted to be based more on B and Sr variables than Pb and O ones.

In this study, the lead isotope signature was tested with the aim to verify its potential as geographic tracer for wine production and particularly for the Lambrusco PDO wines of the province of Modena (Italy). A solid phase extraction procedure, for separating lead from the investigated matrices, soil and wine, was optimized. Furthermore, different mathematical models, based on an exponential law and internal or external correction approach, were evaluated for the correction of instrumental mass dependent fractionation. The optimized analytical procedure yielded isotopic ratio data relative to the lead NIST 981 standard, 208Pb/206Pb = 2.16664 and 207Pb/206Pb = 0.914645, in good agreement both with the tabulated values and with the most recent literature data. Measured isotope ratio data highlight the contribute of multiple lead sources in bottled wine but different from the one present in soils.

This study summarizes the results obtained from a systematic and long-term project aimed at the development of tools to assess the provenance of food in the oenological sector. In particular, 87Sr/86Sr isotope ratios were measured on statistically representative set of soils, vine branches and wines sampled in the production district of Modena, worldwide known for the Lambrusco wines production. The obtained data were used to build strontium isotopic maps able to objectively support the Lambrusco PDO wines origin as well as other products of the Modena district. Finally, a strong relationship was found between the 87Sr/86Sr isotope ratios of soils and vine branches on a large scale, highlighting and confirming once more the idea that plants can also represent an optimal sampling device to support geographical traceability.

Microwave-assisted extraction was applied to Juglans regia L. fresh male flowers and unripe walnut seeds to evaluate the total phenolic contents of the extracts as well as the percentage of water-soluble polyphenols. The research was planned using the Design of Experiments technique to investigate the role on the extraction efficiency of different parameters, such as temperature, time and number of microwave heating cycles, together with their possible interactions. Optimization was achieved by applying a Response Surface Methodology comprising a three-factor, two-level, full-factorial Face-Centred Central Composite Design. The two input variables with a significant effect on the recovery of phenols from fresh male flowers were the extraction temperature and the number of microwave cycles. In the case of unripe walnut seeds, a linear two-factor interaction model was selected, with significant interactions occurring between temperature and time, and time and number of microwave cycles. The best experimental conditions were as follows: 100 °C, 6 min, three microwave heating cycles and 22.7 ± 0.2 mg gallic acid equivalent (GAE)/g (total phenolic content, PC); energy consumption calculations suggested slightly different conditions: 60 °C, 30 min, three microwave heating cycles and 20.7 ± 0.3 mg GAE/g (TPC).

This study summarizes the results obtained from a systematic and long-term project aimed at the development of tools to assess the provenance of food in the oenological sector. In particular

The content of total hexavalent chromium (CrVI), total chromium (Cr) and other metals (Fe, Mn, Ni and Co) was determined in the cement matrix of concrete present in samples collected in both old and recent buildings located in the town of Modena (northern Italy). The cement matrix of concrete was obtained by eliminating the aggregate components by means of disaggregation and was ground until it could pass through a 63-μm-sieve. In addition, samples of bagged commercial cements were considered. Metal determination was obtained by inductively coupled plasma optical emission spectroscopy after strong acid dissolution (HCl–HNO3). Total Cr(VI) determination was obtained after mild acid attack (HCl) and analysed by UV–Vis spectrophotometry. Analytical data values obtained indicate that the highest concentrations of metals were found in concrete and in bagged cement samples characterized by high Fe concentration. High Cr(VI) concentrations both in the cement matrix of concrete and in cement samples were found in total Cr-rich samples. Cr(VI) concentrations were about 20–30% of total Cr. The data obtained indicate that secondary raw materials and industrial by-product powders utilized in the modern cement industry may significantly increase Cr(VI) in concrete.

In the Italian oenological industry, the regular practice used to naturally increase the colour of red wines consists in blending them with a wine very rich in anthocyanins, namely Rossissimo. In the Asian market, on the other hand, anthocyanins extracted by black rice are frequently used as correctors for wine colour. This practice does not produce negative effects on health; however, in many countries, it is considered as a food adulteration. The present study is therefore aimed to discriminate wines containing anthocyanins originated from black rice and grapevine by using reliable spectroscopic techniques requiring minimum sample preparation. Two series of samples have been prepared from five original wines, that were added with different amounts of Rossissimo or of black rice anthocyanins solution, until the desired Colour Index was reached. The samples have been analysed by FT-NIR and (1)H NMR spectroscopies and the resulting spectra matrices were subjected to multivariate classification. Initially, PLS-DA was used as classification method, then also variable selection/classification methods were applied, i.e. iPLS-DA and WILMA-D. The classification with variable selection of NIR spectra permitted to classify the test set samples with an efficiency of about 70%. Probably these not excellent performances are due to the matrix effect, together with the lack of sensitivity of NIR with respect to minor compounds. On the contrary, very satisfactory results were obtained on NMR spectra in the aromatic region between 6.5 and 9.5 ppm. The classification method based on wavelet-based variables selection, permitted to reach an efficiency in validation greater than 95%. Finally, 2D correlation analysis was applied to FT-NIR and (1)H NMR matrices, in order to recognise the spectral zones bringing the same chemical information.

This study summarizes the results obtained from a systematic and long-term project aimed at the development of tools to assess the provenance of food in the oenological sector. 87Sr/86Sr isotope ratios were measured on a representative set of soils, branches, and wines sampled from the Chianti Classico wine production area. In particular, owing to the high spatial resolution of the 87Sr/86Sr ratio in the topsoil, the effect of two mill techniques for soil pretreatment was investigated to verify the influence of the particle dimension on the measured isotopic ratios. Samples with particle sizes ranging from 250 to less than 50 &micro, m were investigated, and the extraction was performed by means of the DIN 19730 procedure. For each sample, the Sr isotope ratio was determined as well. The obtained results showed that the 87Sr/86Sr ratio is not influenced by soil particle size and may represent an effective tool as a geographic provenance indicator for the investigated product.

A selection of samples, obtained from a particular copper-alloy domestic artefact of Roman style from Pompeii, has been analysed by using different techniques (IR, Raman, SEM-EDX, FAAS), in order to investigate the chemical nature and composition of the metals utilised for such manufacturing pieces. The surface analysis of the bright red metallic microfragments conducted by different analytical techniques, emphasises the presence of pure unalloyed copper and confirms the absence of other metallic species on the upper layers. On the contrary, the mapping analysis of the section of the laminar metal of the investigated sample shows a consistent enrichment in tin content. Finally, destructive analysis by FAAS confirms that the artefact looks like a bronze metal alloy, with a medium Sn content of about 6.5%.

Different kinds of bread, stored at constant temperature and at controlled humidity conditions for a week since their manufacturing date, were analysed by Attenuated Total Reflectance-Fourier Transform InfraRed (ATR-FTIR) spectroscopy. The collected spectra were processed by Principal Component Analysis (PCA), in order to evaluate the changes occurring during bread ageing. For the sake of comparison, the 1060-950 cm−1-1 spectral window has been also investigated by curve-fitting methods. It was observed that the first PC increases monotonically with ageing of samples. Furthermore, the more influential variables on PC1 correspond to spectral regions where are located stretching and bending bands, which are mainly attributed to typical starch bonds vibrations.

Kinematic viscosities were measured for 2-butanone + 2-butanol binary liquid mixtures with a capillary Ubbelohde routine viscometer in the temperature range from 273.15 to 353.15 K at atmospheric pressure, and covering the whole miscibility field (0⩽x i ⩽1). Experimental data have been correlated by means of different empirical or semiempirical relationships, such as ν=ν(T), ν=ν(x i ), and ν=ν(T, x i ). Viscosity deviations, Δν, from ideal behavior are negative at all experimental conditions, confirming that structure breaking effects prevail in the liquids. Furthermore, the thermodynamics of viscous flow and excess Gibbs energy of activation of viscous flow, G* E , have been calculated. As an alternative and complementary approach to such investigations, the fluidity (ϕ) of this binary system has been analyzed by the modified—Batschinski theory. The results are discussed in terms of the specific molecular interactions between the mixture components.

The static dielectric constant (e) of ethane-1,2-diol+1,2-dimethoxyethane + water ternary mixtures was measured as a function of temperature (263.15 ≤ T (K) ≤ 353.15) and composition, over the complete mole fraction range 0 ≤ x 1, x 2, x 3≤ 1. The experimental values were analyzed by empirical relationships that accounted for the dependence e = e(T) and Y = Y(x i). A comparison between calculated and experimental data shows that these fitting relationships can be reliably used to predict e values, along with other related properties, in areas of experimental data gaps. Starting from the experimental measurements, some derived quantities such as molar orientational polarization (P), dipolar interaction free energy ( F μ) and the relevant thermodynamic excess mixing properties (F μ E, F―E μ,i), were obtained. The values of the excess quantities are indicative of the presence of specific interactions between different components in the mixtures. A discussion of data in terms of the Kirkwood theory also provides information on the short-range intermolecular interactions, suggesting the formation of stable two-:component adducts rather than of more complex moieties involving all three molecular species.

The density of the 2-chloroethanol (CE) + 2-methoxyethanol (ME) + 1,2-dimethoxye- thane (DME) ternary mixtures has been measured at different temperatures ranging from −10 to 80°C, and over the entire composition range. The experimental data have been used to check the validity of some relationships accounting for the dependence of the density on temperature and composition domains. Starting from the primary data, some derived quantities, such as excess molar volumes VE, partial molar volumes \(\bar V_{\text{i}} \) and partial excess molar volumes \(\bar V_{\text{i}}^E \), have been obtained. In these mixtures, VE is always positive for the [CE(1) + ME(2)] binaries, while it is generally negative at all other experimental conditions, showing the greatest deviations along the binary axes corresponding to the binary subsystems in the sequence [CE(1) + DME(2)] < [CE(1) + ME(2)] < [ME(1) + DME(2)]. The results are compared and discussed to in terms of changes in molecular association and structural effects in these solvent systems.

Density of the 1,2-dichloroethane + 2-methoxyethanol or 1,2-dimethoxyethane binary mixtures have been measured at different temperatures over the complete composition range. Several experimental measurements have been used to check the validity of the relationships accounting for the dependence of the density on temperature and composition, useful to obtain interpolated values in correspondence of the experimental data gaps. Starting from the primary data, some derived quantities, such as partial molar volumes, excess and partial excess molar volumes, have been obtained. In these mixtures, V E is always positive for DCE + ME binaries, while an S-shaped dependence on composition at each temperature is obtained in DCE + DME system, showing positive values in the DCE rich-region and negative values at the opposite extreme. The results are compared and discussed to shed some light to the changes in molecular association and structural effects in these binary solvent systems.

The kinematic viscosity ν for (ethane-1,2-diol + 1,2-dimethoxyethane + water) was measured at 14 different ternary compositions covering the whole miscibility field, and at 19 temperatures in the range 263.15 ⩽T / K ⩽ 353.15. The experimental values were fitted using empirical equations of the type ν = ν ( T ) and ν = ν ( x i ), respectively, in order to provide reliable models to account for the behaviour of the system. The excess kinematic viscosity ν E has been determined and interpreted in terms of the type and nature of the interactions among the components of the mixture. Using the experimental ν data, the thermodynamic properties ( ΔG * , ΔH * , ΔS * ) of the viscous flow have been obtained from the Eyring’s approach and standard thermodynamic equations. Furthermore, excess mixing functions, such as ΔG * E , have been determined, and found to evidence the existence of quite strong specific interactions among the components, probably due to the formation of hydrogen bonds and dipolar networks. However, all the calculated excess mixing properties suggest the absence of stable three-component adducts.

Density refractive index n and the related properties molar volume V and molar refraction R have been investigated for 2-butanone + n-hexane liquid binary mixtures over the entire composition range and a wide range of temperatures. Some well-known relationships have been applied to study the temperature and composition dependence of the measured and derived quantities. Furthermore, the deviations of the respective excess properties VE, nE, and RE have been examined, with the aim of identifying particular intermolecular interaction patterns responsible for the macroscopic behavior of these binary mixtures. The results have been interpreted on the basis of structural and geometric effects between the components.

Kinematic viscosities of the binary 2-butanone (1) + 1,2-propanediol (2) solvent system have been measured for mixtures covering the whole miscibility range expressed by 0 ≤ xi ≤ 1, at 19 temperatures in the range −10 ≤ t/°C ≤ 80. The measured values have been used to test empirical equations that express the kinematic viscosities as functions of the composition and temperature. Excess kinematic viscosities (νE) have also been calculated. Sign and magnitude of these quantities are discussed in terms of type and nature of specific intermolecular interactions. Furthermore, derived quantities such as thermodynamic parameters of viscous flow (ΔG‡, ΔH‡ and ΔS‡), are analyzed on the basis of Eyring's model. All the investigated excess mixing properties indicate the probable existence of stable two-component adducts in this binary solvent system.

Static relative permittivities of the 2-methoxyethanol + 1,2-dimethoxyethane + water ternary solvent system were measured as a function of temperature (−10 ≤ t/°C ≤ 80) and of composition, over the whole molar fractions range 0 ≤ x2, x2, x3 ≤ 1. The experimental values have been used to test some empirical relationships accounting for the dependence of e on T, xi, and on T, xi couples of values. A comparison between calculated and experimental data shows that these relationships can be profitably employed to predict e values in correspondence to experimental data gaps. The excess dielectric permittivity, eE, assumes, in the most cases, negative values for any compositions of the mixtures, while the values of the excess molar polarization, PE, are positive. The large values of the excess quantities are indicative of the strong specific interactions among similar, as well as different molecules in the mixtures. Discussion of the data in terms of Kirkwood correlation factor also gives information on the short-range intermolecular interactions among the components, suggesting the formation of two-components adducts rather than of than more complex moieties involving all three molecular species.

Thermodynamic interactions in the ethane-1,2-diol (1) + 1,2-dimethoxyethane(2) + water (3) ternary system have been investigated in terms of the excessmolar volume, derived from density measurements at 19 different temperaturesfrom −10;dg to 80;dgC. Fourteen three-component mixtures have been considered,covering the entire composition range. The excess molar volumes are discussedin terms of conformational changes induced in each component by the presenceof another one. The results obtained support the hypothesis of the absence of anythree-component complex adducts under all experimental conditions investigated.

Kinematic viscosities (ν) of the ternary ethane-1,2-diol (1)+2-methoxyethanol (2)+water (3) solvent system have been measured for 36 ternary mixtures covering the whole miscibility range expressed by the condition 0

On a determine 1' indice de refraction de melanges liquides binaires 2-methoxyethanol (ME) + 1,2-dimethoxyethane (DME) a 15 temperatures allant de 0 a 70°C, utilisant les deux solvants purs et 9 melanges qui couvrent tout le domaine de miscibilite (0 ≤ X i ≤ 1). Dans le but d' evaluer leur validite dans le cas present, on a applique quelques equations empiriques et semi-empiriques pour etablir la dependance fonctionnelle de n, de la temperature et de la composition, en considerant soit 1' echelle des fractions molaires soit 1' echelle des fractions volumiques. En outre, on a calcule les valeurs de les quantites n E et R E (refraction molaire d' exces), qui se referent a la deviation de l'idealite des proprietes refractives des melanges binaires par rapport aux valeurs decoulant de la loi de Raoult. On a attribue les valeurs n E et R E a l'existence d' une interaction specifique, entre les molecules dissemblables, conduisant a la formation de deux differents complexes entre le ME et le DME, a l' etat liquide, avec les rapports stoechiometriques ME: DME = 1:1 et 2:1, qui paraissent thermostables a toutes les temperatures etudiees.

Densities ρ are reported for {ethane-1,2-diol (1) + 2-methoxyethanol (2) + water (3)} at 19 temperatures ranging from T =(263.15 to 353.15) K on 36 ternaries of different mole fractions covering the whole miscibility field 0 x 1 / x 2 / x 3 The experimental data have been used to test some empirical equations expressing the functions ρ=ρ( T ) and ρ=ρ( x 1 , x 2 , x 3 ), and the excess molar volumes V E have been derived and used to investigate the presence of three component stable adducts in these mixtures.

The densities (ρ) and excess molar volumes (VE) for 1,2-dimethoxyethane + water binary mixtures were determined, when possible, at 19 different temperatures ranging from −10 up to +80 °C. The experimental measurements were used to test some empirical relations giving the dependence of the density on the temperature and binary composition: ρ = ρ(t), ρ = ρ(X1), and ρ = ρ(t,X1). Furthermore, the results of VE calculations are discussed in terms of the influence of interactions between the components, of the order and degree of packing in the mixtures, and of the free-volume differences.

Static dielectric constants (e) were measured for mixtures of 1,2-dichloroethane (DCE, 1) + 2-methoxyethanol (ME, 2) + 1,2-dimethoxyethane (DME, 3) at 19 temperatures in the range −10 ≤ t/°C ≤ 80, employing 12 ternaries covering the whole composition range expressed by the mole fractions 0 X 1 , X 2 , X 3 e = e ( T ), e = e ( X i ) and e = e ( T , X i ), which might be useful for correlation and interpolation procedures, were used to represent the experimental data. The excess mixing property e E has been evaluated to investigate the presence of solvent-cosolvent adducts at each temperature. The quantity e E has been found to be partly positive and partly negative in the ternary domain { X 1 , X 2 , X 3 }. As a consequence, it is possible to observe an isoline at e E = 0 at each temperature. Such a line represents a large set of ternary mixtures having a pseudo-ideal dielectric behavior, even being formed by interacting components.

Static dielectric constants (e) were determined for the 1,2-dichloroethane (DCE, 1)/2-chloroethanol (CE, 2) binary solvent system at 19 temperatures ranging from −10 to +80 °C and in the whole composition range expressed by the mole fraction 0 ≤ X1 ≤ 1. The experimental values have been fitted to some equations that could be usefully employed for predictive e calculations. Furthermore, the excess mixing properties (eE) have been evaluated in order to point out the presence of solvent–cosolvent adducts in the binary mixtures mentioned above. The values of eE have been generally found to be negative and only slightly positive under a few experimental conditions in the CE rich-region, thus giving evidence of a close interaction network probably via hydrogen bonding as well as other interactions of every kind in this solvent system.

Dynamic viscosity (η) of binary solvent mixtures of N,N-dimethylformamide (DMF, component 1) + 2-methoxyethanol (ME, component 2) has been investigated at 19 temperatures ranging from −10 to +80 °C. Some empirical equations have been applied in order to establish the best regression fitting procedures η = η(T), η = η(X1) and η = η(T, X1). For this binary solvent system, the viscometric properties are continuous but not linear functions of the mixture composition. Therefore, experimental η values were used to calculate the excess viscosities (ηE) and excess Gibbs activation energies (ΔG*E) of viscous flow. Both these quantities strongly deviate from ideality over the whole composition range of the investigated mixtures. Furthermore, deviations from the ideal behaviour could be very useful in order to evidentiate the formation of solvent–cosolvent complex species and to evaluate their stoichiometrical composition.