Electrochemical monitoring of the storage or stabilization of archaeological copper based artefacts in sodium sesquicarbonate solutions

Archaeological copper-based artifacts recovered from wet and salty environments are often stored or stabilized in sodium sesquicarbonate solutions. Modification of the natural patina and development of active corrosion can occur during these processes, which implies the need for monitoring storage/stabilization processes. The focus of the study consists of examining how corrosion potential (Ecorr) measurements and voltammetric curves can contribute in providing information on the effectiveness of storage and stabilization treatments. Particular attention is given to side effects such as the transformation of the corrosion layers

Electrochemistry reveals archaeological materials

The characterization of materials constituting cultural artefacts is a challenging step in their conservation, due to the object’s uniqueness and the reduced number of conservation institutes able to supply non-destructive analysis. We propose an alternative analytical tool, which combines accessibility (low cost and portable) and high sensitivity, based on electrochemical linear sweep voltammetry (LSV) with paraffin impregnated graphite electrode (PIGE). To investigate the composition of “white alloys” that certainly have been used as decoration on copper-based Roman fibulae, sampling was done very locally by gently rubbing the selected areas with the PIGE. LSV results evidence the presence of silver, lead, and tin, supporting the argument provided by typological analysis that these metals were used for decoration

Test-retest reliability of questionnaires regarding attitudes and beliefs toward noise, hearing loss and hearing protector devices in young adults

Context: Young people expose themselves to high noise levels during leisure activities, and might thus be at risk of acquiring hearing-related problems. Therefore, information regarding risk-taking behavior is necessary to prevent future hearing problems and to optimize future preventive campaigns. Aim: This study evaluated the test–retest reliability of the Youth Attitude to Noise Scale (YANS) and beliefs about hearing protection and hearing loss (BAHPHL) instrument. Settings and Design: Forty-three young adults between 18 and 29 years filled in a questionnaire at two test moments. Materials and Methods: The YANS and BAHPHL instrument were used to evaluate the attitudes toward noise, hearing loss, and hearing protection. Each participant completed the retest within 21–55 days after the first administration of the questionnaire. Results: Paired Student’s t-tests showed no significant differences in mean scores between test and retest for both the entire YANS and BAHPHL instrument as well as their factors. Furthermore, a good agreement between test and retest scores was seen by Bland–Altman analyses. Intraclass correlation coefficients were above 0.70 for the entire YANS and the factor related to youth culture as well as for the entire BAHPHL and all the factors of the BAHPHL instrument, except for the factor related to the severity of the consequences of hearing loss. Conclusion: Reliable test–retest measurements of the YANS and BAHPHL instrument can be performed. Hence, these questionnaires can be used in longitudinal studies to explore young adults’ changes in attitudes toward noise, hearing loss, and hearing protection, with or without an educational intervention

Study of Corrosion Potential Measurements as a Means to Monitor the Storage and Stabalization Processes of archaeological Copper Artefacts

Archaeological copper artefacts recovered from wet saline environments are often stored in tap water and stabilized in sodium sesquicarbonate solutions. Modification of the natural patina and development of active corrosion can occur during these processes. This implies that monitoring of storage/stabilisation processes is necessary. The focus of the study consists of examining how corrosion potential (Ecorr) measurements can contribute in providing information on the effectiveness of storage and stabilisation treatments. This paper reports on the Ecorr versus time plots of artificially prepared copper coupons (covered or not with corrosion layers) immersed in tap water and a sodium sesquicarbonate solution. Synchrotron radiation XRD was performed in parallel to understand the reactions that take place during the immersion processes

Unraveling the effects of co-crystallization on the UV/Vis absorption spectra of an N-salicylideneaniline derivative:A computational RI-CC2 investigation

This work aims at unraveling the effects of co-crystallization on the optical properties of an N-salicylideneaniline-derived molecular switch transforming between an enol and a keto form. This is achieved by way of a two-step multi-scale method where (i) the molecular geometry and unit cell parameters are optimized using a periodic boundary conditions density functional theory method and (ii) the optical properties are computed for a selection of clusters embedded in an array of point-charges that reproduce the crystal field electronic potential. The optical properties (vertical excitation energies and oscillator strengths) are obtained at the RI-CC2/def2-TZVPD level of approximation. This method allows us to decompose the effects of co-crystallization into (i) indirect effects, the geometry changes of the chromophore due to crystal packing with the coformer, and (ii) direct ones, the polarization due to the interacting coformer and to the crystal field. For the former effects, variations of a crucial torsion angle lead to modification of the p-conjugation and therefore to the decrease or increase of the excitation energies. About the latter, they are antagonistic: (i) the coformer is not directly involved in the excitations but its polarization decreases the excitation energies while (ii) the crystal field has the opposite effect. For the co-crystals with succinic and fumaric acids, combining these direct and indirect effects leads to a hypsochromic shift of the first absorption band with respect to the reference crystal, in agreement with experimental data