Sensing soluble molecules through SERS substrates in one-step procedure: Unrevealing the Meiji woodblock printing materials.

Ultrasensitive SERS substrates allowed us to detect complex mixtures of coloring components from Meiji Japanese woodblock prints (1868-1912). In museum settings, compositional analyses have limitations due to restrictions to sampling advised by conservators and curators for the adequate preservation of the objects. An additional layer of complexity is brought by the high heterogeneity of heritage materials, usually not resolved with commercial portable instruments. High-performance instruments for in situ analyses are seldom available in museums. Furthermore, the chambers of most instruments for morphological or chemical characterization accommodate small samples rather than large or medium-sized objects. The innovative sampling strategy herein proposed comprises the gentle touch-dry removal of small coloring molecules weakly bound to the surface of heritage objects, transferred through a silicone sampler to planar SERS substrates with selected solvents in a one-step procedure. The analytical protocol reduces the amount of sample necessary for reliable identification of color components down to nanograms. The selectivity of the solvents combined with the geometry of the planar SERS sensing devices produces reliable signals for molecular identification, with no need for incision or wetting of the printed material. Further, 3D Raman imaging allowed us to reach an unprecedented degree of molecular discrimination, advancing previously available minimally-invasive instrumental methods used in heritage science research. The validation with historical inks from Meiji woodblock prints led to the identification of soluble synthetic azo ß-naphthols, barium sulfonic lakes, purple anilines, Prussian blue, glass arsenic sulfides and other traditional coloring media.

What Fate for Plastics in Artworks? An Overview of Their Identification and Degradative Behaviour.

This review is conceived as a guide for material science researchers and conservators aiming to face the problem of deterioration of contemporary artworks entirely or partially made of plastics. It initially illustrates the analytical approaches for identifying polymeric material components in 3D art objects, such as sculptures and installations, and provides a perspective of their limits and advantages. Subsequently, the methodologies used for studying the deterioration of contemporary art plastics are reviewed, emphasising the main effects of the different types of degradation (i.e., migration of additives, oxidation and hydrolysis) and suggesting the appropriate techniques for their detection. Finally, the application of artificial ageing tests is critically assessed. All the concepts are elaborated through case studies and examples.

Characterization of contemporary and historical acrylonitrile butadiene styrene (ABS)-based objects: Pilot study for handheld Raman analysis in collections.

Plastic materials are increasingly becoming part of private and public collections worldwide, either as design objects or artistic sculptures. The preservation of these highly degradable materials requires novel analytical approaches able to reveal their chemical composition to inform the tailoring of appropriate conservation procedures. In this work Raman spectroscopy and Surface-enhanced Raman Scattering (SERS) were proposed as methods for the characterization of ABS-based contemporary and historical LEGO® objects. Twenty-three objects of twelve different colors were analyzed by handheld and benchtop Raman instrumentation. In all cases clear identification of the constituent polymer matrices (ABS, polycarbonate, poly(methyl metacrylate)) was obtained. In addition, identification of major color components was achieved, such as copper phthalocyanines in green and blue objects. Low cost handheld instrumentation provided acceptable sensitivity towards polymers and coloring media, and was found suitable for initial screening of the objects. Benchtop Raman was used to confirm and further extend identification, as well as for building background information. Finally, SERS sensitivity was found comparable to the sensitivity achieved by benchtop Raman instrumentation. However, the associated minimally-invasive sampling method made SERS a valid alternative to direct Raman spectroscopy for the analysis of immovable and/or large-sized objects. Overall, this work represents the first systematic investigation on the potential of Raman and SERS spectroscopies as methods for minimal invasive and/or in situ analysis of historical and contemporary plastic objects.

Agrupación nutricional de las frutas y hortalizas en Venezuela / Nutritional grouping of fruits and vegetables in Venezuela

La falta de una clasificación única para las frutas y hortalizas (FyH) representa un reto al establecer recomendaciones o realizar evaluaciones de su consumo. Por ello, este estudio tiene como objetivo examinar la agrupación de las FyH en Venezuela, considerando únicamente su composición nutricional, en pro de ofrecer criterios científicos que puedan ayudar a establecer posteriormente una clasificación apropiada. Se trata de una investigación descriptiva y transversal que utilizó como fuente secundaria a los valores nutricionales presentados en la Tabla de Composición de Alimentos venezolana. Se compararon los aportes nutricionales de 73 frutas y 47 hortalizas, contra otros 27 alimentos de 8 grupos considerados como suplementarios. Se realizó una comparación entre los grupos de alimentos con la prueba ANOVA, una comparación entre las FyH a través de un análisis de componentes principales y se establecieron grupos de FyH a través del análisis por conglomerados. Se encontró que las FyH se distinguen significativamente de los otros grupos de alimentos, por su alto contenido de agua >80% y ácido ascórbico >35%, con un bajo aporte de proteínas <2% y grasas <1% (p<0,05). Se establecieron 5 grupos de FyH, de los cuales 2 distaron significativamente del promedio por su alto contenido de grasa, sodio o carbohidratos. Los hallazgos sugieren que el aporte nutricional pareciera no ser un factor concluyente para diferenciar entre las frutas y las hortalizas. En conclusión, establecer una clasificación definitiva de FyH considerando únicamente su aporte nutricional, sería limitado, ya que podrían ser muchos otros los factores intervinientes(AU)

The lack of a single classification for fruits and vegetables (F&V) represents a challenge when is necessary establishing recommendations or evaluating their consumption. This study aims to examine the grouping of F&V in Venezuela, considering only their nutritional composition, in order to offer scientific criteria that can help to establish an appropriate classification later. It is a descriptive and cross-sectional investigation that used as a secondary source the nutritional values presented in the Venezuelan Food Composition Table. The nutritional contributions of 73 fruits and 47 vegetables were compared against another 27 foods of 8 groups considered as supplementary. A comparison was made between the food groups with the ANOVA test, a comparison between the F&V through a principal component analysis and F&V groups were established through the cluster analysis. It was found that F&V are major distinguished from other food groups, due to their high-water content >80% and ascorbic acid >35%, with a low protein content <2% and fat <1% (p <0, 05). 5 F&V groups were established, of which 2 were significantly different from the average due to their high content of fat, sodium or carbohydrates. The findings suggest that the nutritional contribution appears not to be a conclusive factor to differentiate between fruits and vegetables. In conclusion, establishing a definitive classification of FyH considering only its nutritional contribution would be limited, since there could be many other factors involved(AU)

Detection of degradation markers from polymer surfaces by a novel SERS-based strategy.

This paper provides new insights for the study of polymer degradation through the detection of markers released at the polymer surface using Al-coated SERS active substrates. Combining a nanodestructive sampling procedure with the SERS sensitivity allows achieving detection limits much lower than traditional polymer characterization techniques, opening the way to the use of SERS as part of an innovative strategy to diagnose surface degradation in polymeric museum artefacts. The method was applied to artificially photo-aged model polymers and to museum artworks.