Reproduction of melting behavior for vitrified hillforts based on amphibolite, granite, and basalt lithologies

European Bronze and Iron Age vitrified hillforts have been known since the 1700s, but archaeological interpretations regarding their function and use are still debated. We carried out a series of experiments to constrain conditions that led to the vitrification of the inner wall rocks in the hillfort at Broborg, Sweden. Potential source rocks were collected locally and heat treated in the laboratory, varying maximum temperature, cooling rate, and starting particle size. Crystalline and amorphous phases were quantified using X-ray diffraction both in situ, during heating and cooling, and ex situ, after heating and quenching. Textures, phases, and glass compositions obtained were compared with those for rock samples from the vitrified part of the wall, as well as with equilibrium crystallization calculations. ‘Dark glass’ and its associated minerals formed from amphibolite or dolerite rocks melted at 1000–1200 °C under reducing atmosphere then slow cooled. ‘Clear glass’ formed from non-equilibrium partial melting of feldspar in granitoid rocks. This study aids archaeological forensic investigation of vitrified hillforts and interpretation of source rock material by mapping mineralogical changes and glass production under various heating conditions.

Obsidian and Obsidian-like Glass Tesserae: A Multidisciplinary Approach to Study the Dedication Wall Mosaic in the Church of St. Mary of the Admiral in Palermo (12th Century)

Pliny the Elder testifies that roman workshops used volcanic glass (obsidian), but also produced and used a dark glass (obsidian-like glass) quite similar to the natural one. In the context of the study on medieval mosaics, the use of the obsidian and obsidian-like tesserae is a challenging research topic. In this paper, we present the results of a multidisciplinary study carried out on the Dedication wall mosaic, realized by a byzantine workshop in the 12th century in the Church of St. Mary of the Admiral in Palermo, and where numerous black-appearing tesserae, supposed to be composed of obsidian by naked-eyes observation, are present. Historical documents, multispectral imaging of the wall mosaic, and some analytical methods (SEM-EDS and XRPD) applied to a sample of black tesserae, concur in identifying here the presence of obsidian and different obsidian-like glass tesserae. This evidence, although related to the apparent tampering and restoration, could open a new scenario in the use of obsidian and obsidian-like glass tesserae during the Byzantine period in Sicily and in the reconstruction of multiple restoration phases carried out between 12th and 20th century AD on the mosaics of St. Mary of the Admiral.

Afterword: Theatre and Speculation

The face-to-face encounter is a figure for direct, immediate contact between two entities. It has a long history, from Paul’s assertion that what he sees now in a glass darkly he will some day meet face to face to Emmanuel Levinas’ attempt to refound philosophy as based on its confrontation with another. But in seeking to determine the conditions under which the face to face could take place—absolute transparency to the absolutely other—its writers have risked stripping it of the contingencies and particularities that actually mark face-to-face encounters in the world. They have accidentally rendered it as theory and as theophany. Theatrical performance shows another view of the face to face, restoring to it the confusions and quirks of the world, embracing the dark glass of Paul’s wordly speculation rather than the promise of a more perfect vision always still to come. By executing the clarities that are hoped for in the face-to-face encounter, theater shows its shortcomings and discovers in them unhoped for points of contact.

Mass Spectroscopic Evaluation of Virgin Olive Oils (VOOs) Fatty Acid Profile in terms of Cultivar, Geographical Origin, Extraction and Packaging Type

Ensuring the olive oil quality and authenticity has become a great importance for both traditional and emerging olive oil producing countries. The chemical composition in olive oil heavily varies depending on the olive cultivar and its growing region, the agronomic applications, the olive oil production methods and the process and storage conditions. With the help of some analytical techniques and data evaluation methods, it is possible to grade olive oils in terms of their differences. This research examines particularly fatty acid composition of commercial olive oils (2017/2018 season) with mass detector coupled with gas chromatography (GC/MS). Results were evaluated for grading of them according to IOC regulations based on cultivar (ripe or unripe Ayvalik and Memecik), production (organic, stone mill, cold press, two or more centrifugation systems, filtered or unfiltered) and packing type (transparent or dark glass bottle and plastic bottle), and also their geographic origin (Ayvalik and Edremit towns, the Cunda Island, North Aegean region or South Aegean Region). According to overall data processing, virgin olive samples could be successfully distinguished in terms of theirs geographic origin and cultivar roots. Moreover, it was also explained that the effect of process and package type for grading of olive oils as ‘extra virgin’ or ‘virgin’.

Pengaruh Penambahan Ekstrak Bahan Alami Terhadap Laju Oksidasi Minyak Kelapa

THE INFLUENCE OF NATURAL EXTRACT TO THE COCONUT OIL OXIDATION RATE. Indonesia's coconut plantation is the largest in the world, with a share of 31.2% of the total coconut plantation area in the world. One of the products from coconut is coconut oil. However, coconut oil has a short storage time. Therefore, this experiment aims to estimate and optimize the storage time of coconut oil. The coconut oil used as the experimental sample was an oil made by traditional method. The coconut oils tested in this experiment included coconut oil, plus carrots, pineapple extracts of 10 and 30% -v/v, 10 and 30% -v/v young papaya, and 10 and 30% -v/v tomatoes. The mixture of coconut oil and carrot pieces was stored in light and dark glass bottles, while the mixture of coconut oil and liquid extract was stored only in dark glass bottles. The estimation method of storage time was based on literature values of acid number and peroxide number approximated by equation regression method and Artificial Neural Network (ANN). The experimental results showed that the storage time of coconut oil was 37-41 days for blank oil (in light and dark glass bottles), 50-51 days for the addition of carrot cuts in bright glass bottles, 56-57 days for the addition of carrot carrot cuts in glass bottles dark, 41-45 days for addition of pineapple liquid extract 10% -v/v, 30-32 days for 30% -v/v, 63-64 days for the addition of young papaya 10% -v/v, 55-62 days for 30% -v/v, 24-27 days for tomato liquid extract 10% -v/v, and 17-21 days for 30% -v/v. Keywords: natural antioxidant; artificial neural network; acid number; peroxide number; coconut oil; storage time Abstrak Perkebunan kelapa Indonesia merupakan terbesar di dunia, dengan pangsa 31,2% dari total areal perkebunan kelapa di dunia. Salah satu produk dari kelapa adalah minyak kelapa. Minyak kelapa memiliki umur simpan yang singkat. Penelitian ini bertujuan untuk memperkirakan dan mengoptimasi umur simpan minyak kelapa. Minyak kelapa yang dijadikan sampel eksperimen merupakan minyak yang dibuat berdasarkan metode tradisional. Minyak kelapa yang diuji pada eksperimen ini meliputi minyak kelapa blanko, ditambah potongan wortel, ekstrak cair nanas 10 dan 30 %-v/v, pepaya muda 10 dan 30%-v/v, serta tomat 10 dan 30 %-v/v. Minyak kelapa blanko dan yang ditambah potongan wortel disimpan dalam botol kaca terang dan gelap, sedangkan minyak kelapa yang ditambah ekstrak cair hanya disimpan dalam botol kaca gelap. Metoda perkiraan umur simpan dilakukan berdasarkan nilai-nilai pustaka (literature value) bilangan asam dan bilangan peroksida yang didekati dengan metoda regresi persamaan dan Artificial Neural Network (ANN). Hasil eksperimen menunujukkan bahwa umur simpan minyak kelapa adalah 37-41 hari untuk minyak blanko (dalam botol kaca terang dan gelap), 50-51 hari untuk penambahan potongan wortel dalam botol kaca terang, 56-57 hari untuk penambahan potongan wortel wortel dalam botol kaca gelap, 41-45 hari untuk penambahan ekstrak cair nanas 10%-v/v, 30-32 hari untuk 30%-v/v, 63-64 hari untuk penambahan pepaya muda 10%-v/v, 55-62 hari untuk 30%-v/v, 24-27 hari untuk ekstrak cair tomat 10%-v/v, serta 17-21 hari untuk 30%-v/v. Kata kunci: antioksidan alami; artificial neural network; bilangan asam; bilangan peroksida; minyak kelapa; umur simpan