Comparison of on-wafer calibrations using the concept of reference impedance

A novel method that allows to compare different calibration techniques has been developed. It is based on determining the reference impedance of a given Network Analyzer calibration from the reflection coefficient measurement of a physical open circuit. The method has been applied to several on-wafer calibrations.Peer ReviewedPostprint (published version

Tracing the tin-opacified yellow glazed ceramics in the western Islamic world: the findings at Madinat al-Zahra’

A small group of opaque yellow glazed sherds has recently been identified among the ceramics excavated at the Islamic city of Madinat al-Zahra’ near Cordoba, in al-Andalus (southern Spain), which was founded in 936 AD as the seat of the Umayyad Caliphate power. A small group of sherds from Madinat al-Zahra’, which can be dated to about 960–980 AD, has been examined in polished section in a SEM with EDS attached. These analyses have established that the Madinat al-Zahra’ sherds were opacified with lead stannate, and not lead antimonate, as was being used to opacify yellow glazed ceramics in Egypt and Tunisia in the ninth and tenth centuries AD. Islamic opaque yellow glazed ceramics, with lead stannate as the opacifier, were first produced (Beiträge Zur Islamischen Kunst Und Archäologie 4:125–144, 2014) in Egypt and Syria in seventh/eighth centuries AD, and from there, the technology spread eastwards into Iraq and Iran in the ninth century AD and continued in use in Iran and Central Asia into the tenth century AD and beyond. However, the question of where these opaque yellow glazed ceramics were produced has not been fully resolved. Because such ceramics are extremely rare in al-Andalus, it seems most likely that they were either imported from Iran or Central Asia or produced locally by potters arriving from these areas. The study adds one further, yet not fully understood chapter to the story of a persistent glaze technology which has been widely ignored.Peer ReviewedPostprint (published version

The Sexual Objectification Experiences of Non-Binary People

Transgender people are a historically marginalized and disenfranchised group, leading to discriminatory interpersonal treatment such as sexual objectification experiences (SOEs), a type of objectification. Women look at themselves the way men look at them, reducing themselves to objects for someone else’s viewing. This flattening of oneself to value your bodily presentation over functioning increases dissociative states and promotes disordered eating behaviors. Non-binary people experience additive stressors within objectification experiences as people with less social power than cisgender women. This thesis is composed of three separate studies aimed at understanding the SOEs of non-binary people. The first of three studies recruited 10 non-binary people to explore their SOEs through interviews. Non-binary participants shared sexual objectification experiences, the impact SOEs had on their wellbeing, and the resilience they cultivated in the face of SOEs. The second study used a flow chart tool to process SOEs in a sample of 10 non-binary people, instructing participants to use the chart in real time to move through a SOE. Participants described an emotionally rich experience with this tool and generally found it helpful as well as challenging. Finally, the third study used body maps, or the artistic expression of participants’ relationships with their bodies, to further explore the impact that SOEs had on the participants’ relationship with their bodies with 10 non-binary participants. It is our hope that findings from these thesis studies will be used for increased awareness and advocacy on the experiences of non-binary people in clinical practice and research

The ways of the lustre: looking for the tunisian connection

Recent excavations at the Fatimid and Zirid site of Sabra al-Mansuriya near Kairouan (Tunisia) provide the first evidence of lustreware production in medieval Ifriqiya, in the 10th–11th centuries AD. As the Fatimid dynasty moved from Ifriqiya to Egypt to establish its capital in Fustat (Cairo), technological connections with the Egyptian lustreware could be expected. Tunisian lustreware may also be the link in the transmission of the technique towards Muslim Spain. It represents a new piece of the puzzle of understanding the diffusion of lustre technology from the East to the West of the Mediterranean. The composition and microstructure of the bodies and glazes, and the micro- and nano-structure of the lustre layer are compared in a preliminary approach to the technological relationships between Tunisian, Egyptian, and Spanish lustrewares.Peer ReviewedPostprint (published version

Ageing of resin from Pinus species assessed by infrared spectroscopy

Resins obtained from Pinus genus species have been widely used in very different fields throughout history. As soon as the resins are secreted, molecular changes start altering their chemical, mechanical and optical properties. The ageing processes are complex, and the chemical and structural changes associated with resin degradation are not yet fully known. Many questions still remain open, for instance changes happening in pimaranes, one of the two diterpenoid constituents of the resin. A systematic study of the ageing process of Pinus resins is done through Fourier transform infrared spectroscopy (FTIR) using chemical standards and complementing the obtained results with gas chromatography coupled to mass spectrometry (GC/MS) analysis when necessary. Moreover, long-term degradation processes are also investigated through the analysis of a selection of dated historical resins. This study overcomes the limitations of GC/MS and brings new information about the reactions and interactions between molecules during Pinus resin ageing processes. It also provides information about which bonds are affected and unaffected, and these can be used as specific markers of the degradation and of the resins themselves. [Figure not available: see fulltext.]Peer ReviewedPostprint (author's final draft

Ceramic technology. How to characterise ceramic glazes

Glazes add value to ceramic, improve its appearance (colour and shine) and make it waterproof. Through the choice of colours and designs, glazes made ceramics fashionable, even luxurious, and therefore, an object of trade. Each region and ruling dynasty developed its own style or trademark which makes them particularly suitable for dating purposes. Therefore, the study and analysis of glazes offers direct information about the acquisition of technical skills (technology), trade of specific materials (interregional links), migrations and the introduction/adoption of new trends. A ceramic glaze is a thin glassy layer fused to the surface of a ceramic body through firing. The interaction between the glaze and the ceramic body results in the interdiffusion of elements between both. A glaze consists mainly of an amorphous phase, but also includes bubbles, cracks and crystalline phases (undissolved compounds and crystals formed during the firing). Finally, the glazes were also decorated, and a large variety of materials and methods of applying the decorations were used. In this chapter, we present a summary of the technical characteristics of glazes (composition, microstructures and technical requirements), their discovery and use throughout history and decorative techniques. The methodology and analytical techniques to obtain the information are also discussed.Peer ReviewedPostprint (author's final draft

Thermal properties and stability of Catalan Modernist blue and green enamels

Stained glass is a fragile component of our Cultural Heritage. In particular, the stained glass produced during the last decades of the 19th century and first decades of the 20th century is characterised by the use of a new type ready-to-use enamels. Stained glass was used for the windows of buildings, and a large part of it is exposed to weathering and consequently to deterioration. This study analyses the collection of materials used in one of the most important stained glass Modernist workshops in Barcelona. The chemical composition is determined (and pigments identified) by means of Laser Ablation Inductively-Coupled Plasma Mass Spectrometry (LA-ICP-MS) and X-Ray Diffraction (XRD) and the thermal properties of the enamels measured by Differential Scanning Calorimetry (DSC) and Hot Stage Microscopy (HSM). The enamels are made of a lead-zinc borosilicate glass characterised by its low sintering temperatures and high stability against chemical corrosion, in particular to water corrosion. However, the relatively narrow range of firing temperatures necessary for correct adherence of the enamels to the contemporary glass base may have required the addition of a high lead borosilicate flux, which would have increased the lead content of the enamel, decreasing the firing temperature but also its stability

La Química de l'art

Els materials que formen part d'una obra d'art, per les seves característiques de disponibilitat, disposició i concentració requereixen per a la seva anàlisi unes metodologies de mostreig i de preparació adaptades, així com la utilització de tècniques microanalítiques. Dels resultats es pot obtenir informació molt diversa i útil per al millor coneixement i conservació de les obres. Es mostren alguns exemples on les eines químiques aplicades al coneixement de l'art permeten conèixer les tecnologies de producció i origen dels materials, relacionar-los amb manuscrits i receptes antigues, interpretar fenòmens d'alteració, estudiar la reactivitat i els productes de reacció així com determinar cronologies.Els materials que formen part d?una obra d?art, per les seves característiques de disponibilitat, disposició i concentració requereixen per a la seva anàlisi unes metodologies de mostreig i de preparació adaptades, així com la utilització de tècniques microanalítiques. Dels resultats es pot obtenir informació molt diversa i útil per al millor coneixement i conservació de les obres. Es mostren alguns exemples on les eines químiques aplicades al coneixement de l?art permeten conèixer les tecnologies de producció i origen dels materials, relacionar-los amb manuscrits i receptes antigues, interpretar fenòmens d?alteració, estudiar la reactivitat i els productes de reacció així com determinar cronologies. The chemical analysis of materials in works of art requires special techniques both in the sampling process as well in the preparation of probes. In this field, the use of microanalytical techniques is essential. Interestingly, a great wealth of information can be obtained from chemical analysis, that provides a better knowledge of the artwork as well as on the conservation techniques. In this article we review some examples where the application of chemical characterization techniques applied to works of art have been important in obtaining a precise knowledge on the production techniques of the materials as well as on their origin, relating them to manuscripts describing old recipes. These techniques allow us also to interpret the phenomena that change a work of art along the time, to study the chemical reactivity of the materials and their reaction products, a knowledge that can be used to establish a chronology of the artwork

The transition from lead transparent to tin-opacified glaze productions in the western Islamic lands: al-Andalus, c. 875 – 929 CE

The earliest glazed ware in al-Andalus is dated to the Emiral period (c. 850 – 875 CE) and is not until the Caliphate of Córdoba (929 –1031 CE) that a distinctive polychrome tin glaze started being produced. A short transition period (c. 875 – 925 CE) in which elaborate monochrome and bichrome transparent glazes wares co- exist with polychrome transparent and tin opaque glazed wares has been identi fied. The existence of a poly- chrome lead transparent glaze production in al-Andalus wares is demonstrated; it has distinctive composition and methods of production from monochrome and bichrome wares, and shares a distinctive absence of foot and overglaze application of the decorations with the tin-opacified wares. With regard to the possible routes of the introduction of the polychrome lead and tin glazes into the western Mediterranean the Tunisian connection seems completely discarded. Moreover, and although some similarities between the Cordoba and the Abbasid productions such as similar tin glaze recipe and decorative patterns and use of lead glazes, can be traced, the dissimilarities, such as, the use of overglaze decorations, absence of alkali transparent glazes, variances in the tableware shapes and absence of foot, are still more important, and do not support a clear link between them.Peer ReviewedPostprint (author's final draft