Forensic analysis of inks by imaging desorption electrospray ionization (DESI) mass spectrometry

Desorption electrospray ionization mass spectrometry (DESI-MS) is employed in the forensic analysis of documents. Blue ballpoint pen inks applied to ordinary writing paper are examined under ambient conditions without any prior sample preparation. When coupled to an automated moving stage, two-dimensional molecular images are generated. Proof-of-principle experiments include characterization of a simulated forged number and examination of older written records. This application of DESI has advantages over extractive techniques in terms of speed and sample preservation. The effects of the desorbing solvent composition, in this case a mixture of methanol and water, and of flow rate, are evaluated. Results suggest that the solubility of the analyte ( dyes Basic Blue 7, Basic Violet 3 and Solvent Blue 26) plays an important role in desorption from the paper surface.132546146

Reconceptualising PCK research in D&T education: proposing a methodological framework to investigate enacted practice

Since first conceived, the concept of pedagogical content knowledge (PCK) has attracted much attention. Despite being lauded by educationalists as the unique knowledge base of teachers, research on the concept over the past 30 years has yet to result in a universally accepted definition being presented. Much of the contentions surrounding the lack of an agreed upon conception appear to have stemmed from difficulties in understanding the relationship between PCK, other areas of teacher knowledge, teacher beliefs, and enacted practice. This paper considers the application of PCK frameworks to design and technology (D&T) education, through an analysis of the nature of the discipline from an ontological and epistemological perspective and contemporary perspectives on the construct of PCK. It is theorised that the volition afforded to teachers in D&T through weakly framed subject boundaries negates the effective application of PCK frameworks, as teachers’ beliefs have a greater impact on enacted practices. In an attempt to better understanding enacted practice in D&T education, the paper proposes a methodological framework centred on the interactions between teachers’ beliefs and knowledge in the discipline, through synthesising the concept of amplifiers and filters of practice with the nature of D&T education. The proposed framework outlines the need to recognise individual teachers’ conception of capability as a critical influence on enacted practice