@article{WunderKutzschbachHosseetal.2018, author = {Wunder, Bernd and Kutzschbach, Martin and Hosse, Luisa and Wilke, Franziska Daniela Helena and Schertl, Hans-Peter and Chopin, Christian}, title = {Synthetic B-[4]-bearing dumortierite and natural B-[4]-free magnesiodumortierite from the Dora-Maira Massif}, series = {European journal of mineralogy}, volume = {30}, journal = {European journal of mineralogy}, number = {3}, publisher = {Schweizerbart}, address = {Stuttgart}, issn = {0935-1221}, doi = {10.1127/ejm/2018/0030-2742}, pages = {471 -- 483}, year = {2018}, abstract = {Dumortierite was synthesized in piston-cylinder experiments at 2.5-4.0 GPa, 650-700 degrees C in the Al2O3 -B2O3-SiO2-H2O (ABSH) system. Electron-microprobe (EMP) analyses reveal significant boron-excess (up to 0.26 B-[4] per formula unit, pfu) and silicon-deficiency relative to the ideal anhydrous dumortierite stoichiometry Al7BSi3O18 . The EMP data in conjunction with results from single-crystal Raman spectroscopy and powder X-ray diffraction provide evidence that silicon at the tetrahedral site is replaced by excess boron via the substitution Si-[4] <--> B-[4] + H. The Raman spectrum of synthetic dumortierite in the frequency region 2000 4000 cm(-1) comprises eight bands, of which six are located at frequencies below 3400 cm(-1). This points to strong hydrogen bonding, most likely O2-H center dot center dot center dot O7 and O7-H center dot center dot center dot O2, arising from a high number of octahedral vacancies at the All site and substitution of trivalent Al3+ and B3+ for Si4+ at Si1 and Si2 sites, causing decreasing acceptor-donor distances and lower incident valence at the acceptor oxygen. Contrary to the synthetic high-pressure ABSH-dumortierite, magnesiodumortierite from the Dora-Maira Massif, which is assumed to have formed at similar conditions (2.5-3.0 GPa, 700 degrees C), does not show any B-excess. Tourmaline shows an analogous behaviour in that magnesium-rich (e.g., dravitic) tourmaline formed at high pressure shows no or only minor amounts of tetrahedral boron, whereas natural aluminum-rich tourmaline and synthetic olenitic tourmaline formed at high pressures can incorporate significant amounts of tetrahedral boron. Two mechanisms might account for this discrepancy: (i) Structural avoidance of Mg-[6]-(OR3+)-R-[4] configurations in magnesiodumortierite due to charge deficieny at the oxygens O2 and O7 and strong local distortion of M1 due to decreased O2-O7 bond length, and/or (ii) decreasing fluid mobility of boron in Al-rich systems at high pressures.}, language = {en} } @article{SchmaelzlinMoralejoGersondeetal.2018, author = {Schm{\"a}lzlin, Elmar Gerd and Moralejo, Benito and Gersonde, Ingo and Schleusener, Johannes and Darvin, Maxim E. and Thiede, Gisela and Roth, Martin M.}, title = {Nonscanning large-area Raman imaging for ex vivo/in vivo skin cancer discrimination}, series = {Journal of biomedical optics}, volume = {23}, journal = {Journal of biomedical optics}, number = {10}, publisher = {SPIE}, address = {Bellingham}, issn = {1083-3668}, doi = {10.1117/1.JBO.23.10.105001}, pages = {11}, year = {2018}, abstract = {Imaging Raman spectroscopy can be used to identify cancerous tissue. Traditionally, a step-by-step scanning of the sample is applied to generate a Raman image, which, however, is too slow for routine examination of patients. By transferring the technique of integral field spectroscopy (IFS) from astronomy to Raman imaging, it becomes possible to record entire Raman images quickly within a single exposure, without the need for a tedious scanning procedure. An IFS-based Raman imaging setup is presented, which is capable of measuring skin ex vivo or in vivo. It is demonstrated how Raman images of healthy and cancerous skin biopsies were recorded and analyzed. (C) The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License.}, language = {en} }