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Neu-Ulm, Germany

Mikhno A.O.,RAS Institute of Geology and Mineralogy | Schmidt U.,WITec GmbH | Korsakov A.V.,RAS Institute of Geology and Mineralogy
European Journal of Mineralogy

Confocal Raman Imaging revealed the coexistence of kokchetavite and K-cymrite (KAlSi3O8·H2O) in association with muscovite/phengite, lollingite, calcite and α-cristobalite in polyphase mineral inclusions in clinopyroxene of calc-silicate ultrahighpressure metamorphic (UHPM) rocks from the Kokchetav Complex (northern Kazakhstan). Experiments have shown that K-cymrite is stable under high pressure conditions; however, this phase never had been reported from UHPM rocks before. The mode of occurrence of K-cymrite and kokchetavite in these rocks is strong evidence for kokchetavite formation through the dehydration of K-cymrite. The presence of fluid inclusions and K-cymrite in the polyphase mineral inclusions testify for water-saturated conditions in the rock-forming environment near peak metamorphic conditions. © 2013 E. Schweizerbart'sche Verlagsbuchhandlung, D-70176 Stuttgart. Source

Rosner B.,Friedrich - Alexander - University, Erlangen - Nuremberg | Zeilmann N.,Friedrich - Alexander - University, Erlangen - Nuremberg | Schmidt U.,WITec GmbH | Fink R.H.,Friedrich - Alexander - University, Erlangen - Nuremberg
Organic Electronics: physics, materials, applications

Ultrathin pentacene films resemble benchmark and model materials for organic field-effect transistors (OFETs). We employ scanning transmission X-ray microspectroscopy (STXM) and confocal Raman microspectroscopy as highly resolving probes to obtain insight into the correlation of morphology and charge transport in pentacene OFETs. By combining the operation-induced intensity increase in Raman-active bands with micromorphology, we are able to visualize charge-induced effects, in particular charge trapping in pentacene OFETs during operation. The high sensitivity and specificity of Raman microscopy allows to distinguish between orientation and charge-induced effects and thus to locate the trapped charges at grain boundaries.© 2013 Elsevier B.V. All rights reserved. Source

Sahu A.,Chilakapati Laboratory | Sawant S.,Tata Memorial Center | Mamgain H.,WITec GmbH | Krishna C.M.,Chilakapati Laboratory

Early diagnosis of oral cancers, one of the major cancers, is of utmost importance as 5-year disease-free survival rates are some of the lowest, despite advances in treatment and surgical modalities. In vivo Raman spectroscopy has shown efficacy in the detection of normal, premalignant and malignant lesions and even of early changes such as cancer-field-effects/malignancy-associated- changes. However, the need for a dedicated instrument and stringent laboratory conditions, at all diagnostic centers, limits wide screening applications of this method. In light of this, it is pertinent to explore ex vivo samples like serum due to its ease of collection, storage, transport and analysis at a centralized facility. Hence, Raman studies were carried out on serum from 14 buccal mucosa and 40 tongue cancers as well as 16 healthy control samples. Spectral features indicate differential contributions of proteins, DNA, and amino acids like Phe, Trp and Tyr and p-carotene in the analyzed groups. Highly intense Raman bands assigned to p-carotene could be due to resonance Raman, and were observed in all sera with the highest relative intensity in normal samples. Higher DNA and protein content were observed in the mean cancer spectra. Principal component-linear discriminant analysis (PC-LDA) followed by cross-validation using leave-one-out cross-validation (LOOCV) were employed for data analysis which was carried out both spectra- and patient-wise. Findings indicate the possibility of classifying normal and oral cancer sera in both these approaches; however, the patient-wise approach could be the preferred mode for prospective studies. Besides, a tendency of classification for buccal mucosa and tongue cancers was also observed. Prospective validation of these results on a large sample size may help in the translation of this methodology to clinics. © The Royal Society of Chemistry 2013. Source

Millar R.W.,University of Glasgow | Gallacher K.,University of Glasgow | Samarelli A.,University of Glasgow | Frigerio J.,Polytechnic of Milan | And 4 more authors.
Optics Express

The room temperature photoluminescence from Ge nanopillars has been extended from 1.6 μm to above 2.25 μm wavelength through the application of tensile stress from silicon nitride stressors deposited by inductively-coupled-plasma plasma-enhanced chemical-vapour-deposition. Photoluminescence measurements demonstrate biaxial equivalent tensile strains of up to ∼1.35% in square topped nanopillars with side lengths of 200 nm. Biaxial equivalent strains of 0.9% are observed in 300 nm square top pillars, confirmed by confocal Raman spectroscopy. Finite element modelling demonstrates that an all-around stressor layer is preferable to a top only stressor, as it increases the hydrostatic component of the strain, leading to an increased shift in the band-edge and improved uniformity over top-surface only stressors layers. © 2015 Optical Society of America. Source

Buch Z.,Luminescent | Kumar V.,Luminescent | Mamgain H.,WITec GmbH | Chawla S.,Luminescent
Chemical Communications

Silver nanoprisms of different sizes influence fluorescence enhancement in YVO4:Eu3+ nanoparticles to various degrees under excitation of green light (532 nm). The local field generated by silver nanoprisms and their dimers is simulated through the FDTD method and a direct correlation with fluorescence enhancement is established. © 2013 The Royal Society of Chemistry. Source

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