Lanthanide-based thermometers: At the cutting-edge of luminescence thermometry

Present technological demands in disparate areas, such as micro and nanofluidics, micro and nanoelectronics, photonics and biomedicine, among others, have reached to a development such that conventional contact thermal probes are not accomplished to perform accurate measurements with submicrometric spatial resolution. The development of novel non-contact thermal probes is, then, mandatory, contributing for an expansionary epoch of luminescence thermometry. Luminescence thermometry based on trivalent lanthanide ions becomes very popular since 2010 due to the unique versatility, stability and narrow emission band profiles of the ions that cover the entire electromagnetic spectrum with relatively high emission quantum yields. Here we give a perspective overview on the field since the beginnings in the 1950’s until the most recent cutting-edge examples. The current movement towards the technique usage as a new tool for thermal imaging, early tumor detection and as a tool for unveil properties of the thermometers themselves or of their local neighborhoods is also summarizedpublishe

Small RNA populations revealed by blocking rRNA fragments in Drosophila melanogaster reproductive tissues

RNA interference (RNAi) is a complex and highly conserved regulatory mechanism mediated via small RNAs (sRNAs). Recent technical advances in high throughput sequencing have enabled an increasingly detailed analysis of sRNA abundances and profiles in specific body parts and tissues. This enables investigations of the localized roles of microRNAs (miRNAs) and small interfering RNAs (siRNAs). However, variation in the proportions of non-coding RNAs in the samples being compared can hinder these analyses. Specific tissues may vary significantly in the proportions of fragments of longer non-coding RNAs (such as ribosomal RNA or transfer RNA) present, potentially reflecting tissue-specific differences in biological functions. For example, in Drosophila, some tissues contain a highly abundant 30nt rRNA fragment (the 2S rRNA) as well as abundant 5’ and 3’ terminal rRNA fragments. These can pose difficulties for the construction of sRNA libraries as they can swamp the sequencing space and obscure sRNA abundances. Here we addressed this problem and present a modified “rRNA blocking” protocol for the construction of high-definition (HD) adapter sRNA libraries, in D. melanogaster reproductive tissues. The results showed that 2S rRNAs targeted by blocking oligos were reduced from >80% to < 0.01% total reads. In addition, the use of multiple rRNA blocking oligos to bind the most abundant rRNA fragments allowed us to reveal the underlying sRNA populations at increased resolution. Side-by-side comparisons of sequencing libraries of blocked and non-blocked samples revealed that rRNA blocking did not change the miRNA populations present, but instead enhanced their abundances. We suggest that this rRNA blocking procedure offers the potential to improve the in-depth analysis of differentially expressed sRNAs within and across different tissues

Microcalorimetry of dust particles in a radio-frequency plasma

The internal temperature of rhodamine B-dyed dust particles (2rp = 1.2 µm) immersed in radio-frequency (rf) plasmas has been measured for various plasma conditions. For this purpose, the dye has been excited with an argon-ion laser and the fluorescent emission of the particles has been recorded with an optical multichannel analyzer system. The temperature has been determined after comparison with calibration curves. In argon, the particle temperature increases with rf power and is independent of pressure. In oxygen, an increase with rf power is observed, too. However, the energy flux towards the particles includes also heating by atom recombination (association) and exothermic combustion reactions. These temperature measurements have been compared with calculations based on the thermal balance, where measurements of gas temperature, electron density, and electron temperature have been used. A good agreement between theory and experiment has been found. ©2000 American Institute of Physics