Er3+-to-Yb3+ and Pr3+-to-Yb3+ energy transfer for highly efficient near-infrared cryogenic optical temperature sensing

Here, the very high thermal sensing capability of Er3+,Yb3+ doped LaF3 nanoparticles, where Er3+-to-Yb3+ energy transfer is used, is reported. Also Pr3+,Yb3+ doped LaF3 nanoparticles, with Pr3+-to-Yb3+ energy transfer, showed temperature sensing in the same temperature regime, but with lower performance. The investigated Er3+,Yb3+ doped LaF3 nanoparticles show a remarkably high relative sensitivity S-r of up to 6.6092% K-1 (at 15 K) in the near-infrared (NIR) region, in the cryogenic (15-105 K) temperature region opening a whole new thermometric system suitable for advanced applications in the very low temperature ranges. To date reports on NIR cryogenic sensors have been very scarce

TeSen : tool for determining thermometric parameters in ratiometric optical thermometry

This work presents the method and numerical program along with graphical user interface (GUI) for calculating the standard parameters necessary to evaluate luminescence ratiometric thermometers - the thermometric parameter Delta, absolute sensitivity S-a, and relative sensitivity S-r. Despite the high interest in temperature sensing materials, to the best of our knowledge, no such tool has been reported up to date. This is currently usually done by researchers using a trial and error method and is a rather laborious task, with high risk of errors. The undoubtful benefit of employing an optimization technique lies in the very fast and precise determination of the parameters employing different models. The thermometric parameters Delta, S-a and S-r are calculated based on the luminescence emission spectra measured over a certain temperature range. Using the TeSen tool the thermometric parameters Delta can be calculated based both on the peak maxima and integrated surface areas under the peaks. The tool also allows testing the ratio of multiple peaks, different peak ranges, and different temperature ranges in a very convenient way. In this work TeSen tool was used to study several new sensor materials, presenting new cases of single and dual center luminescent ratiometric theremometers

Optimal intermittent pneumatic compression in lymphedema

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Significance of Toll-like Receptors Expression in Tumor Growth and Spreading: A Short Review

Toll-like receptors (TLRs) are considered now as crucial sensors of innate immunity. Their role in the recognition of pathogens and the initiation of adaptive immune responses against them is well known. However, in last years TLRs have been identified on several tumor cells, including human malignancies. Their expression in cancer was found to be twofold: either promoting or inhibiting tumor progression. It was also demonstrated that several TLRs agonists, either natural or synthetic ones, may have beneficial effect on tumor-mediated disease, leading to potentiation of immune response to tumor-associated antigens. TLR-agonist linked tumor immunotherapy is still in nascent state, but growing rapidly, also in the area of common human malignancies. To date, the most promising and the most frequently studied interaction in tumor immunotherapy trials seems to be TLR9 and its synthetic agonists

Developing luminescent ratiometric thermometers based on a Covalent Organic Framework (COF)

Covalent Organic Frameworks (COFs), an emerging class of crystalline porous materials, are proposed as a new type of support for grafting lanthanide ions (Ln(3+)) and employing these hybrid materials as ratiometric luminescent thermometers. ATpBpy-COF-prepared from 1,3,5-triformyl-phloroglucinol (Tp) and 2,2'-bipyridine-5,5'-diamine (Bpy) grafted with Eu/Tb and Dy acetylacetone (acac) complexes can be successfully used as a luminescent thermometer in the 10-360 K (Eu) and 280-440 K (Tb) ranges with good sensing properties (thermal sensitivity up to 1.403% K-1, temperature uncertainty delta T < 1 K above 110 K). For the Eu/Tb systems, we observe an unusual and rarely reported behavior, that is, no thermal quenching of the Tb3+ emission, a result of the absence of ion-to-ligand/host energy back-transfer. The LnCOF materials proposed here could be a new class of materials employed for temperature-sensing applications following up on the well-known luminescent metal-organic framework thermometers

High temperature (nano)thermometers based on LiLuF4:Er3+,Yb3+nano- And microcrystals. Confounded results for core-shell nanocrystals

Recent technological developments require knowledge of temperature down to the micro- or even nano-scale. Lanthanide-doped nanoparticles became a popular tool to achieve this. Their temperature sensitive luminescence enables their application as remote thermometers and for mapping temperature profiles with high spatial resolution. Applicability of luminescence thermometry is, however, often limited at high temperatures. In nanoelectronics or chemical reactors, high temperatures above 500 K are common and new approaches for accurate high temperature sensing need to be developed. In this work, we report three different shapes of upconverting LiLuF4:2% Er3+,18% Yb3+nanocrystals both with and without shells and study the influence of the shell on the thermometric properties. We observed peculiar behavior of the core-shell particles suggesting the presence of the dopants within the protective and ‘undoped’ shells. Coating the nanoparticles with a silica layer extends the operational temperature range. In an upconversion (UC) Yb3+-Er3+system temperature sensing relies on thermal coupling between the4S3/2and2H11/2energy levels. At sufficiently high temperatures (>550 K), we observe additional thermal coupling involving the higher4F7/2energy levels. The larger energy gap allows to increase the relative sensitivity at elevated temperatures and to sustain a high temperature precision over a wider temperature range than for a two-level Boltzmann thermometer. The thermal coupling between the4S3/2and2H11/2energy levels is used for lower temperature sensing (550 K)