A high sensitivity system for luminescence measurement of materials.

A unique combined and multi-disciplinary wavelength multiplexed spectrometer is described. It is furnished with high-sensitivity imaging plate detectors, the power to which can be gated to provide time-resolved data. The system is capable of collecting spectrally resolved luminescence data following X-ray excitation [radioluminescence (RL) or X-ray excited optical luminescence (XEOL)], electron irradiation [cathodoluminescence (CL)] and visible light from light emitting diodes (LEDs) [photoluminescence (PL)]. Time-resolved PL and CL data can be collected to provide lifetime estimates with half-lives from microsecond timeframes. There are temperature stages for the high and low temperature experiments providing temperature control from 20 to 673 K. Combining irradiation, time resolved (TR) and TR-PL allows spectrally-resolved thermoluminescence (TL) and optically stimulated luminescence (OSL). The design of two detectors with matched gratings gives optimum sensitivity for the system. Examples which show the advantages and multi-use of the spectrometer are listed. Potential future experiments involving lifetime analysis as a function of irradiation, dose and temperature plus pump-probe experiments are discussed.

Effects of Tm3+ concentration on upconversion luminescence and temperature-sensing behavior in Tm3+/Yb3+:Y2O3 nanocrystals.

The effects of Tm3+ concentration on upconversion emission and temperature-sensing behavior of Tm3+/Yb3+:Y2O3 nanocrystals were investigated. Blue and red emissions were observed under 980 nm excitation. Both upconversion emissions and the blue to red intensity ratio were found to decrease with increasing Tm3+ concentration. The temperature-sensing performances of the samples were studied, the fluorescence intensity ratio of 1G4(a)→3H6 (477 nm) and 1G4(b)→3H6 (490 nm) transitions from Tm3+ ions was chosen as the thermometric index. The results showed that the sensor sensitivity was sensitive to Tm3+ ion concentration. The maximum sensitivity of ~32 × 10-4 K-1 was obtained for 0.1%Tm3+/5%Yb3+:Y2O3 nanocrystals at 344 K. Moreover, a marked optical induced heating effect was also found in the nanocrystals. The prepared Tm3+/Yb3+:Y2O3 nanocrystals could be used in temperature-sensing probes and in optical heaters.

Rare Earth Element Labeling as a Tool for Assuring the Origin of Eggs and Poultry Products.

Laying hens were fed terbium and thulium supplemented feed in order to introduce a distinctive rare earth element pattern that allows discrimination of labeled from unlabeled poultry products. Samples of egg yolk, egg shells, meat, bones, liver, blood, and feces were analyzed using either conventional or laser ablation inductively coupled plasma mass spectrometry. Already after a short time of administering supplemented feed, terbium and thulium enrichment could be unambiguously detected in the products, while absolute terbium and thulium contents remained low enough to ensure safety for the customer. This method could potentially be applied to specifically label foodstuffs produced in certain regions or under certain conditions, in order to ensure food authenticity.

Luminescence analysis of SrGa2 Si2 O8 : RE3+ (RE = Dy, Tm) phosphors.

This article reports on the luminescence properties of rare earth (Dy3+ and Tm3+ )ions doped SrGa2 Si2 O8 phosphor were studied. SrGa2 Si2 O8 phosphors weresynthesizedby employing solid state reaction method.From the measured X-ray diffraction (XRD) pattern of the samplemonoclinic phase structure has been observed. Thermoluminescenceand Mechanoluminescence properties of the γ-ray irradiated samples have been studied. Photoluminescence spectra of Dy3+ activated SrGa2 Si2 O8 phosphor has been measured with an excitation wavelength at 348 nm,and it shows two emission bands at 483 and 574 nm due to 4 F9/2  â†’ 6 H15/2 and 4 F9/2  â†’ 6 H13/2 transitions respectively. Whereas the photoluminescence spectra of Tm3+ activated SrGa2 Si2 O8 phosphor has been measured with an excitation wavelength at 359 nm and it exhibits two emission bands at 454 and 472 nm due to 1 D2  â†’ 3 F4 and1 G4  â†’ 3 H6 transitions respectively. In thermoluminescence study, γ-irradiatedthermoluminescence glow curve of SrGa2 Si2 O8 :Dy3+ phosphor shows two well defined peaks at 293 °C (peak1)and 170 °C (peak2) whereas thermoluminescence glow curve of SrGa2 Si2 O8 :Tm3+ phosphor shows peaks at 292 °C (peak1) and 184 °C (peak2) indicating that two sets of traps are being activated within the particular temperature range and the trapping parameters associated with the prominent glow peaks of SrGa2 Si2 O8 :Dy3+ and SrGa2 Si2 O8 :Tm3+ are calculated using Chen's peak shape and initial rise method.From the Mechanoluminescence study, only one glow peak has been observed. Copyright © 2016 John Wiley & Sons, Ltd.

Elemental bioimaging of thulium in mouse tissues by laser ablation-ICPMS as a complementary method to heteronuclear proton magnetic resonance imaging for cell tracking experiments.

Due to the fact that cellular therapies are increasingly finding application in clinical trials and promise success by treatment of fatal diseases, monitoring strategies to investigate the delivery of the therapeutic cells to the target organs are getting more and more into the focus of modern in vivo imaging methods. In order to monitor the distribution of the respective cells, they can be labeled with lanthanide complexes such as thulium-1,4,7,10-tetraazacyclodoecane-α,α,α,α-tetramethyl-1,4,7,10-tetraacetic acid (Tm(DOTMA)). In this study, experiments on a mouse model with two different cell types, namely, tumor cells and macrophages labeled with Tm(DOTMA), were performed. The systemic distribution of Tm(DOTMA) of both cell types was investigated by means of laser ablation-inductively coupled plasma-mass spectrometry (LA-ICPMS). Using the high resolution of 25 µm, distribution maps of Tm in different tissues such as tumor, liver, lung, and spleen as well as in explanted gel pellets were generated and the behavior of the labeled cells inside the tissue was investigated. Additionally, quantitative data were obtained using homemade matrix-matched standards based on egg yolk. Using this approach, limits of detection and quantification of 2.2 and 7.4 ng·g(-1), respectively, and an excellent linearity over the concentration range from 0.01 to 46 µg·g(-1) was achieved. The highest concentration of the label agent, 32.4 µg·g(-1), in tumor tissue was observed in the area of the injection of the labeled tumor cells. Regarding the second experiment with macrophages for cell tracking, Tm was detected in the explanted biogell pellet with relatively low concentrations below 60 ng·g(-1) and in the liver with a relatively high concentration of 10 µg·g(-1). Besides thulium, aluminum was detected with equal distribution behavior in the tumor section due to a contamination resulting from the labeling procedure, which includes the usage of an Al electrode.

Modeling a hypothetical 170Tm source for brachytherapy applications.

PURPOSE: To perform absorbed dose calculations based on Monte Carlo simulations for a hypothetical (170)Tm source and to investigate the influence of encapsulating material on the energy spectrum of the emitted electrons and photons. METHODS: GEANT4 Monte Carlo code version 9.2 patch 2 was used to simulate the decay process of (170)Tm and to calculate the absorbed dose distribution using the GEANT4 Penelope physics models. A hypothetical (170)Tm source based on the Flexisource brachytherapy design with the active core set as a pure thulium cylinder (length 3.5 mm and diameter 0.6 mm) and different cylindrical source encapsulations (length 5 mm and thickness 0.125 mm) constructed of titanium, stainless-steel, gold, or platinum were simulated. The radial dose function for the line source approximation was calculated following the TG-43U1 formalism for the stainless-steel encapsulation. RESULTS: For the titanium and stainless-steel encapsulation, 94% of the total bremsstrahlung is produced inside the core, 4.8 and 5.5% in titanium and stainless-steel capsules, respectively, and less than 1% in water. For the gold capsule, 85% is produced inside the core, 14.2% inside the gold capsule, and a negligible amount (<1%) in water. Platinum encapsulation resulted in bremsstrahlung effects similar to those with the gold encapsulation. The range of the beta particles decreases by 1.1 mm with the stainless-steel encapsulation compared to the bare source but the tissue will still receive dose from the beta particles several millimeters from the source capsule. The gold and platinum capsules not only absorb most of the electrons but also attenuate low energy photons. The mean energy of the photons escaping the core and the stainless-steel capsule is 113 keV while for the gold and platinum the mean energy is 160 keV and 165 keV, respectively. CONCLUSIONS: A (170)Tm source is primarily a bremsstrahlung source, with the majority of bremsstrahlung photons being generated in the source core and experiencing little attenuation in the source encapsulation. Electrons are efficiently absorbed by the gold and platinum encapsulations. However, for the stainless-steel capsule (or other lower Z encapsulations) electrons will escape. The dose from these electrons is dominant over the photon dose in the first few millimeter but is not taken into account by current standard treatment planning systems. The total energy spectrum of photons emerging from the source depends on the encapsulation composition and results in mean photon energies well above 100 keV. This is higher than the main gamma-ray energy peak at 84 keV. Based on our results, the use of (170)Tm as a brachytherapy source presents notable challenges.

Bioimaging and toxicity assessments of near-infrared upconversion luminescent NaYF4:Yb,Tm nanocrystals.

In vitro or in vivo bioimaging utilizing the upconversion (UC) luminescence of rare earth fluoride nanocrystals (NCs) has attracted much attention, especially for Yb(3+)/Tm(3+) doped NCs with a near-infrared (NIR) UC emission at 800 nm. Herein, water-soluble NaYF(4):Yb,Tm NCs with strong NIR UC emission were synthesized with a solvothermal method. In vitro and in vivo bioimaging and toxicity assessments were carried out with HeLa cell and Caenorhabditis elegans (C. elegans) cases, respectively. NaYF(4):Yb,Tm NCs afforded an efficient NIR image of the HeLa cells with an incubation concentration of 10 µg mL(-1), and CCK-8 assay revealed a low cytotoxicity. Fed with Escherichia coli (E. coli) and NCs together, the C. elegans showed a NIR image in the gut from the pharynx to the anus. Further, these NCs could be excreted out when those worms were then fed with only E. coli. Toxicity studies were further addressed with protein expression, life span, egg production, egg viability, and growth rate of the worms in comparison with those of the intact ones. The feeding of rare earth fluoride NCs with a dose of 100 µg does not arise obvious toxicity effect from the growth to procreation. The in vitro and in vivo studies confirm that NaYF(4):Yb,Tm NCs could be served as an excellent NIR emission bioprobe with low toxicity.

The thermoluminescence efficiency of Li2B4O7:Cu and of CaSO4:Tm for photons.

The intrinsic thermoluminescence (TL) efficiency of a TL detector relates the absorbed dose in the detector material to the light yield observed upon evaluation. Knowledge of the TL efficiency is of interest when performing numerical simulations of detector response, where only absorbed dose can be predicted. Here, the experimental determination of TL efficiency for calcium sulphate (CaSO(4):Tm) and lithium borate (Li(2)B(4)O(7):Cu) is reported. These materials are widely used in Panasonic dosemeter badges. The results of the study are in agreement with predictions from track structure theory and microdosimetry, relating an enhanced light yield at low X-ray energies to supralinear behaviour of the TL phosphor.

Brain temperature and pH measured by (1)H chemical shift imaging of a thulium agent.

Temperature and pH are two of the most important physiological parameters and are believed to be tightly regulated because they are intricately related to energy metabolism in living organisms. Temperature and/or pH data in mammalian brain are scarce, however, mainly because of lack of precise and non-invasive methods. At 11.7 T, we demonstrate that a thulium-based macrocyclic complex infused through the bloodstream can be used to obtain temperature and pH maps of rat brain in vivo by (1)H chemical shift imaging (CSI) of the sensor itself in conjunction with a multi-parametric model that depends on several proton resonances of the sensor. Accuracies of temperature and pH determination with the thulium sensor - which has a predominantly extracellular presence - depend on stable signals during the course of the CSI experiment as well as redundancy for temperature and pH sensitivities contained within the observed signals. The thulium-based method compared well with other methods for temperature ((1)H MRS of N-acetylaspartate and water; copper-constantan thermocouple wire) and pH ((31)P MRS of inorganic phosphate and phosphocreatine) assessment, as established by in vitro and in vivo studies. In vitro studies in phantoms with two compartments of different pH value observed under different ambient temperature conditions generated precise temperature and pH distribution maps. In vivo studies in alpha-chloralose-anesthetized and renal-ligated rats revealed temperature (33-34 degrees C) and pH (7.3-7.4) distributions in the cerebral cortex that are in agreement with observations by other methods. These results show that the thulium sensor can be used to measure temperature and pH distributions in rat brain in vivo simultaneously and accurately using Biosensor Imaging of Redundant Deviation in Shifts (BIRDS).

[Spectral interferences of rare earth elements observed with a high resolution inductively coupled plasma atomic emission spectrometer. V. Spectral interferences of lutetium, thulium, yttrium and ytterbium as matrices].

The spectral interferences of Lu, Tm, Y and Yb (100 microns.mL-1, separately) as matrices on the other REEs (1 or 5 microns.mL-1) were observed with a high resolution ICP-AES with a grating of 3,600 grooves.mm-1. Totally 66 analytical lines of 15 REEs were selected as the prominent lines for spectral interference studies. The "Q" values and "the true detection limit" were calculated for the selected prominent lines with the exist of the four matrix elements. The obtained information is useful in the selection of the best analytical lines for the determination of REEs in the other REEs' matrices.

Ion microscopy, a method for imaging the distribution of trace elements in the lung.

Analytical ion microscopy, a method of surface microanalysis, is applied to the detection of trace elements in the lung. With this method it is possible to obtain images of the distribution of any element in lung tissue sections with a resolution of 0.5 micron and with very high sensitivity (of an order of magnitude 3 or 4 times greater than with X-ray microanalysis). Under these conditions it is possible to study at the microscopic level the penetration into the lung cells of mineral materials administered in physiological amounts. The images are formed by ion microscopy of atoms sputtered as charged particles from the specimen, and these atoms are selected by mass spectrometry. This technique has been applied to the detection of aerosols (diam. less than 1 micron) of rare earths (thulium or cerium chloride), inhaled in very small amounts (20-50 micrograms), in cells from the lung of a rat. Images of the distribution of these elements were obtained in a few seconds or minutes, when X-ray microanalysis gave either a weak signal or none at all. Their behaviour in the lung could be easily studied several weeks after the end of the inhalation.