Temperature Thermometry Research Articles

Microwave assisted preparation of ternary scheelite CaMoO4: Er3+/Yb3+ nano-phosphors for up/down-conversion photoluminescence, temperature sensing and antibacterial properties

Due to their exceptional intrinsic optical characteristics, molybdate compounds have aroused significant attention in recent years for their effective up and downconversion luminescence. In the present study, a series of xEr3+/Yb3+ (x = 0.5 %, 1 %, 2 %, 4 % and Yb3+ =15 %) doped CaMoO4 nanophosphors synthesized through a microwave assisted approach and subsequently the comprehensive analysis of the functionalities such as optical properties, antibacterial traits and their integration with temperature sensing, have been explored. Furthermore, the structural refinement confirms the occurrence of tetragonal scheelite phase of the prepared materials. The morphology of the material was identified by FE-SEM and HR-TEM analysis which reveals particles are in spherical shape. Up-conversion luminescence intensities were found to be dependent on doping concentration, laser excitation power and external temperature upon 980 nm light excitation. The temperature sensing response of the optimized sample was examined based on intensity ratio of two emission bands that involves thermally connected energy levels of Er3+ ion. The maximum absolute sensitivity of 10.74 × 10−3 K−1 (at 500 K) was found, demonstrating its potential application in high temperature thermometry. The comprehensive analysis and the outcome of the present study suggests the potential prospect of the as-synthesized material in food preservation, medical equipment, water treatment, and as an optical coating agent for solid state luminous devices.

Highly sensitive dual-mode temperature measurement utilizing completely opposite thermal quenching luminescence

In recent years, phosphors have been used in the field of temperature sensing, which has aroused great interest because of its advantages of quick response, high sensitivity and high accuracy. However, exploring optical thermometers with ultra-high sensitivity remains a challenge. In this work, we have designed and synthesized Sm3+ and Mn4+ co-doped La3Mg2NbO9 phosphor for temperature sensing for the first time by utilizing the anomalous thermal quenching property of Sm3+ ions and the sensitive thermal quenching property of Mn4+ ions. Furthermore, the structure, elemental distribution, morphology and optical characteristics of La3Mg2NbO9:Sm3+,Mn4+ were studied in detail. Benefiting from the different responses of the Sm3+ and Mn4+ ions to temperature, the fluorescence intensity ratios of Sm3+ to Mn4+ in La3Mg2NbO9 samples show excellent optical thermometry performance in the range of 303–463 K. The maximum absolute sensitivity (Sa) and relative sensitivity (Sr) values of La3Mg2NbO9:Sm3+,Mn4+ sample reach as high as 0.117 K-1 (@463 K) and 4.48 % K−1 (@303 K), respectively. Furthermore, the maximum of Sa is 0.385 K−1 (@463 K) and the maximum of Sr is 4.54 % K−1 (@303 K) based on the fluorescence lifetime temperature measurement method. The temperature cyclotron curve of the sample proves that the sample has excellent stability and repeatability in temperature measurement. These results demonstrate that the designed La3Mg2NbO9:Sm3+,Mn4+ phosphor is promising for the field of non-contact optical temperature thermometry.

A novel multifunctional Eu3+/Mn4+ co-doping double perovskite phosphor for applications in LEDs and optical thermometry

In recent years, phosphors have played important roles in solid-state lighting, plant growth lighting and optical temperature measurement. In this work, novel La3Mg2NbO9:Eu3+,Mn4+ phosphors were successfully prepared by the high temperature solid phase method and innovative multimode applications were investigated in optical thermometry, plant growth and White-LEDs. The crystal structure, surface morphology, photoluminescence, temperature sensing properties and luminescence mechanism of La3Mg2NbO9:Eu3+,Mn4+ phosphors were investigated in detail. Benefiting from the different responses of Eu3+ and Mn4+ ions to temperature, the La3Mg2NbO9:0.06Eu3+,0.0095Mn4+ sample shows excellent optical thermometry performance in the range of 303 ∼ 478 K. The maximum values of relative sensitivity (Sr) reach 2.7 % K-1 (@478 K) according to the fluorescence intensity ratio method and the maximum of Sr is 5.2 % K−1 (@428 K) based on the fluorescence lifetime method. Furthermore, the electrochromic spectrum of the red pc-LED prepared using La3Mg2NbO9:0.06Eu3+,0.005Mn4+ phosphor perfectly overlapped with the absorption bands of the photosensitive pigments for planting, and another white pc-LED prepared using La3Mg2NbO9:0.06Eu3+,0.0025Mn4+ phosphor emitted bright white light with a color rendering index of 89.8, color coordinate of (0.3468, 0.3557) and correlated color temperature of 4945 K. All the results demonstrate that the La3Mg2NbO9:Eu3+,Mn4+phosphors are promising for the field of non-contact optical temperature thermometry, plant lighting lamps and pc-LED backlit displays.

Near-infrared Cr3+-doped lead-free halide perovskite microcrystals for information encryption and temperature thermometry

Lead-free double perovskite materials have attracted lots of interest because they can be doped with luminescence activators to modify their optical characteristics and improve photoluminescence performances.

Electrodeposition of Platinum-Transition Metal Alloys for Magnetic Thermometry

The present work seeks to develop materials and structures with temperature-dependent magnetic properties providing optimal sensitivity for near-room temperature thermometry. Studies of the electrodeposition of Pt1-xMx (M=Ni,Co) alloys will be presented. The effects of boric acid and deposition potential on the deposition process and magnetic properties of Pt1-xNix and Pt1-xCox films will be compared. For Pt1-xNix, it was found that the presence of boric acid during deposition was accompanied by decreased Coulombic efficiency at more reducing deposition potentials, increased oxygen incorporation, and decreased magnetization relative to films deposited in the absence of boric acid.[1] Preliminary results for the Pt1-xCox system indicate its behavior is not simply analogous to the Pt1-xNix system.[1] Rus, E. D.; L. Corrêa, E.; Groopman, E.; Williamson, T.; Hijazi, H.; Kasaei, L.; Dennis, C. L.; Moffat, T. P., Magnetic Characterization of Electrodeposited Pt1−xNix Alloy Films: Influence of Deposition Potential and the Presence of Boric Acid, J. Electrochem. Soc. 2022, 169 (9), 10.1149/1945-7111/ac8ad1.

Magnetic resonance fingerprinting based thermometry (MRFT): application toex vivoimaging near DBS leads.

The purpose of this study is to demonstrate the first work ofT1-based magnetic resonance thermometry using magnetic resonance fingerprinting (dubbed MRFT). We compared temperature estimation of MRFT with proton resonance frequency shift (PRFS) thermometry onex vivobovine muscle. We demonstrated MRFT's feasibility in predicting temperature onex vivobovine muscles with deep brain stimulation (DBS) lead.B0maps generated from MRFT were compared with gold standardB0maps near the DBS lead. MRFT and PRFS estimated temperatures were compared in the presence of motion. All experiments were performed on a 3 Tesla whole-body GE Premier system with a 21-channel receive head coil (GE Healthcare, Milwaukee, WI). Four fluoroptic probes were used to measure the temperature at the center of a cold muscle (probe 1), the room temperature water bottle (probe 2), and the center and periphery of the heated muscle (probes 3 and 4). We selected regions of interest (ROIs) around the location of the probes and used simple linear regression to generate the temperature sensitivity calibration equations that convertT1maps and Δsmaps to temperature maps. We then repeated the same setup and compared MRFT and PRFS thermometry temperature estimation with gold standard probe measurements. For the MRFT experiment on DBS lead, we taped the probe to the tip of the DBS lead and used a turbo spin echo sequence to induce heating near the lead. We selected ROIs around the tip of the lead to compare MRFT temperature estimation with probe measurements and compared with PRFS temperature estimation. Vendor-suppliedB0mapping sequence was acquired to compare with MRFT-generatedB0maps. We found strong linear relationships (R2> 0.958) betweenT1and temperature and Δsand temperatures in our temperature sensitivity calibration experiment. MRFT and PRFS thermometry both accurately predict temperature (RMSE < 1.55 °C) compared to probe measurements. MRFT estimated temperature near DBS lead has a similar trend as the probe temperature. BothB0maps show inhomogeneities around the lead. MRFT estimated temperature is less sensitive to motion.

Chemostratigraphic contributions to paleoenvironmental assessment of microbialites from neoproterozoic Capiru Formation, Southern Ribeira Belt – Brazil

The Capiru Formation records supracrustal metassedimentary rocks within the Southern Ribeira Belt. These rocks underwent heterogeneous deformation and metamorphism, resulting in an incomplete greenschist facies paragenesis. They are tectonically interbedded with strata that exhibit well-preserved primary structures. In the Morro Grande synform region, there is a continuous 150 m outcrop of metadolomites with preserved sedimentary records and was described in a stratigraphic profile (1:500) subsequently detailed (1:50). Dolomite, minor amounts of quartz, traces of ilite, graphite and zircon constitute the mineral assembly, defined by XRD, petrography and SEM-EDS. Distinct preserved facies are recognized by morphostructures: (1) lamina (parallel, discontinuous, crenulated); (2) stromatolites (homogeneous columnar, club-shaped, conical conophyton-like, pseudocolumnar, parallel-branching, divergent-branching, delicate-branching); (3) thrombolite (rugous) and (4) flat pebble conglomerate. Single-isotope data revials different microbial patterns, particularly in stromatolites (−1.57 to −0.40‰ δ13C; −8.21 to - 3.94‰ δ18O) and lamina (−1.89 to 1.29‰ δ13C; −7.32 to −3.55‰ δ18O). Facies associations suggest a shallow sea with a regressive trend. Tectonofacies are characterized by massive, venulated or brecciated carbonates. Chemostratigraphic profile is divided into two major intervals. At the bottom, the first does not exhibit a specific isotopic trend and can be subdivided in heterogeneous post-deformation venulas (Unit I, −1.75 to 0.40 δ13C; −2.34 to −8.16 δ18O), thrombolythic signals (Unit II, −1.43 to 0.40‰ δ13C; −6.35 to −4.11‰ δ18O), and facies variation, mainly supratidal (Unit III, 1.89 to 1.29‰ δ13C, −7.32 to −3.31‰ δ18O). Upwads in the profile, the second interval consists of microbial facies, displaying a more uniform signature with depleted values of δ13C and δ18O along with a slight enrichment marking the transition from intratidal to supratidal environments (Unit IV; −1.32 to −0.81‰ δ13C; - 8.17 to −6.25‰ δ18O) and supratidal lagoons (Unit V; −1.35 to −0.41‰ δ13C; −8.20 to −5.49‰ δ18O). Preserved EPS, graphite, and ilite confirm low-grade metamorphism, with clumped isotope thermometry temperatures ranging from 206.07 to 307.58 °C. Calcite is secondary, filling porosity and present in recrystallized facies. Isotopic signature of recrystallized facies differs from microbial ones, with the most depleted values (−2.16‰ δ13C; −14.02‰ δ18O) and lower formation temperature (122.29 ± 7.07 °C), indicating a late restricted event. This dolomitic succestion within Capiru Formation provides evidence of a shallow marine paleoenvironment with diverse microbial activity during its deposition.

High sensitivity and multicolor tunable optical thermometry in Bi3+/Eu3+ co-doped Ca2Sb2O7 phosphors

Currently, with increasing demand for non-contact fluorescence intensity ratio-based optical thermometry, a novel phosphor with high-efficiency, dual-emitting centers, and differentiable temperature sensitivity is more and more urgent to develop. In this work, an efficient dual-emitting center optical thermometry with high sensitivity and multicolor tunable in Ca2Sb2O7:Bi3+, Eu3+ phosphor is firstly designed and successfully prepared. Under 330 nm excitation, the fabricated phosphor presents the featured and distinguishable emissions of Bi3+ and Eu3+ ions. The high efficiency energy transfer from Bi3+ to Eu3+ ions is proved and its corresponding mechanism belongs to dipole-dipole interaction. By modulating the ratio of Bi3+/Eu3+, the multicolor changes from blue to pink are realized. Based on the discriminative thermal quenching behavior between Bi3+ and Eu3+, the fluorescence intensity ratio of Eu3+ to Bi3+ in Ca2Sb2O7 samples illustrates excellent optical thermometry performance from 298 to 523 K. The maximum absolute sensitivity (Sa) and relative sensitivity (Sr) reach as high as 0.2773 K−1 at 523 K and 2.37% K−1 at 448 K, respectively. Notably, the discriminated surrounding temperature can be directly confirmed by observing the emitting color from purple to orange-red with the temperature increase from 298 to 523 K. Furthermore, the as-prepared phosphor materials also demonstrate outstanding repeatability and excellent reversibility. These results exhibit that the designed Ca2Sb2O7:Bi3+, Eu3+ phosphors have great promising applications in the field of non-contact optical temperature thermometry and thermochromic.

Micro-Kelvin Resolution at Room Temperature Using Nanomechanical Thermometry.

Ultrahigh sensitivity temperature measurement is becoming increasingly relevant for different scientific and technological fields from fundamental physics to high-precision engineering applications. Here, we demonstrate the use of a nanomechanical resonator—free standing silicon nitride membranes with thicknesses in the nanoscale—for room temperature thermometry reaching an unprecedented resolution of 15 μK. These devices were characterized by using an interferometric system at high vacuum, where there are only two possible mechanisms for heat transfer: thermal conductivity and radiation. While the expected behavior should be to decrease the frequency of the mechanical resonance due to the thermoelastic effect, we observe that the nanomechanical response can be both positive and negative depending on the thermal flux: a heat point source always shifts the mechanical resonance to lower frequencies, while a distributed heat source shifts the resonance to higher frequencies.

Multiparametric luminescence thermometry from Dy3+, Cr3+ double activated YAG

The multiparametric luminescence thermometry with Dy3+, Cr3+ double activated yttrium aluminium garnet – YAG is demonstrated. Phospors were synthesized via Pechini method and their structure is confirmed by X-ray diffraction analysis. Mean crystallite size of powders was calculated to be ~22 nm. Morphology was investigated using scanning electron microscopy showing combination of dense, different size chunks constituted of spherical particles bellow 50 nm in size. Photoluminescence emission spectra of the Dy3+, Cr3+ double activated YAG consist of blue and yellow Dy3+ emissions and the broad, deep red Cr3+ emission. The decrease in the Dy3+ emission intensity with the increase in the Cr3+ content indicates the efficient energy transfer from Dy3+ to Cr3+ of ~90%. Temperature-dependant photoluminescence emission measurements are performed under 484 nm and 582 nm excitation in the steady-state domain and in the 175 K–650 K temperature range. The noted alterations of luminescence with temperature present an excellent base for studying the multiparametric temperature readouts. The luminescence intensity ratio, the most frequently exploited luminescent thermometry temperature readout method, was tested using: i) the combination of Dy3+ and Cr3+ emissions, ii) using the double excitation approach, and iii) using Cr3+ emission only, with relative sensitivities of 0.64 %K−1 at 175 K, 0.96 %K−1 at 200 K and 2.2 %K−1 at 200 K, respectively.

Performance improvement in temperature thermometry using data analytics - A nuclear power plant perspective

The power density of the nuclear reactor core is high. In the event of inadequate cooling of Fuel subassembly (FSA), the fuel-clad temperature can increase to a high value leading to clad rupture. Hence, it is very important to detect core anomalies with adequate and suitable instrumentation. It is also required to monitor continuously the adequacy of reactor core cooling and initiate suitable safety actions in case of any abnormality.K-Type Thermocouples are normally used for measuring the core temperature. Computer based Core temperature-monitoring system is provided for acquiring the temperature signals, detection of core anomalies, error in core loading, fuel enrichment error and fuel orifice error. The control system monitor the temperature and provides signals for safety system to initiate protective action in case of incidents. These safety actions prevent the clad hot spot and fuel temperature from reaching the design safety limits.Hence, it is necessary to factor in the performance uncertainties of the safety instrumentation so that the process is operated efficiently within the limiting conditions of operation, limiting safety settings and the design safety limits. The errors and uncertainties of the thermocouples, signal processing electronics and the display systems shall be quantitatively estimated to implement an efficient operation strategy and optimize the requirements of calibration & ageing management.This paper deals with application of data analysis techniques to analyze the performance characteristics of core temperature monitoring thermocouples, estimate errors and suggest correction factors so that the requirements of availability and reliability are met within the actual safety limits for the system in a nuclear power reactor. The challenges in electronic calibration of measurement channels are discussed in view of distributed locations. The uncertainties and errors in thermocouple sensors are analysed using data analytics models and an integrated methodology of compensating for overall uncertainties in the system is proposed based on the analysis.

NIR luminescence lifetime nanothermometry based on phonon assisted Yb3+-Nd3+ energy transfer.

Luminescence thermometry in biomedical sciences is a highly desirable, but also highly challenging and demanding technology. Numerous artifacts have been found during steady-state spectroscopy temperature quantification, such as ratiometric spectroscopy. Oppositely, the luminescence lifetime is considered as the most reliable indicator of temperature thermometry because this luminescent feature is not susceptible to sample properties or luminescence reabsorption by the nanothermometers themselves. Unfortunately, this type of thermometer is much less studied and known. Here, the thermometric properties of Yb3+ ions in Nd0.5RE0.4Yb0.1PO4 luminescent temperature probes were evaluated, aiming to design and optimize luminescence lifetime based nanothermometers. Temperature dependence of the luminescence lifetimes is induced by thermally activated phonon assisted energy transfer from the 2F5/2 state of Yb3+ ions to the 4F3/2 state of Nd3+ ions, which in turn is responsible for the significant quenching of the Yb3+:2F5/2 lifetime. It was also found that the thermal quenching and thus the relative sensitivity of the luminescent thermometer can be intentionally altered by the RE ions used (RE = Y, Lu, La, and Gd). The highest relative sensitivity was found to be SR = 1.22% K−1 at 355 K for Nd0.5Y0.4Yb0.1PO4 and it remains above 1% K−1 up to 500 K. The high sensitivity and reliable thermometric performance of Nd0.5La0.4Yb0.1PO4 were confirmed by the high reproducibility of the temperature readout and the temperature uncertainty being as low as δT = 0.05 K at 383 K.

Near-infrared light-mediated Er3+ and Yb3+ co-doped CaTi4O9 for optical temperature sensing behavior

In present report, CaTi4O9: 1 at% Er3+, 1 at% Yb3+ phosphors have been synthesized via sol-gel method and reported herein for its temperature sensing performance. XRD spectra confirms high crystallinity and successful inclusion of rare earth (RE) ions into CaTi4O9 as the dopant ions do no induce any change in the peak position. The X-ray diffraction analysis indicates that the host calcium titanate exhibits hexagonal crystal structure. The green up-conversion (UC) emission observed using 980 nm diode laser excitation. Since, Er3+ ion has ladder type energy levels, thereby it receives energy from Yb3+ ion by excited state absorption and energy-transfer up-conversion processes. Furthermore, the Er3+ ion has two temperature sensing levels 4S3/2→4I15/2 (550 nm) and 2H11/2→4I15/2 (525 nm). Therefore, temperature dependent up-conversion spectra illustrate good temperature sensitivity for present phosphor. The sensitivity of above mentioned phosphor has been evaluated with temperature from 300K to 500K, which shows the suitability of the phosphor for developments in temperature thermometry.

High Pressure optical nanothermometer based on Er3+ photoluminescence

The optical properties of a sparsely investigated material, LaGdO3 doped with Er3+, are explored regarding its suitability as nanothermometer. Besides its excellent capabilities for dielectric applications, when doping with Er3+, this material provides a highly efficient up-conversion photoluminescence (PL) for high temperature thermometry at high pressure due to its structural stability. LaGdO3 belongs to the perovskite-type ABO3 compounds with a B-type monoclinic C2/m space group (a = 14.43 Å; b = 3.69 Å; c = 9.00 Å; and β = 100.70º) at ambient conditions. It undergoes a structural phase transition to a hexagonal phase at 3 GPa yielding a notable PL enhancement, thus enabling it as a potential high-pressure high-temperature nanothermometer.

Controlled Release of Therapeutics from Thermoresponsive Nanogels: A Thermal Magnetic Resonance Feasibility Study.

Thermal magnetic resonance (ThermalMR) accommodates radio frequency (RF)-induced temperature modulation, thermometry, anatomic and functional imaging, and (nano)molecular probing in an integrated RF applicator. This study examines the feasibility of ThermalMR for the controlled release of a model therapeutics from thermoresponsive nanogels using a 7.0-tesla whole-body MR scanner en route to local drug-delivery-based anticancer treatments. The capacity of ThermalMR is demonstrated in a model system involving the release of fluorescein-labeled bovine serum albumin (BSA-FITC, a model therapeutic) from nanometer-scale polymeric networks. These networks contain thermoresponsive polymers that bestow environmental responsiveness to physiologically relevant changes in temperature. The release profile obtained for the reference data derived from a water bath setup used for temperature stimulation is in accordance with the release kinetics deduced from the ThermalMR setup. In conclusion, ThermalMR adds a thermal intervention dimension to an MRI device and provides an ideal testbed for the study of the temperature-induced release of drugs, magnetic resonance (MR) probes, and other agents from thermoresponsive carriers. Integrating diagnostic imaging, temperature intervention, and temperature response control, ThermalMR is conceptually appealing for the study of the role of temperature in biology and disease and for the pursuit of personalized therapeutic drug delivery approaches for better patient care.

Transcranial Magnetic Resonance Imaging-Guided Focused Ultrasound Treatment at 1.5 T: A Retrospective Study on Treatment- and Patient-Related Parameters Obtained From 52 Procedures

To present a retrospective analysis of patient- and sonication-related parameters of a group of patients treated with a transcranial magnetic resonance imaging-guided focused ultrasound (tcMRgFUS) system integrated with a 1.5-T MRI unit. The data obtained from 59 patients were retrospectively reviewed for this study. The following data were mainly collected: skull density ratio (SDR), skull area (SA), transducer elements (Tx), and estimated focal power at target (FP). For each treatment stage, we calculated the number of sonication (Sn), sonication power (Sp), measured power (Smp), sonication duration (Sd), energy (E), measured energy (Em), maximum temperature (Tmax), and MR thermometry plane orientation. Furthermore, the time delay between each sonication (St) and the total treatment time (Tt) were recorded. Fifty-two patients (40 males and 12 females; age – 64.51 ± SD 11.90; range 26–86), who underwent unilateral Vim thalamotomy (left = 50, 96.15%; right = 2, 3.85%) for medication refractory essential tremor (n=39; 78%) or Parkinson tremor (n=13; 22%) were considered. A total of 1068 (95.10%) sonication were included in our final analysis (average Sn per treatment: 20.65 ± 6.18; range 13–41). The energy released onto the planned target was found to decrease with the SDR for all temperature ranges. A positive correlation was observed between the slope of Tmax vs. Em plot and the SDR (R2=0.765; p<0.001). In addition, the Tmax was positively correlated with SDR (R2=0.398; p<0.005). On the contrary, no significant correlation was found between SDR and SA or Tx. An analysis of the MR Thermometry scanning plane indicated that, at our site, the axial and the coronal planes were mostly used. Our results confirm the factors that significantly influence the course of a tcMRgFUS procedure even when a 1.5-T MRI scanner is used for procedure guidance. The experience we gained in this study indicates that the SDR still remains one of the most significant technical parameters to be considered in a tcMRgFUS procedure. The possibility of prospectively setting the sonication energy according to the presented curves of energy delivery as a function of SDR for each treatment stage could provide a further understanding and awareness of this technology.

Clumped isotopic signatures in land-snail shells revisited: Possible palaeoenvironmental implications

It is crucial to understand the clumped isotope compositions (Δ47) of modern land-snail shells and their relationship with environmental parameters for palaeoenvironmental-studies. Previous studies have shown significant variations in relationships between snail-shell Δ47 and ambient air temperature, and the reliability of shell Δ47 in indicating air temperature remains uncertain. This study examined the shell Δ47 from China with mean annual temperatures ranging from 5 to 23 °C and the snail body fluid δ18O estimated from shell δ18O and Δ47-derived temperatures. For all snails studied in this study, site-averaged Δ47 values yield snail calcification temperatures ranging from 25 to 36 °C, which are higher-than-expected in either environmental temperatures or estimated snail activity temperatures. We suggest that snails up-regulate their body temperatures towards their preferred living conditions likely through behaviour or/and physiology adaptation, especially at low temperature environments, which is likely significant than observed previously. Δ47 disequilibrium associated with CO2 degassing during snail calcification is potential but it could possibly be corrected by using an empirical calibration based on natural land-snails. Varying degrees of δ18O enrichment (>8‰) relative to rainwater are observed in snail body fluids, possibly due to variable evaporation during shell calcification. Coupled with model calculations, the relationship between snail body fluid δ18O and rainwater δ18O could be improved by using Δ47-based temperature and δ18O thermometry, if snails prefer to be active at ~90% relative humidity. This study highlights the importance of land-snail shell Δ47 coupled with shell δ18O to indicate temperature and rainwater δ18O at micro-environments scales.

Chapter 29 - Body temperature and clinical thermometry

In this chapter, the nuance of body temperature is explored in the context of contemporary clinical medicine and technology. It takes the reader through the concept of body and shell as a route to explain the variety of temperature measurements that are observed in health and disease and the interdependence between skin and core temperature in maintaining thermal stability and thermal comfort perception. Methods for the measurement of temperature using different thermometer devices are discussed from the perspective of fundamental clinical assessment and vital signs, temperature monitoring and measurement for life-critical decision making, thermometry in mass screening, and to the future with advances in thermometry and thermography in new applications for diagnosis.

Enhancement of low-temperature thermometry by strong coupling

We consider the problem of estimating the temperature $ T $ of a very cold equilibrium sample. The temperature estimates are drawn from measurements performed on a quantum probe strongly coupled to it. We model this scenario by resorting to the canonical Caldeira-Leggett Hamiltonian and find analytically the exact stationary state of the probe for arbitrary coupling strength. In general, the probe does not reach thermal equilibrium with the sample, due to their non-perturbative interaction. We argue that this is advantageous for low temperature thermometry, as we show in our model that: (i) The thermometric precision at low $ T $ can be significantly enhanced by strengthening the probe-sampling coupling, (ii) the variance of a suitable quadrature of our Brownian thermometer can yield temperature estimates with nearly minimal statistical uncertainty, and (iii) the spectral density of the probe-sample coupling may be engineered to further improve thermometric performance. These observations may find applications in practical nanoscale thermometry at low temperatures---a regime which is particularly relevant to quantum technologies.

Influence of codoping on the luminescence properties of YAG:Dy for high temperature phosphor thermometry

The effects of codoping on the temperature-dependent luminescence of YAG:Dy were investigated for application in high temperature thermometry. YAG:Dy is a well-known thermographic phosphor suitable for high temperature measurements. However, its decay time is too long for studying temperatures in fast transient technical processes. Codoping is a known method for increasing the signal intensity and for decreasing luminescence decay times. Five co-doped samples with three different sensitizers, namely Tm, Tb and Pr were synthesized by solid-state method. Changes in spectral emission behavior and temperature dependent decay time are presented up to 1600K. The intensity ratio used for temperature measurements was similar for all samples, and decay time decreased for all codopings. Codoping by Tm decreased signal intensity considerably, thus YAG:Dy,Tm is not suitable for high temperature measurements. However, codoping YAG:Dy with Tb and especially Pr resulted in improved luminescent characteristics, and these phosphors are promising for high temperature phosphor thermometry.