Temperature Sensitivity Research Articles

Hyperbolic map unravels eight regions in temperature volatility regionalization of Mainland China

Abstract Abrupt temperature volatility has detrimental effects on daily activities, macroeconomic growth, and human health. Predicting abrupt temperature volatility and thus diminishing its negative impacts can be achieved by exploring homogeneous regions of temperature volatility and analyzing the driving factors. To investigate the regionalization of temperature volatility in Mainland China, a network constructed by the cosine similarity of temperature volatility series from Mainland China was embedded in hyperbolic space. Subsequently, we partitioned the network on the hyperbolic map using the critical gap method and then found eight regions in all. Ultimately, a network of communities was constructed while the interaction among communities was quantified. This yields a perspective of temperature volatility regionalization that can accurately reflect factors including altitude, climate type, and the geographic location of mountains. Further analysis demonstrates that the regionalization in the hyperbolic map is distinct from provinces and has a realistic basis: communities in southwest China show strong correlations due to the temperature sensitivity to altitude, and communities in northern China show a convergence in the area of Dingxi, Gansu, mainly owing to the strong temperature sensitivity to climate types. As a consequence, node distributions and community divisions in the hyperbolic map can offer new insights into the regionalization of temperature volatility in Mainland China. The results demonstrate the potential of hyperbolic embedding of complex networks in forecasting future node associations in real-world data.

Recycling of flotation residual carbon from coal gasification fine slag through thermal combustion reaction: Insight into the spatial and temporal multi-scale evolution of typical heavy metals

The necessity for a fundamental comprehension of the migration and transformation patterns of heavy metals in the combustion reaction process is paramount to ensure the effective and targeted prevention and control of heavy metal pollution in the context of large-scale energy utilization of waste coal gasification fine slag. This study aims to reveal the fate of typical heavy metals during the combustion reaction of coal gasification fine slag to provide valuable insight for its clean secondary use. In this work, the thermal combustion reactivity of coal gasification fine slag was initially enhanced through froth flotation, and then the spatial and temporal multi-scale evolution of heavy metals in the flotation carbon-rich fraction was investigated by a series of analytical experiments. The results demonstrate a strong correlation between the volatility of typical heavy metals and the combustion reaction process of the flotation carbon-rich fraction. The volatility of V, Ni, Cu, Zn, and Pb is consistently high, of which the volatility of Zn and Pb is consistently above 50%, while the volatility of Cr, Mn, and Ba exhibits greater temperature sensitivity. As the reaction proceeds, the specific surface area of the solid residue expands, and then the smooth and dense mineral particles dissolve into each other to form a cluster structure simultaneously with the collapse of the pore structure, resulting in the volatility of the heavy metals firstly increasing and then decreasing. Furthermore, alkali metals and alkaline earth metal compounds are effective carriers of Cr, Mn, and Ba in the bottom residual. Additionally, the type and number of crystalline minerals in the bottom residual gradually increase as the reaction progresses. This results in the gradual conversion of the heavy metals bound to unstable carbonate minerals and sulphones into more stable chemical forms. The findings provide novel theoretical support and technical guidance for the environmentally sound and efficient utilization of residual carbon in the waste coal gasification fine slag.

Development and evaluation of locust bean gum based in situ gel for ocular delivery of ofloxacin for treatment of bacterial keratitis

One of the drawbacks of conventional ocular dosage forms is their short residence time in the eye. To address this, we propose an ocular in situ gel that adheres to the eye surface for a prolonged period. Locust bean gum (LBG), a galactomannan polysaccharide, exhibits the desired characteristics to serve as a drug carrier for ocular application. However, the gum has not yet been investigated for ocular drug delivery. In this work, we have developed an LBG based in situ gel loaded with ofloxacin and evaluated its drug delivery efficacy through in vitro and ex vivo tests. To confer temperature sensitivity, LBG was grafted with N-isopropyl acrylamide (NIPAAm), and a series of solutions were made with ofloxacin (0.03 % w/v). The solution turned into a gel when the temperature was raised to 37 °C. The safety and efficacy of the developed in situ gels were validated through experiments on rat eyes infected with clinical strains of bacteria. The developed keratitis was completely healed indicating that the grafted LBG can be used as a potential candidate for the development of ocular in situ gel.

A subchannel analysis code for advanced liquid metal fast reactor cores and study on heat transfer characteristics of core geometry parameters

The liquid metal fast reactor represents an important reactor type for the future development of nuclear energy. Accurately modeling and predicting the subchannel flow and heat transfer phenomenon in the rod bundles plays a key role in ensuring core safety. Consequently, a subchannel code suitable for the liquid metal fast reactor is analyzed based on the subchannel analysis code of the Pressurized Water Reactor (PWR). The modified code incorporates various types of liquid metals, such as lead, lead-bismuth eutectic (LBE), and sodium, along with their constitutive models, enhancing the applicability of the liquid metal reactor systems. This code has been verified and validated at several levels, including comparing the code simulation results with other similar subchannel codes results, high-dimensional Computational Fluid Dynamics (CFD) simulations, and experiment data. The sensitivity analysis of core geometric parameters and turbulent mixing coefficients is performed based on the modified version code. The influence of the core geometry, including the rod Pitch to Diameter ratio (P/D), Rod to Wall gap (RTW) and the wire wrap pitch (H) on the sensitivity of outlet temperature has been investigated. The results show that the new subchannel analysis code suitable for liquid metal cooled reactor shows reasonable agreement with the verified and validated results. The geometric parameters, such as P/D, RTW and H have noticeable effects on the outlet temperature difference of the subchannels. Additionally, the outlet temperature distribution in the subchannel is significantly affected by different turbulent mixing coefficients and the distribution of the turbulent mixing coefficient also influenced by the reactor core sizes. Overall, this study could support the rod bundles design and safety analysis in the liquid metal reactors.

Deformation Heat in Tension of Steel Elements

The purpose of the work is an approximate computational and experimental assessment of the specific energy intensity and heat generation at various stages of the material’s operation when the sample is stretched. The paper discusses an approximate method for estimating the specific energy intensity and heat generation at four stages of tensile deformation of a steel sample. Finite element modeling of the work of the manufactured sample under elastic-plastic tension was performed in the ANSYS multifunctional software package. The load in the digital model of the sample was applied according to the full-scale test program. The experiment used flat samples in accordance with GOST 1497, a WAW-1000 testing machine with a 100T microcomputer, and a testo 875i thermal imager with a temperature sensitivity of 0.05 °C at 30 °C. We compared the obtained values on graphs of full-scale tests and a digital model of the samples, identifying critical points and deviation values. Phased loading revealed that the development of destruction occurs on the descending branches and is accompanied by the gradual development of local instability of plastic deformation in the form of a “neck”. It is shown that the heating temperature of the tensile metal can be calculated using the formulas proposed in the paper or by calculation using the ANSYS software package. The test results showed that the surface temperatures of the samples at each stage differ significantly. Four main areas were identified on the graph of changes in the sample surface temperature at a point. An analysis of the existing database of measuring instruments and the ability to obtain and process data was carried out. Experimental values of surface temperatures during continuous quasi-static deformation exceed their calculated values (up to 5 times). The kinetics of changes in the temperature field of the sample surface was carried out using thermographic instruments.

High-Sensitivity Refractive Index Sensing Based on an SNPNS Composite Structure

In this paper, we design and demonstrate an all-fiber-sensitive refractive index (RI) sensor based on the Mach–Zehnder interferometer (MZI). It is constructed by splicing two no-core fibers (NCFs) and a photonic crystal fiber (PCF) between two single-mode fibers (SMFs) to obtain an SMF–NCF–PCF–NCF–SMF composite structure (SNPNS). A study of the effect of varying PCF lengths on the RI reveals that the shorter the length, the higher the sensitivity. The maximum RI sensitivity of 176.9 nm/RIU is attained within the RI range of 1.3365–1.3767 when the PCF length in the SNPNS structure is 3 cm. Meanwhile, the sensor exhibits a high stability in water, with an RSD of only 0.0019% for the interference trough over a duration of two hours. This proposed sensing structure offers the advantages of a large extinction ratio, small size, low temperature sensitivity, and simple fabrication, exhibiting a great potential in RI measurements.

Dy3+-doped niobate phosphor based on charge transfer band red-shift effect: Luminescence thermal stability and temperature sensing performance

The thermal quenching behavior seriously limits the application prospect of phosphors, so it is urgent to improve the thermal quenching behavior of phosphors. It is expected that the red-shift of charge transfer band (CTB) caused by temperature can be used to improve the luminescent stability of phosphor. Therefore, we designed a family of LuNbO4:x%Dy3 (x = 0.25, 1, 2, 5) phosphors based on the characteristic of the red-shift of CTB edge, and investigated the relationship between the red-shift of the CTB edge and the luminescence thermal stability of the phosphor, further broadening the application of this phosphor in temperature sensing. The effects of three different excitation positions, CTB (260 nm), CTB edge red-shift (288 nm) and Dy3+ 4f-4f transition (354 nm), on the luminescence thermal stability of phosphors were also investigated. It was found that only excitation in the red-shift range of CTB edge showed complete antithermal quenching behavior. The LuNbO4:2 %Dy3+ phosphor showed complete antithermal quenching under the excitation of CTB edge, and the comprehensive emission intensity at 573 K is 741 % of that at 298 K. According to the above characteristics, a dual-mode optical thermometry based on fluorescence intensity ratio (FIR) and International Commission on Illumination (CIE) chromaticity coordinates is proposed, in which the maximum relative temperature sensitivity of LuNbO4:x%Dy3+ is 5.04 % K−1 (298 K, FIR) and 3.14 % K−1 (573 K, CIE). Interestingly, when constructing CIE temperature measurement model, we found that LuNbO4:0.25 %Dy3+ phosphor at 260 nm excitation position has obvious color change at each temperature stage, showing temperature visualization characteristics. At 354 nm excitation position, it shows constant white light emission. The excellent optical temperature measurement performance and temperature visualization characteristics of the phosphor shows that it has excellent application potential in optical sensing.

Preparation and performance study of thermo-responsive P(NIPAM-AM-ABP)/keratin composite nanofiber membrane for bio-application

This paper describes a temperature-responsive composite nanofibrous membrane by blending of the P(NIPAM-AM-ABP) (PNAA) nanofiber and the wool keratin (WK) nanofiber. The photo crosslinkable PNAA with the LCST value of 38.1 °C was obtained by free radical copolymerization of the temperature sensitive N-Isopropylacrylamide (NIPAM) monomer, the hydrophilic monomer Acrylamide (AM), and the photo crosslinkable monomer 4-Acryloyloxybenzophenone (ABP). Keratin was extracted from waste wool fiber by reduction method. The PNAA nanofiber (PNAA-NF) and the keratin nanofiber (WK-NF) were electoral spun separately by two-needle parallel spinning, and the obtained composite nanofiber membrane was then crosslinked by UV irradiation and heat treatments to prepare the PNAA/WK nanofiber membrane (PNAA/WK-NFM) with good water tolerance. The result indicated that the photo cross-linkable temperature sensitive PNAA with the LCST of 38.1 °C was successfully synthesized. The obtained PNAA/WK-NFM has a good fibrous morphology and excellent water tolerance. The composite nanofiber membrane showed good reversible temperature sensitivity and temperature responsive drug releasing property due to the PNAA. By combining of the PNAA-NF and WK-NF, the mechanical property of the PNAA/WK-NFM was greatly enhanced in both dry and wet states, and the slow drug releasing property of the membrane was further improved. In-vitro cell culture experiments indicated that the PNAA/WK-NFM has a good biocompatibility with no cytotoxicity. These findings suggested that the PNAA/WK-NFM has a potential application in temperature responsive drug releasing biomaterials.

Displaced thinned single-mode fiber Mach-Zehnder interferometer tested for temperature and curvature applications

This article explains the features and qualities of employing a thinned manufacturing fiber to assemble a Mach-Zehnder interferometer (MZI) for detecting two physical variables: temperature and curvature. The MZI comprises a filter by splicing core-offset sections of a thinned fiber (TF) cladding diameter of 80 μm in an SMF-TF-SMF configuration. The TF splices act as the arms of the MZI, while the mismatch diameter sections serve as optical fiber couplers. The optical spectrum analyzer (OSA) detects the transmitted light and analyzes its optical transmission characteristics, showing 11 peaks of modal interferences into the longitude region. As a result of the experimental arrangement, the curvature and temperature sensitivities are 0.49 nm/m−1, 0.01 nm/°C, and 0.09 nm/°C for temperatures of 0–60 °C and 70–130 °C, respectively. The proposed sensor has potential advantages for measuring refractive index, pH, torsion, curvature, and temperature.

Stronger Impact of Extreme Heat Event on Vegetation Temperature Sensitivity under Future Scenarios with High-Emission Intensity

Vegetation temperature sensitivity is a key indicator to understand the response of vegetation to temperature changes and predict potential shifts in ecosystem functions. However, under the context of global warming, the impact of future extreme heat events on vegetation temperature sensitivity remains poorly understood. Such research is crucial for predicting the dynamic changes in terrestrial ecosystem structure and function. To address this issue, we utilized historical (1850–2014) and future (2015–2100) simulation data derived from CMIP6 models to explore the spatiotemporal dynamics of vegetation temperature sensitivity under different carbon emission scenarios. Moreover, we employed correlation analysis to assess the impact of extreme heat events on vegetation temperature sensitivity. The results indicate that vegetation temperature sensitivity exhibited a declining trend in the historical period but yielded an increasing trend under the SSP245 and SSP585 scenarios. The increasing trend under the SSP245 scenario was less pronounced than that under the SSP585 scenario. By contrast, vegetation temperature sensitivity exhibited an upward trend until 2080 and it began to decline after 2080 under the SSP126 scenario. For all the three future scenarios, the regions with high vegetation temperature sensitivity were predominantly located in high latitudes of the Northern Hemisphere, the Tibetan Plateau, and tropical forests. In addition, the impact of extreme heat events on vegetation temperature sensitivity was intensified with increasing carbon emission intensity, particularly in the boreal forests and Siberian permafrost. These findings provide important insights and offer a theoretical basis and guidance to identify climatically sensitive areas under global climate change.

A Thermosensitive and Degradable Chitin-Based Hydrogel as a Brucellosis Vaccine Adjuvant.

Brucellosis is a zoonotic infectious disease that has long endangered the development of animal husbandry and human health. Currently, vaccination stands as the most efficacious method for preventing and managing brucellosis. Alum, as the most commonly used adjuvant for the brucellosis vaccine, has obvious disadvantages, such as the formation of granulomas and its non-degradability. Therefore, the aims of this study were to prepare an absorbable, injectable, and biocompatible hydroxypropyl chitin (HPCT) thermosensitive hydrogel and to evaluate its immunization efficacy as an adjuvant for Brucella antigens. Specifically, etherification modification of marine natural polysaccharide chitin was carried out to obtain a hydroxypropyl chitin. Rheological studies demonstrated the reversible temperature sensitivity of HPCT hydrogel. Notably, 5 mg/mL of bovine serum albumin can be loaded in HPCT hydrogels and released continuously for more than one week. Furthermore, the L929 cytotoxicity test and in vivo degradation test in rats proved that an HPCT hydrogel had good cytocompatibility and histocompatibility and can be degraded and absorbed in vivo. In mouse functional experiments, as adjuvants for Brucella antigens, an HPCT hydrogel showed better specific antibody expression levels and cytokine (Interleukin-4, Interferon-γ) expression levels than alum. Thus, we believe that HPCT hydrogels hold much promise in the development of adjuvants.

Ultrasensitive and Adjustable Nanothermometers Based on Er3+-Sensitized Core@Shell Nanoparticles for Use in the First Biological Window.

In recent years, intensive research has focused on lanthanide-doped nanoparticles (NPs) used as noncontact temperature sensors, particularly in nanomedicine. These NPs must be capable of excitation and emission within biological windows, where biological materials usually show better transparency for radiation. In this article, we propose that NPs sensitized with Er3+ ions can be applied as temperature sensors in biological materials. We synthesized the NPs through a reaction in high-boiling solvents and confirmed their crystal structure and the formation of core@shell NPs by using X-ray diffraction, high-resolution transmission electron microscopy, and element distribution mapping within the NPs. NaErF4@NaYF4, NaYF4:12.5% Er3+, 2.5% Tm3+@NaYF4, NaYF4:7.5% Er3+@NaYF4, and NaYF4:12.5% Er3+, 2.5% Ho3+@NaYF4 exhibited intense upconversion (UC) emission under 1532 nm laser excitation detectable also in the whole human blood. We propose that this UC results from energy transfer between Er3+ ions and from Er3+ to Tm3+ or Ho3+ codopants. To determine the mechanism of UC, we measured the dependence of the emission band intensities on the laser power densities. Importantly, we also analyzed the temperature-dependent emission of the NPs within the 295-360 K range. Based on the collected emission spectra, we calculated the luminescence intensity ratios (LIRs) of the emission bands to assess their potential for optical temperature sensing. The temperature-sensing properties varied with the concentration of Er3+ ions and the presence of additional Tm3+ or Ho3+ codopants. Depending on the NP composition and the emission bands used for luminescence ratio calculations, the maximum relative temperature sensitivity ranged from 4.55%·K-1 to 1.12%·K-1, with temperature resolution between 0.05 and 2.53 K at room temperature. Finally, as proof of using NPs as temperature sensors in biomedicine, we successfully measured the temperature-dependent emission of NaYF4:7.5% Er3+@NaYF4 NPs dispersed in whole blood under 1532 nm excitation. We demonstrated that the ratio of Er3+ ion emission bands changes with temperature, indicating that these NPs have potential applications in temperature sensing within biological environments. We also confirmed the properties of NPs as temperature sensors by measuring the temperature reading uncertainty and the repeatability of the LIR readings during heating-cooling cycles, thereby confirming the excellent properties of the studied systems as temperature sensors.

Design of photonic crystals for nanokelvin-resolution thermometry

High-resolution thermometry is key for the development of calorimeters, bolometers, and high-stability light sources, as well as for probing dissipation and transport in microelectronics and quantum devices. Achieving nanokelvin-level temperature resolution at room temperature requires using large optical cavities, which are unsuitable for microscale integration. Here we computationally design a one-dimensional photonic crystal Band Edge Thermometer that achieves significant temperature sensitivity by combining: (i) the abrupt variation in optical properties of a direct bandgap semiconductor at the band edge, and (ii) a large quality factor in a resonant photonic structure. Two devices are designed which are constructed from GaAs/AlAs and GaN/AlN multilayer structures. The optimal sensor design features an extremely large thermoreflectance coefficient of 60.6 K−1 and a thermal time constant of 1.1 µs, with a sensor thickness of only 6.7 µm. The projected thermometry noise floor is 84 nK.Hz-½ for the GaAs/AlAs sensor and 35 nK.Hz-½ for the GaN/AlN sensor. The designed sensor architecture is expected to enable a broad range of applications in microcalorimetry and bolometry where a high temperature resolution combined with microscale sensor footprint is required.

PEDOT:PSS-Based Wearable Flexible Temperature Sensor and Integrated Sensing Matrix for Human Body Monitoring.

Flexible temperature sensors have been widely used in electronic skins and health monitoring. Body temperature as one of the key physiological signals is crucial for detecting human body's abnormalities, which necessitates high sensitivity, quick responsiveness, and stable monitoring. In this paper, we reported a resistive temperature sensor designed as an ultrathin laminated structure with a serpentine pattern and a bioinspired adhesive layer, which was fabricated with a composite of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate)/single-wall carbon nanotubes/reduced graphene oxide (PEDOT:PSS/SWCNTs/rGO) and polydimethylsiloxane (PDMS). The temperature sensor exhibited a high temperature sensitivity of 0.63% °C-1, coupled with outstanding linearity of 0.98 within 25-45 °C. Furthermore, it showed fast response and recovery speeds of 4.8 and 5.8 s, respectively, between 25 and 36 °C. It also demonstrated exceptional stability when subjected to stress and bending disturbances with the maximum bending interference deviation of 0.03%. Additionally, it displayed good cyclic stability over a broad temperature range from 25 to 85 °C, and the standard deviation at 25 °C is 0.14%. A series of experiments including blowing detection, respiratory monitoring with or without a mask, and during rest or sleep were conducted to show the potential of the flexible temperature sensors in human body monitoring. Furthermore, a 4 × 4 flexible temperature sensor matrix was integrated to detect and map objects such as wrenches and blood vessels through human hand skin. The results were consistent with those of infrared measurements. The flexible temperature sensor is capable of real-time temperature monitoring and has the potential in tracking human respiration, assessing sleep quality, and mapping the temperature of various objects.

Weak signal ultrafast interrogation of a micro-nano FBG probe sensor based on the hybrid amplified dispersion Fourier-transform method

To elucidate the thermal transport mechanisms at interfaces in micro- and nanoscale electronic devices, real-time monitoring of temperature variations at the microscopic and nanoscopic levels is crucial. Micro-nano fiber Bragg grating (FBG) sensors have been demonstrated as effective in-situ optical temperature probes for measuring local temperatures. Time-stretch dispersion Fourier transform (TS-DFT) that enables fast, continuous, single-shot measurements in optical sensing has been integrated with a micro-nano FBG probe (FBGP) for local temperature sensing. However, its temperature sensitivity and interrogation resolution are limited by the detection sensitivity. In this paper, we propose a hybrid amplified dispersion Fourier transform (ADFT) method to achieve ultrafast interrogation of FBGP’s weak signal. Thanks to the combined effect of TS-DFT and hybrid optical amplification, the reflection signal of the FBGP is amplified, and the wavelength shift of the FBGP sensor is converted to a temporal spacing change between two dispersed pulses through dispersion-induced wavelength-to-time mapping. The proposed method uses a homemade dissipative soliton mode-locked laser as the light source. The hybrid optical amplification technique comprises a L-band erbium-doped fiber amplifier and a distributed Raman amplifier. Their noise figure and net gain for the FBGP are 4.81 dB and 15.93 dB, respectively. In addition, the temperature calibration experiments show that a sampling rate of 51.43 MHz and the maximum temperature measurement error of 1.98°C are achieved within the temperature range of 20.3°C to 97°C. The stability of the net gain provided by the hybrid ADFT system is demonstrated by the coefficient of variation, which ranges from 2.22% to 2.95% in the peak voltage signal of the FBGP. This approach applies to scenarios requiring the handling of weak optical signals, particularly in temperature measurement at the micro-nano scale.

Ultra-sensitive low-temperature luminescent thermometry based on Boltzmann behavior of the Stark sub-levels of Pr3+

The cryogenic sensor is critical for numerous applications such as cryobiology, aerospace space probes, and solid-state superconducting quantum technology. However, it is still a challenge to operate at temperatures below 100 K using luminescent intensity ratio (LIR) thermometers with typical thermal coupling levels based on the Boltzmann mechanism. In this work, a sensitive low-temperature luminescence thermometry approach has been developed utilizing Boltzmann behavior of the Stark sub-levels of Pr3+. Spectral Stark-splitting feature of the 1D2 multiplet of Pr3+ was observed in CaNb2O6: Pr3+ phosphor, and the luminescence intensity ratio (LIR) of high state (Stark sub-level (2)) and low state (Stark sub-level (0)) of 1D2 was employed for temperature sensing, resulting in a notable relative sensitivity (Sr) of 11.3 % K−1 at 60 K. In addition, the intervalence charge transfer (IVCT)-based strategy improves the temperature sensitivity above room temperature with maximum Sr up to 1.54 % K−1 at 420 K. This work consistently demonstrate high sensitivity at low temperature, indicating potential applications in cryogenic temperature sensor. These results provide a route to the development of luminescent thermometers with a high sensitivity at low temperatures and a wide range of operating temperatures.

Fluorescence and temperature sensitive properties of Tb and Eu co-doped 8YSZ thermosensitive ceramic

Incorporating a small amount of rare-earth luminescent elements into thermal barrier coatings is currently the most promising method for determining the temperature distribution of engine blade coatings. In this study, Tb and Eu co-doped 8YSZ ceramic powder (8YSZ:Tb3+&Eu3+) was synthesized using chemical co-precipitation method, and the optimal powder was sintered into ceramic sheet through dry pressing. The phase, morphology, fluorescence properties and temperature sensitivity of 8YSZ:Tb3+&Eu3+ ceramic were studied. Results indicated that 8YSZ:Tb3+&Eu3+ was tetragonal with average grain size ranging from 22 to 28 nm. The luminescence intensity and lifetime of 8YSZ:Tb3+&Eu3+ both reach their maximum when the doping amount of Tb3+ is 1.5 mol%, with the existence of energy transfer from Tb3+ to Eu3+. And the forming processes has little influence on fluorescence performance of 8YSZ:Tb3+&Eu3+ materials. Meanwhile, 8YSZ:1.5Tb&1Eu ceramic reveals excellent temperature sensitivity. At 500 K, the relative sensitivities are 0.519% K-1 and 0.369% K-1 respectively for 8YSZ:1.5Tb&1Eu powder and sheet, while absolute sensitivities are 0.731% K-1 and 0.751% K-1. Consequently, 8YSZ:Tb3+&Eu3+ ceramic is a potential temperature detection material for practical applications.

Structural Uncertainty in the Sensitivity of Urban Temperatures to Anthropogenic Heat Flux

AbstractOne key source of uncertainty for weather and climate models is structural uncertainty arising from the fact that these models must simplify or approximate complex physical, chemical, and biological processes that occur in the real world. However, structural uncertainty is rarely examined in the context of simulated effects of anthropogenic heat flux in cities. Using the Weather Research and Forecasting (WRF) model coupled with a single‐layer urban canopy model, it is found that the sensitivity of urban canopy air temperature to anthropogenic heat flux can differ by an order of magnitude depending on how anthropogenic heat flux is released to the urban environment. Moreover, varying model structures through changing the treatment of roof‐air interaction and the parameterization of convective heat transfer between the canopy air and the atmosphere can affect the sensitivity of urban canopy air temperature by a factor of 4. Urban surface temperature and 2‐m air temperature are less sensitive to the methods of anthropogenic heat flux release and the examined model structural variants than urban canopy air temperature, but their sensitivities to anthropogenic heat flux can still vary by as much as a factor of 4 for surface temperature and 2 for 2‐m air temperature. Our study recommends using temperature sensitivity instead of temperature response to understand how various physical processes (and their representations in numerical models) modulate the simulated effects of anthropogenic heat flux.

Temperature responsive behaviour of SrAl2O4(Eu, Dy):ZnGa2O4(Cr) phosphor-glass composite

The current investigation reports on laser spectroscopy and temperature-sensitive optical response of composite consisting of phosphors (ZnGa2O4:Cr3+ and SrAl2O4:Eu2+, Dy3+) coated on a tellurite glass layer. Based on this composite, a temperature sensor ranging from 298 K to 423 K demonstrates a remarkable temperature sensitivity. Various analytical techniques, such as X-ray Diffraction, Scanning Electron Microscopy, High-Resolution Transmission Electron Microscopy, laser spectroscopy, etc., were employed to analyze the prepared composite. The investigation reveals the presence of ZGO and SrAl phosphors with crystalline sizes of approximately 36 nm and 25 nm, respectively, while the particle size ranges from 400 nm to 600 nm. A dip coating method was utilized to deposit tellurite-phosphor layers on the glass substrate to create a temperature sensor. SEM analysis indicates a layer thickness of around 93 µm. The existence of Eu2+ and Cr3+ ions was confirmed through photoexcitation and emission spectra on a 405 nm laser excitation. The temperature-dependent luminescence was studied using a ratiometric technique, showing a linear variation with temperature, resulting in an excellent temperature sensitivity of about 1.41% K−1 at 298 K. Our preliminary study of the phosphor-tellurite composite suggests significant potential for extensive use in the field of dual-mode highly sensitive optical thermometry.

Reconciling Top‐Down and Bottom‐Up Estimates of Ecosystem Respiration in a Mature Eucalypt Forest

AbstractEcosystem respiration (Reco) arises from interacting autotrophic and heterotrophic processes constrained by distinct drivers. Here, we evaluated up‐scaling of observed components of Reco in a mature eucalypt forest in southeast Australia and assessed whether a land surface model adequately represented all the fluxes and their seasonal temperature responses. We measured respiration from soil (Rsoil), heterotrophic soil microbes (Rh), roots (Rroot), and stems (Rstem) in 2018–2019. Reco and its components were simulated using the CABLE–POP (Community Atmosphere‐Biosphere Land Exchange–Population Orders Physiology) land surface model, constrained by eddy covariance and chamber measurements and enabled with a newly implemented Dual Arrhenius and Michaelis‐Menten (DAMM) module for soil organic matter decomposition. Eddy‐covariance based Reco (Reco.eddy, 1,439 g C m−2 y−1) was slightly higher than the sum of the respiration components (Reco.sum, 1,295 g C m−2 y−1) and simulated Reco (1,297 g C m−2 y−1). The largest mean contribution to Reco was from Rsoil (64%) across seasons. The measured contributions of Rh (49%), Rroot (15%), and Rstem (22%) to Reco.sum were very close to model outputs of 46%, 11%, and 22%, respectively. The modeled Rh was highly correlated with measured Rh (R2 = 0.66, RMSE = 0.61), empirically validating the DAMM module. The apparent temperature sensitivities (Q10) of Reco were 2.22 for Reco.sum, 2.15 for Reco.eddy, and 1.57 for CABLE‐POP. This research demonstrated that bottom‐up respiration component measurements can be successfully scaled to eddy covariance‐based Reco and help to better constrain the magnitude of individual respiration components as well as their temperature sensitivities in land surface models.