Temperature Sensitivity Research Articles

Changes in SOC, pH, and Ca associated with microorganism mediated SOC mineralization and temperature sensitivity following vegetation restoration in karst regions

Changes in SOC, pH, and Ca associated with microorganism mediated SOC mineralization and temperature sensitivity following vegetation restoration in karst regions

Maximizing temperature sensitivity in a one-dimensional photonic crystal thermal sensor

This paper focuses on a defective one-dimensional photonic crystal thermal sensor with fabricated layers of gallium nitride, glycerin, and air. The transmission features of this sensor have been presented based on the transfer matrix approach using MATLAB software. Interest in the sensor’s sensitivity to temperature variation is for the sake of the photonic bandgap behavior of the 1D photonic crystal and the thermo-optic effect of glycerin must be preserved over a long time in protecting archaeological artifacts. In this direction, theoretical modeling together with numerical simulation studies are conducted to optimize the refractive index of GaN to enhance sensitivity. This work is going to evaluate the performance of the sensor in terms of the shift in the transmission spectrum of the sensor with the imposition of changes in temperature. The effect of the thickness of the defect layer together with the incident angle on the performance of the sensor will be discussed further. Sensor sensitivities are about 10 nm/°C, with a quality factor reaching a high value of 35,443 at an incident angle of 30°, while sensitivities at an incident angle of 65° have 20 nm/°C and a quality factor of 14,723.

Mechanical behaviour of dual-phase SS301 under cryogenic conditions

The present work is the first comprehensive investigation of the cryogenic behaviour of dual-phase SS301 stainless steel over an extensive temperature range, including 20 K, 30 K, 40 K, 77 K, 120 K, 150 K, 170 K, and 300 K. The range of temperature involved in this study renders critical insights on the temperature sensitivity of the mechanical properties of SS301, such as yield strength, and ultimate tensile strength. This work notably unravels that the ductility and toughness of dual-phase SS301 remain largely unchanged between cryogenic and room temperatures owing to the similar level strain-induced transformation of martensite, and the resulting comparable phase-fractions. Furthermore, in addition to the two-stage serrations which are generally observed in discontinuous plastic-deformation, the present investigation reveals that the yield at 40 K accommodates four-stage serrations. However, interestingly, the four-stage of the serrations at 40 K progressively transition into two-stages as the deformation proceeds. Ultimately, the current work elucidates the mechanical behavior of dual-phase SS301 at cryogenic temperatures, in contrast to the more commonly analyzed austenitic stainless steels.

Comparative analysis of global urban land surface phenology between the MODIS and VIIRS products and extraction methods.

The reliability of land surface phenology (LSP) derived from satellite remote sensing is crucial for obtaining accurate estimates of the phenological response of vegetation to future climate change in urban ecosystems. Differences in phenological definition and extraction methodology using remote sensing can generate systemic errors in estimating the phenological temperature sensitivity to predict the biological response of vegetation. Here, we evaluated the start of the season (SOS), the end of the season (EOS), and the growing season length (GSL) between the Terra and Aqua combined Moderate Resolution Imaging Spectroradiometer (MODIS) Land Cover Dynamics (MCD12Q2) and the Suomi National Polar-Orbiting Partnership NASA Visible Infrared Imaging Radiometer Suite (VIIRS) Land Cover Dynamics (VNP22Q2) over 1470 urban clusters worldwide. We found that the availability of valid phenological estimation in urban areas was low across climates, and cities without valid phenological data were mainly distributed in tropical and dry climate zones. The phenological comparison for each urban cluster worldwide revealed significant differences between the two products. For SOS, EOS, and GSL, only a small proportion of urban clusters (6.01%, 3.54%, and 1.50%, respectively) exhibited R2 surpassing 0.5, and approximately 31.63%, 37.37%, and 58.57% showed the RMSD values exceeding two weeks. These results remained consistent and robust across various climates, latitudinal gradients, and valid pixel proportions. We also revealed discrepancies in the inter-annual variability of LSP between the two products. These disparities in phenological metrics directly lead to systematic uncertainties in the measurements of temperature sensitivity. Furthermore, urban phenology disparities primarily arise from the different phenology definitions employed by the two products. Standardizing the definition of phenology metrics extraction from remote sensing data is crucial to the comprehensive understanding of phenological responses to urban environments, which thus provides referencing resources for studying how future environmental changes affect vegetation in natural ecosystems.

Effects of wildlife conservation and land use intensification on heterotrophic soil respiration and temperature sensitivity (Q10) in semiarid savannas

Effects of wildlife conservation and land use intensification on heterotrophic soil respiration and temperature sensitivity (Q10) in semiarid savannas

Fast-decaying tree litter reduces the temperature sensitivity of soil carbon decomposition by increasing microbial necromass carbon

Fast-decaying tree litter reduces the temperature sensitivity of soil carbon decomposition by increasing microbial necromass carbon

Higher endogenous labile organic carbon decreases the temperature sensitivity of soil organic matter decomposition in two subtropical forests

Higher endogenous labile organic carbon decreases the temperature sensitivity of soil organic matter decomposition in two subtropical forests

Global decline in net primary production underestimated by climate models

Marine net primary production supports critical ecosystem services and the carbon cycle. However, the lack of consensus in the direction and magnitude of projected change in net primary production from models undermines efforts to assess climate impacts on marine ecosystems with confidence. Here we use contemporary remote sensing net primary production trends (1998–2023) from six remote sensing algorithms to discriminate amongst fifteen divergent model projections. A model ranking scheme, based on the similarity of linear responses of net primary production to changes in sea surface temperature, chlorophyll-a and the mixed layer, finds that future declines in net primary production are more likely than presently predicted. Even the best ranking models still underestimate the sensitivity of declines in net primary production to ocean warming, suggesting shortcomings remain. Reproducing this greater temperature sensitivity may lead to even larger declines in future net primary production than presently considered for impact assessment.

Study on the cooling effect of the parallel perforated ventilation subgrade in permafrost regions based on the numerical model.

The runway in permafrost regions has remarkable temperature sensitivity. Therefore, this paper puts forward to the parallel perforated ventilation subgrade. The reliability and validity of the finite element model of the runway with the parallel perforated ventilation subgrade are verified by comparing with the previous studies. And the cooling effect of the parallel perforated ventilation subgrade is analyzed. Results show that the parallel perforated ventilation subgrade has a significant cooling effect on the pavement and has little cooling effect in the natural ground. Compared with the non-ventilation subgrade, temperature time-history curves for the parallel perforated ventilation subgrade change periodically each year and are gradually lower with the growth of time. Temperature-depth curves for the parallel perforated ventilation subgrade change significantly at the insulation layer, the crushed rock layer, and the perforated ventilation. The air velocity and working time of the parallel perforated ventilation have no effect on the temperature of the surface layer, base layer, and subbase layer, have little effect on the temperature of the insulation layer, and have great effect on the temperature of the crushed rock layer and subgrade. This study provides scientific support for the design, construction, and maintenance of the runway in permafrost regions.

Femtosecond Laser‐Written Invisible Sensors in Architectural Glass and Their Impact on Strength

AbstractMonitoring architectural glass is becoming increasingly important due to its transition from small infill panels to large, load‐bearing applications, but traditional sensors are visually unappealing for use with transparent materials. This study explores the integration of waveguide Bragg gratings (WBG) into 4 mm thick soda lime silicate architectural glass using femtosecond laser technology, creating invisible optical sensors within the bulk. This method furthermore protects the sensors from surface damage. We report on the optimization and characterization of laser‐written waveguides in this type of glass, achieving low‐loss single‐mode waveguides up to 25 cm long with a propagation loss of 0.52 dB cm−1 at 1550 nm wavelength. Furthermore, WBGs are realized showing a 12.8% peak reflectivity and 115 pm−3 dB bandwidth. A demonstrator consisting of a 25 cm‐long architectural glass plate with a WBG in the center connected to the edge via a single‐mode waveguide, shows a strain sensitivity of 1.20 pm μɛ−1 and a temperature sensitivity of 13.5 pm °C−1. Importantly, mechanical testing confirms that the waveguides do not compromise the strength of the glass which is crucial when subjected to loads. These findings underscore the potential of this technology for structural health monitoring of glass structures.

Investigation on Dynamic and Static Modulus and Creep of Bio-Based Polyurethane-Modified Asphalt Mixture

The superior mechanical qualities of polyurethane have garnered increasing attention for its application in modifying asphalt mixtures. However, polyurethane needs to use polyols to cure, and polyols need to be produced by petroleum refining. As we all know, petroleum is a non-renewable energy source. In order to reduce oil consumption and conform to the trend of a green economy, lignin and chitin were used instead of polyols as curing agents. In this paper, a biological polyurethane-modified asphalt mixture (BPA-16) was designed and compared with a polyurethane-modified asphalt mixture (PA-16) and a matrix asphalt mixture (MA-16). The viscoelastic characteristics of the three asphalt mixtures were evaluated using dynamic modulus, static modulus, and creep tests. The interplay between dynamic and static modulus and frequency is examined, along with the variations in the correlation between dynamic and static modulus. The creep behavior of the mixture was ultimately examined by a uniaxial static load creep test. The findings indicate that the dynamic modulus of BPA-16 exceeds those of PA-16 and MA-16 by 8.7% and 30.4% at 25 Hz and −20 °C, respectively. At 25 Hz and 50 °C, the phase angle of BPA-16 decreases by 26.3% relative to that of MA-16. Lignin and chitin, when utilized as curing agents in place of polyol, can enhance the mechanical stability of asphalt mixtures at low temperatures and diminish their temperature sensitivity. A bio-based polyurethane-modified asphalt mixture can also maintain better elastic properties in a wider temperature range. At −20–20 °C, the dynamic and static moduli of BPA-16, PA-16 and MA-16 are linear, and they can be converted by formula at different frequencies. The failure stages of BPA-16, PA-16, and MA-16 are not observed during the 3600 s creep duration, with BPA-16 exhibiting the least creep strain, indicating that lignin and chitin enhance the resistance to permanent deformation in PU-modified asphalt mixes.

Radon on Mars and the Moon derived from Martian and lunar meteorites

The radioactive gas radon-222, a fluid and aerosol tracer in Earth’s lithosphere and atmosphere, can also reveal subtle rock physics processes in extraterrestrial environments, such as those involving water, but remains poorly constrained in planetary bodies due to the limited number of samples available. Here we measure the effective radium-226 concentration (ECRa) of six Martian and nine lunar meteorites to derive radon source terms for Martian and lunar rocks. ECRa values are 0.029–0.78 and 0.045–0.80 Bq kg−1 for Martian and lunar meteorites, respectively (0.041 ± 0.003 Bq kg−1 for falls and 0.28 ± 0.02 Bq kg−1 for finds), lower than most terrestrial rocks but similar to other meteorites and terrestrial primitive basalts. The effect of terrestrial alteration on ECRa and its temperature sensitivity are also determined experimentally. Radon emanation coefficient values are 2.1–17% (mean: 8.1 ± 2.5%) for Martian meteorites and 0.43–11% (mean: 5.5 ± 1.0%) for lunar meteorites. Mean estimated surface radon fluxes for Mars and the Moon are 0.16–0.60 and 0.33–0.44 mBq m−2 s−1 (78–280 and 160–210 atoms m−2 s−1), respectively, much lower than on Earth (21 mBq m−2 s−1 or 104 atoms m−2 s−1). Our meteorite analyses constrain radon emanation on Mars and the Moon and provide a basis for current and future in-situ measurements.

Complex Impedance measurement and saturation energy analysis of optical transition-edge sensors

Abstract Transition Edge Sensors (TESs) are highly sensitive thermal detectors that operate across a wide frequency range, from millimeter waves to gamma rays. For optical single-photon TES detectors, a high energy resolution and large saturation energy are required, primarily limited by factors such as heat capacitance and temperature sensitivity, αI. In this study, we evaluated TES devices of varying sizes by conducting complex impedance measurements using transfer function calibration, revealing that our titanium-based TES exhibits higher heat capacities compared to theoretical values. We obtained the measured and theoretical time constants, energy resolutions, and saturation energies for the different-sized TESs, notably constructing histograms from pulse area integral analysis. Our devices achieved an optimal energy resolution of 0.2 eV, with the largest TES demonstrating an energy resolution of 0.34 eV, a saturation energy of 35 eV and the ability to discriminate up to 20 photons at 438 nm. These results provide valuable insights for optimizing TES performance in precise photon detection.

Polymer-Layered Optical Wearable (PLOW) for Healthcare Applications: Temperature and Stretching Monitoring.

Thermal and stretching characteristics are crucial variables in healthcare, robotics, and human-machine interaction applications. Here, we present a single-mode fiber-based, balloon-shaped, single- and dual polymer-layered optical wearable (PLOW) system that can sense both temperature and stretching. These two types of PLOWs are compared in terms of their detection performance across all criteria. Dual polymer-based systems have a substantial temperature sensitivity of -1.39 nm/°C, while single polymer ones show a sensitivity of -0.18 nm/°C. The increased sensitivity is attributed to the higher thermo-optic coefficient of the bipolymer (polymer jacket and PDMS) encasing. In terms of stretching sensing, single PLOWs beat dual ones for both longitudinal and lateral stretching due to the large change in shape variable at the same extrusion pressure in single PLOWs. The fast temporal response, high-temperature tolerance, long-term stability, and stretching sensitivity of both PLOWs make them ideal for real-time monitoring of skin temperature, wrist pulse, voice recognition, and different mechanical stimuli. These measures are critical for correctly assessing invasive human health parameters. We believe that these technologies will hold tremendous promise in wearable optical systems, with applications ranging from healthcare to humanoid robotics.

A niobium nitride superconducting hot electron bolometer direct terahertz detector working at 9 K

Increasing the bath temperature of the hot electron bolometer (HEB) while ensuring sensitivity could expand the application field and reduce the system complexity and cost. This study proposed and prepared a suspended NbN/Nb5N6 HEB with doubled bath temperature and undegraded sensitivity compared to NbN HEB. Under the bath temperature of 9 K, the optical noise equivalent power of the system was still of the order of pW/Hz1/2. Moreover, the influence of thermal relaxation on the device sensitivity was simulated. The results would provide a pathway for improving the bath temperature and detector sensitivity through fine adjustments of the thermal boundaries.

Optimization of Erbium-Doped Fiber to Improve Temperature Stability and Efficiency of ASE Sources

The ASE (Amplified Spontaneous Emission) light source, based on erbium-doped fiber (EDF), is a broadband light source with advantages such as high power, excellent temperature stability, and low coherent light generation. It is widely used in the field of fiber optic sensing. However, traditional ASE sources suffer from temperature sensitivity and low efficiency, which can compromise the accuracy and stability of the output light’s average wavelength. This study focuses on optimizing the erbium-doped fiber (EDF) to improve the temperature stability and efficiency of the ASE light source. Through simulations, we found that the appropriate doping concentration and length of the EDF are key factors in enhancing the stability and efficiency of the ASE source. Inorganic metal chloride vapor-phase doping combined with an improved chemical vapor deposition process was used to fabricate the erbium-doped fiber, ensuring low background loss, minimal OH− absorption, and uniform distribution of the erbium ions in the core of the fiber. The optimized EDFs were integrated into the ASE source, achieving a power conversion efficiency of 53.6% and a temperature stability of 0.118 ppm/°C within the temperature range of −50 °C to 70 °C. This study offers a practical approach for improving the performance of ASE light sources and advancing the development of high-precision fiber optic sensing technologies.

Enhanced optical response of n-type doped InAs quantum dots through interface state inactivation

Owing to the wide tuning range, high-temperature stability, flexible design, and fast recovery dynamics, quantum dots (QDs) have been widely used in many research fields, such as lasers, photodetectors, solar cells, and displays. Among these, III–V InAs/GaAs QDs are especially suited for infrared optoelectronic applications due to their strong working stability and enhanced light output efficiency. The doping technique has been admitted as a very effective method to enhance the modal gain and temperature insensitivity for InAs/GaAs QDs-based devices. Additionally, doping could modulate critical optical responses, like light absorption and carrier recovery dynamics, making these QDs ideal for ultrafast applications. In this work, p-type (Be) doping and n-type (Si) doping were introduced into multilayer QDs to mitigate the adverse effects of grown-in interface states, which were verified by temperature-dependent photoluminescence (PL) characterization. The results show a significant increase in PL intensity for n-doped samples, which was attributed to the effective suppression of interface states. This enhancement correlates with doping levels, with PL intensity increasing from 1.71 to 2.72 times as Si concentration rises from 1 × 1018/cm3 to 3 × 1018/cm3. In contrast, p-doped samples show a slight decrease in PL intensity and a 20 nm blueshift in PL emission peak, indicating different interdiffusion behaviors between In and Ga atoms compared to that in n-doped ones. By integrating with distributed Bragg mirrors, QD semiconductor saturable absorption mirrors were developed, where n-doped QDs presented superior performance in mode-locked ultrafast lasers with the shortest pulse width and highest output power.

Broad-Temperature Optical Thermometry via Dual Sensitivity of Self-Trapped Excitons Lifetime and Higher-Order Phonon Anharmonicity in Lead-Free Perovskites.

Broad-temperature optical thermometry necessitates materials with exceptional sensitivity and stability across varied thermal conditions, presenting challenges for conventional systems. Here, we report a lead-free, vacancy-ordered perovskite Cs2TeCl6, that achieves precise temperature sensing through a novel combination of self-trapped excitons (STEs) photoluminescence (PL) lifetime modulation and unprecedented fifth-order phonon anharmonicity. The STEs PL lifetime demonstrates a highly temperature-sensitive response from 200 to 300 K, ideal for low-to-intermediate thermal sensing. In contrast, the Eg phonon mode undergoes significant linewidth broadening due to five-phonon scattering processes, with a distinct nonlinear temperature dependence up to 500 K. This fifth-order anharmonic effect enhances Raman-based temperature sensitivity, yielding a specific sensitivity (Sr) of 0.577% K-1 at 330 K and remaining above 0.5% K-1 at elevated temperatures. This study presents the first evidence of fifth-order anharmonic effects enhancing Raman-based temperature sensitivity, establishing Cs2TeCl6 as a versatile candidate for broad-temperature optical thermometry and opening new avenues for precise non-contact temperature sensing in advanced technological applications.

Blue rings in trees and shrubs as indicators of early and late summer cooling events at the northern treeline

The high temperature sensitivity of pine trees in northern Fennoscandia has led to some of the most reliable tree-ring climate reconstructions in the world for the past millennia. However, wood anatomical anomalies that likely reflect temperature-induced reductions in cell wall lignification, the so-called Blue Rings (BRs), have not yet been systematically investigated in trees and shrubs in northern Europe. Here, we present frontier research on the occurrence of BRs in Pinus sylvestris trees and Juniperus communis (L) s.l. shrubs from the upper treeline in northern Norway (69°N) in relation to instrumental temperature data covering the last ca. 150 years. The highest number of BRs was found in 1902, with 96% of Pinus trees and 68% of Juniperus shrubs showing BRs. These corresponded on average to a 42% vs. 27% proportion of the growth ring in 1902 which was less-lignified in Pinus trees and Juniperus shrubs, respectively. Another peak in BRs recorded for 1877 was more pronounced in Pinus trees (88%) than in Juniperus shrubs (36%), with a lower proportion of less lignified rings. We found the lowest monthly sums of growing degree days in June 1902 and August 1877, resulting in more uniform non-lignified BRs in 1902 than in 1877. Prolonged early growing season cooling shortened the growing season in 1902 and resulted in much thinner cell walls in trees and shrubs than in 1877, which was characterized by extended cooling at the end of the growing season. Also, after 1902 BR, Pinus trees exclusively showed no recovery in the mean cell wall thickness in the following year. Our study provides the first evidence for different impacts of early versus late growing season cooling on cell wall lignification in trees and shrubs at the northern treeline. Using the anatomy of BRs, we demonstrated the potential to refine summer cooling event reconstructions at an intra-annual resolution in northern Fennoscandia and beyond.

Unraveling the response of the apparent temperature sensitivity of ecosystem respiration to rising temperature

Abstract Global warming is expected to intensify carbon loss, as ecosystem respiration rates increase exponentially with rising temperatures. However, a comprehensive analysis of the response of the apparent temperature sensitivity of ecosystem respiration (Q10) to rising temperature is lacking. This study leverages observational data from 254 sites from the FLUXNET2015 and AmeriFlux datasets to address this knowledge gap. We found a strong influence of non-temperature factors on the seasonality of ecosystem respiration. The similar seasonality of this effect and temperature can lead to underestimating or overestimating Q10. In this study, Q10 was quantified using a temporal moving window and a linear-mixed effect model to account for the effects of non-temperature factors on ecosystem respiration. Our results show that Q10 decreases from 1.55±0.24 (mean±one standard error) at 5 ℃ to 1.35±0.18 at 25 ℃ over all sites. The mean slope of Q10 to temperature across all sites is about -0.02 ℃-1. In this study, we found lower values of Q10 and a lower decreasing rate of Q10 with rising temperature compared to previous studies. Our research suggests that Q10 might be systematically overestimated due to the confounding effect of non-temperature factors, potentially leading to overestimated simulation of ecosystem respiration rate. Our study also emphasizes the necessity of developing a process-based model, rather than simply incorporating the influences of non-temperature factors into Q10.