Temperature Sensitivity Research Articles

3D reinforcement synergistic effect of embedded nickel‐foam skeleton of polyurethane based on x‐ray CT images: Experimental and finite element analysis

AbstractMonotonic shear tests were performed on Nickel Foam (NF)/Polyurethane (PU) and the results indicated that NF/PU was much greater than the sum of the individual phases in terms of strength and stiffness. Cyclic shear tests were carried out and it was found that shear evolution processes and failure modes of the composite were completely different from the individual phases and the damping properties were greatly improved. Revealing the synergistic mechanism of the 3D continuous metal skeleton on the PU is the key issue to explain the above phenomena. The geometric topology of NF was reproduced using CT technology and a fine‐scale finite element model was established. The mechanical behavior between NF and PU was investigated at the meso‐mechanical scale. The results show that the NF skeleton significantly improves the strength and damping properties of the PU. During cyclic shear, the effects of displacement and temperature on the mechanical and damping properties of the PU are significant. In comparison, the NF skeleton reduces the temperature sensitivity. Based on the analysis of experimental and FEA results, the monotonic and cyclic constitutive models of NF/PU were established. The shear constitutive model under the new loading/unloading criterion has good fitting accuracy and high reliability.Highlights NF/PU properties were investigated by experimental and finite element methods. NF skeleton improves PU performance through the synergistic effect. Synergistic effects were revealed by CT and finite element methods. The R‐O model can fit the shear constitutive model of NF/PU.

Temperature-compensated optical fiber sensor for urea detection based on the femtosecond laser-inscribed process

This study demonstrates a low crosstalk temperature-compensated fiber-based urea sensor based on the hybridization of surface plasmon resonance (SPR) and Mach-Zehnder interferometer (MZI). In this sensing structure, an inscribed waveguide and a semi-open cavity are processed by a femtosecond laser in an optical fiber to excite an SPR signal sensitive to refractive index (RI) and an MZI signal highly sensitive to temperature. Based on the temperature detected by the MZI, the influence of temperature on the SPR signal’s RI detection can be calculated and compensated for using a sensitivity matrix. Based on this precise RI detection of the SPR signal, we have achieved selective urea detection by bio-functionalizing the sensor surface using the urease self-assembly method. The sensitivity and limit of detection for urea are 7.98 (nm/mmol/L) and 0.13 mmol/L, respectively, which are better than those in previous studies. Compared to previous temperature compensation studies, this SPR + MZI sensing method using femtosecond laser processing significantly improves the temperature sensitivity of the MZI signal, which reduces crosstalk and ensures a sufficient working range for the SPR signal. Therefore, this sensor is crucial for advancing high-precision temperature compensation detection, high-sensitivity biological detection, and the future application of the femtosecond laser technology.

Defect-Enabled Superior Negative Thermal Quenching in Palmierite Ba9La(VO4)7:Eu3+ for WLED In Situ Temperature Measuring.

Negative thermal quenching (NTQ) of the phosphors is critically important for both scientific research and practical applications, but the design of efficient NTQ phosphors is still a challenging task. Herein, we report a new strategy for developing NTQ materials by cation-vacancy engineering. Specifically, a new color-tunable Ba9La1-x(VO4):xEu3+ (BLVO:xEu3+) phosphor with abundant intrinsic cation vacancy was developed, exhibiting superior NTQ behavior under 365 nm excitation. The NTQ performance can be modulated via adjusting Eu3+ doping levels, and the emission intensity of Eu3+ ions in the BLVO:0.20Eu3+ phosphor increased by 275% at 473 K compared to room temperature. Furthermore, the reported material emitting bright white light under 365 nm excitation was well-suited for use in white light-emitting diode (WLED) phosphor and fluorescent temperature sensors, exhibiting outstanding color-rendering index (90.1) in lighting and high sensitivity (Sa = 11.83% K-1, Sr = 2.33% K-1) in temperature detecting. Lastly, the operating temperature of WLED at different currents can be monitored and displayed in real time through emission spectroscopy. All of the results demonstrated that the designed NTQ BLVO:xEu3+ can be used as a single-phase white phosphor and optical thermometry. This work provides a fresh perspective for designing high-efficient NTQ phosphors and expands the application of phosphors in WLED in situ temperature detection.

Mechanical behavior of powdered iron aluminide Fe – 28Al manufactured by direct powder forging

This study examines the impact of direct powder forging of powders on the composition, structure, and mechanical properties of iron aluminide Fe–28 at. % Al. During the synthesis and forging of Fe3Al powders, a homogeneous A2 phase is formed at a temperature of 1100 °C. Porosity after forging is 2–2.5 %. Residual pores are predominantly planar in shape and are located at the boundaries of the powder particles. Annealing at 1300 °C improves the quality of interparticle boundaries and all samples exhibit transcrystalline fracture mechanism. Samples forged at 1100 °C and annealed at 1300 °C show maximum strength σbend = 1050 MPa and fracture toughness K1c = 32.3 MPa·m1/2. The yield strength demonstrates anomalous temperature sensitivity with a maximum of 400 °C and at 500 °C. Samples tested at 600 °C show a decrease in yield strength, but a high enough yield point σy ∼400 MPa and a high strengthening rate are very important for high-temperature creep resistance. In creep experiments at a load of 120 MPa at 600 °C, the strain rate varies in the range of 10−7–10−6 s−1, the value of the rate sensitivity n ≈ 4. The main mechanism of creep is dislocation glide.

Temperature and Lateral Pressure Sensing Using a Sagnac Sensor Based on Cascaded Tilted Grating and Polarization-Maintaining Fibers

This study introduces a Sagnac Interferometer (SI) fiber sensor that integrates Polarization-Maintaining Fibers (PMFs) with a Tilted Fiber Bragg Grating (TFBG) for the dual-parameter measurement of strain and lateral pressure. By incorporating a 6° TFBG with PMFs into the SI sensor, its sensitivity is significantly enhanced, enabling advanced multi-parameter sensing capabilities. The sensor demonstrates a temperature sensitivity of −1.413 nm/°C and a lateral pressure sensitivity of −4.264 dB/kPa, as validated by repeated experiments. The results exhibit excellent repeatability and high precision, underscoring the sensor’s potential for robust and accurate multi-parameter sensing applications.

Effect of waste crab shell powder on matrix asphalt

Abstract In order to solve the problems of depleting petroleum asphalt resources and deteriorating pollution of marine products, a systematic study was carried out on the application prospect of waste crab shell (WS) powder as asphalt modifier. In this study, the physical properties of WS powder modified asphalt (WSA) were tested by blending different contents of WS powder into matrix asphalt; the high and low temperature rheological properties of WS powder modified asphalt were characterized by using Dynamic shear rheometer, Bending beam rheometer, and Multiple stress creep recovery test. In addition, the microscopic chemical properties and modification mechanism were analyzed by Differential scanning calorimetry, Fourier transform infrared spectroscopy, Atomic force microscopy, and Scanning electron microscope. It was shown that the WS powder enhanced the viscoelastic properties, temperature sensitivity properties, and permanent deformation resistance of asphalt. In addition, there was no obvious chemical reaction between the WS powder and the matrix asphalt, and no new chemical substances were generated; at the microscopic level, the WS powder and the matrix asphalt had good compatibility. In conclusion, the use of WS powder as a bio-based asphalt modifier to improve the resources and environmental issues have certain prospects.

Response of Different Exogenous Phytohormones to Rice Yield Under Low-Temperature Stress at the Filling Stage

This paper aims to clarify the effects of different exogenous phytohormones on the physiological traits of rice (Oryza sativa L.) at the early stage of irrigation under low-temperature stress. In this study, two types of rice varieties with different temperature sensitivities screened out previously, namely, a cold-tolerant variety (Nan Jing 9108) and a low-temperature-sensitive variety (Hui Liang You 898), were used in pots to simulate the process of low-temperature stress in rice at the early stage of grouting (6–9 days after anthesis) with artificial low-temperature treatments. The experimental treatments were 450 mg L−1 Methyl jasmine acid (MJ), 46 mg L−1 Melatonin (MT), 69 mg L−1 Salicylate (SA), 40 mg L−1 Erythromycin (GA3), 25 mg L−1 Zeatin (Z), 145 mg L−1 Spermidine (SPD), and 5 mg L−1 Abscisic acid (ABA) sprayed on rice before low-temperature stress, while low-temperature treatment without spraying (DK) and conventional planting without spraying (CK) were added as the control. The results showed that compared with the room temperature control (CK, sprayed with deionized water), the low-temperature control (DK, low-temperature treatment, and sprayed with deionized water) all significantly reduced the rice grain yield. Different exogenous hormones sprayed before low-temperature stress could increase rice yield, among which, Z and SPD spraying treatments had a better effect on the yield of Hui Liang You 898, while different exogenous hormone treatments increased the yield of Nan Jing 9108 in an average manner. The Z and SPD treatments increased the yield of Hui Liang You 898 by 24.87% and 26.16% and that of Nan Jing 9108 by 15.87% and 17.80%, respectively. This was mainly attributed to the significant increase in thousand-grain weight and fruiting rate, while there was no significant difference in the number of spikes and number of grains. The different exogenous hormone treatments were able to delay leaf senescence, enhance the photosynthetic production capacity of plants by increasing leaf chlorophyll content, and thus increase the accumulation of photosynthetic assimilation products and population growth rate after flowering. Among them, both Z and SPD treatments resulted in a population growth rate of more than 30% from spike flushing to maturity, which led to a higher dry matter accumulation of the plant at maturity. In addition, in the dry matter distribution of the plant at maturity, the seeds occupied a higher accumulation amount and proportion compared with the respective DK; the SPD treatment resulted in the maximum distribution rate of seeds at maturity of Hui Liang You 898, with an increase of 8.27%, and the Z treatment resulted in the maximum distribution rate of seeds at maturity of Nan Jing 9108, with an increase of 7.34%. At the same time, the Z treatment significantly increased the activities of adenosine diphosphate glucose phosphorylated enzyme (AGP) and starch branching enzyme (SBE) in the grains of both varieties, which resulted in the accumulation of more starch and ultimately increased the rice grain yield. The results verified that different exogenous phytohormones could be used to regulate the insufficiency of grouting caused by low-temperature stress during the grouting and fruiting stages of rice and enriched their agronomic and physiological traits in response at the same time.

The combined influences of local heat application and resistance exercise on the acute mRNA response of skeletal muscle

IntroductionThe development and maintenance of the skeletal muscle is crucial for the support of daily function. Heat, when applied locally, has shown substantial promise in the maintenance of the muscle. The purpose of this study was to determine the combined effects of local heat application and acute resistance exercise on gene expression associated with the human muscle growth program.Materials and methodsParticipants (n = 12, 26 ± 7 years, 1.77 ± 0.07 m, 79.6 ± 15.4 kg, and 16.1 ± 11.6 %BF) completed an acute bilateral bout of resistance exercise consisting of leg press (11 ± 2 reps; 170 ± 37 kg) and leg extension (11 ± 1 reps; 58 ± 18 kg). Participants wore a thermal wrap containing circulating fluid (40°C, exercise + heat; EX + HT) during the entire experimental period and 4 h post-exercise, while the other leg served as an exercise-only (EX) control. Biopsies of the vastus lateralis were collected (Pre, Post, and 4hPost) for gene expression analyses.ResultsIntramuscular temperatures increased (Post, +2.2°C ± 0.7°C, and p < 0.001; 4hPost, +2.5°C ± 0.6°C, and p < 0.001) and were greater in the EX + HT leg post-exercise (+0.35°C ± 0.3°C, and p = 0.005) and after 4hPost (+2.1°C ± 0.8°C and p < 0.001). MYO-D1 mRNA was greater in the EX + HT leg vs. the EX (fold change = 2.74 ± 0.42 vs. 1.70 ± 0.28, p = 0.037). No other genes demonstrated temperature sensitivity when comparing both legs (p > 0.05). mRNA associated with the negative regulator, myostatin (MSTN), decreased post-exercise (p = 0.001) and after 4 h (p = 0.001). mRNA associated with proteolysis decreased post-exercise (FBXO32, p = 0.001; FOXO3a, p = 0.001) and after 4 h (FBXO32, p = 0.001; FOXO3a, p = 0.027).ConclusionThe elevated transcription of the myogenic differentiation factor 1 (MYO-D1) after exercise in the heated condition may provide a mechanism by which muscle growth could be enhanced.

Enhanced visualization of quench dynamics of HTS coils through embedded and distributed fiber optical sensing

The development of high-temperature superconducting (HTS) coils and magnets marks a significant advancement across various fields. To ensure their safety and reliability, thorough performance testing under extreme multi-field conditions is essential. This study introduces an innovative method that utilizes embedded and distributed fiber optical sensing (ED-FOS) in HTS pancake coils for precise real-time thermal monitoring and quench visualization. Incorporated during the manufacturing process, the ED-FOS sensors offer comprehensive and distributed measurements of thermal behavior during quenches. Our experiments demonstrate the ED-FOS effectively detects quenches caused by overcurrent and thermal issues. Unlike conventional techniques that rely on global voltage or magnetic field assessments, ED-FOS provides high spatiotemporal resolution and enhances temperature sensitivity. This capability allows for accurate, real-time identification and tracking of quench locations, which is essential for evaluating reliability and safety, as well as for improving performance. This advancement in HTS coil technology paves the way for wider application in critical fields and significantly enhances the design and management of superconducting coils.

The LpHsfA2-molecular module confers thermotolerance via fine tuning of its transcription in perennial ryegrass (Lolium perenne L.).

Temperature sensitivity and tolerance play a key role in plant survival and production. Perennial ryegrass (Lolium perenne L.), widely cultivated in cool-season for forage supply and turfgrass, is extremely susceptible to high temperatures, therefore serving as an excellent grass for dissecting the genomic and genetic basis of high-temperature adaptation. In this study, expression analysis revealed that LpHsfA2, an important gene associated with high-temperature tolerance in perennial ryegrass, is rapidly and substantially induced under heat stress. Additionally, heat-tolerant varieties consistently display elevated expression levels of LpHsfA2 compared with heat-sensitive ones. Comparative haplotype analysis of the LpHsfA2 promoter indicated an uneven distribution of two haplotypes (HsfA2Hap1 and HsfA2Hap2) across varieties with differing heat tolerance. Specifically, the HsfA2Hap1 allele is predominantly present in heat-tolerant varieties, while the HsfA2Hap2 allele exhibits the opposite pattern. Overexpression of LpHsfA2 confers enhanced thermotolerance, whereas silencing of LpHsfA2 compromises heat tolerance. Furthermore, LpHsfA2 orchestrates its protective effects by directly binding to the promoters of LpHSP18.2 and LpAPX1 to activate their expression, preventing the non-specific misfolding of intracellular protein and the accumulation of reactive oxygen species in cells. Additionally, LpHsfA4 and LpHsfA5 were shown to engage directly with the promoter of LpHsfA2, upregulating its expression as well as the expression of LpHSP18.2 and LpAPX1, thus contributing to enhanced heat tolerance. Markedly, LpHsfA2 possesses autoregulatory ability by directly binding to its own promoter to modulate the self-transcription. Based on these findings, we propose a model for modulating the thermotolerance of perennial ryegrass by precisely regulating the expression of LpHsfA2. Collectively, these findings provide a scientific basis for the development of thermotolerant perennial ryegrass cultivars.

Brown Sequard Syndrome: A Case Report

A very unusual neurological disorder known as Brown-Séquard Syndrome (BSS) may develop when the spinal cord is severed or damaged on one side. Ipsilateral motor paralysis, loss of proprioception, and a lack of pain and temperature sensitivity on the opposite side are hallmarks of this disorder's distinctive pattern of neurological impaired functions. A 45-year-old man with a history of severe injuries who acquired Brown-Séquard Syndrome is the subject of this case report.

Constitutive modeling of the slip-twinning transition in martensitic transformations

Martensite is the result of a diffusionless displacive phase transition. In Fe-based alloys it transforms the FCC to the BCC, BCT, or HCP structures and occurs at high strain rates. It has two typical morphologies, known as lath and plate. A quantitative constitutive description of the slip-twinning transition in the martensitic transformation is presented. It is based on the temperature and strain-rate sensitivities of slip, which are much higher than those for twinning. Thus, twinning becomes a favored deformation mechanism at low temperatures and high strain rates. The Hall-Petch coefficient, for the inclusion of grain size effects, is two times larger for twinning than slip. Constitutive relationships for slip and twinning are presented and applied to the martensitic transformation in steels; the lath-to-plate morphology change observed with increasing carbon content is successfully predicted as a function of grain size by calculations incorporating the two modes of deformation. A simple calculation of the strain rates during martensitic transformation is also provided. This methodology is applied to the Fe–C system and can be extended to the Fe–Ni–C system and to thermoelastic martensites, where twinning is favored over slip to enhance reversibility.

Adjustment of temperature sensitivity using hydrophilic materials to develop superabsorbent polymers based on poly(N‐isopropyl acrylamide) as a temperature‐sensitive material

AbstractPoly(N‐isopropyl acrylamide) (PNIPAm) is a temperature‐sensitive material with a fast temperature response and a low critical solubilization temperature (LCST) of approximately 32°C, but it swells only 20–40 times after absorbing water. To enhance its water‐absorption properties, we introduced hydrophilic monomers into the NIPAm monomer to prepare a ternary copolymerized superabsorbent polymer. In addition, we characterized this copolymer using various techniques and analyzed its temperature‐sensitive and water‐absorbing properties. The results showed that the optimal synthesis conditions consisted of m(NIPAm):m(AMPS) = 4, 1.5% initiator, 0.3% cross‐linking agent, and 1.0% quaternized ammonium chitosan, which ensured the significant temperature sensitivity of the water‐absorbent resin. Under these conditions, the swelling ratio of the water‐absorbing resin reached 235.3 times, the LCST value was 44.6°C, the water retention rate was 84.9% at 25°C after 12 h, and the shrinkage ratio reached 81.7% at 60°C after 3 h, and 97.6% after 12 h. The resulting material could be rapidly dehydrated at high temperatures and presented clear temperature‐sensitive characteristics while maintaining excellent water‐absorbing properties.

Differences in Soil CO2 Efflux and Microbial Community Composition among Slope Aspects in a Mountain Oak Forest

As one of the main terrain factors, the slope aspect generally shows remarkable effects on microclimate and vegetation distribution. The purpose of this study was to determine the potential effects of the slope aspect on soil respiration and the soil microbial community in a temperate mountain forest. A field investigation was carried out in a mountain oak forest located at different slope aspects (northeast, northwest, southeast, and southwest), and soil respiration was continuously measured for 12 months. The soil’s bacterial and fungal taxa were analyzed during the growing season. Our results showed that average soil respiration on the southwest and southeast slope aspects was 72.9% higher than the average on the northeast and northwest slope aspects. The coefficient of variation of soil respiration had the highest value on the northwest aspect (20.9%) and the lowest value on the southeast aspect (6.9%). The southeast slope had significantly higher soil respiration and temperature sensitivity compared to the other three slope aspects. The slope aspect substantially affected the soil’s bacterial and fungal r/K strategy, showing the lowest values on the northwest aspect and the highest values on the southeast aspect. Differences in bacterial r/K, the ratio of microbial biomass carbon (MBC) to soil organic carbon (SOC), and SOC among slope aspects contributed to a 43%, 38%, and 32% variation in soil respiration, respectively. The variation of soil temperature across slope aspects showed an indirect effect on soil respiration through changing bacterial r/K and MBC/SOC. Our findings highlight that terrain plays a critical role in regulating the spatial heterogeneity of soil respiration in mountain forests, which could be explained by the differences in SOC and microbial community composition across slope aspects.

Slow post-fire carbon balance recovery despite increased net uptake rates in Alaskan tundra

Abstract Increasing wildfire occurrence and intensity have immediate effects on northern ecosystems due to combustion of aboveground vegetation and belowground soil organic matter. These immediate impacts have indirect and longer term effects, including deepening of the active layer, changes in soil decomposition rates, and shifts in plant community composition. Despite the increasing fire impacts across the tundra region, the implications of wildfire on ecosystem carbon balance are not well understood. Using paired eddy covariance towers in unburned and burned tundra, we examined the effects of a 2015 wildfire on carbon dioxide and methane fluxes in a wetland tundra ecosystem in the Yukon-Kuskokwim Delta, Alaska, from 2020 to 2022. Wildfire increased the amplitude and variability of carbon uptake and release on seasonal and annual timescales and increased the temperature sensitivity of soil respiration. Seven years post fire, there was annual net uptake in both unburned and burned tundra based on net ecosystem exchange, with the sink strength of burned tundra exceeding that of the unburned tundra by 1.18 to 1.64 times. However, when considering emissions, it would take approximately 86 years to recover the carbon lost from the wildfire itself. Soil moisture was a dominant driver of fluxes and positively associated with higher rates of carbon dioxide uptake and release and methane release. This study underscores the importance of understanding the effects of wildfire-induced shifts on tundra carbon cycling, allowing better predictions of long-term landscape-scale climate feedbacks as the climate continues to warm.

Calibration of TEROS 10 and TEROS 12 electromagnetic soil moisture sensors

AbstractThe TEROS 10 and TEROS 12 are widely used capacitance‐based sensors for measuring volumetric water content (), but few systematic studies of the measurement volume and accuracy of these sensors have been published. The objectives of this study were to (1) calibrate and validate these sensors in mineral soils, (2) determine the sensing volume of each sensor, and (3) evaluate the temperature sensitivity of the sensors. Both sensors were calibrated in the laboratory using columns of packed soil at multiple moisture levels from air‐dry to near saturation. Sensors were validated using additional laboratory and field measurements. The sensing volume was determined by quantifying the response of raw sensor outputs while increasing the level of oven‐dry sand, moist sand (0.100 cm3 cm−3), or water around the sensor in the radial and axial directions. Temperature sensitivity was tested in controlled conditions over a range of temperatures from 2°C to 40°C using encapsulated sensors in packed soil columns at constant . Linear calibration models resulted in mean absolute error ≤0.030 cm3 cm−3 for both sensors during laboratory and field validations. In moist sand, the sensing volume contributing 95% of the maximum sensor response was 439 cm3 for the TEROS 10 and 423 cm3 for the TEROS 12. Both sensors exhibited changes in of ≤0.02 cm3 cm−3 when subjected to a temperature change from 2°C to 40°C. For the soils considered here, both sensors demonstrated accuracy that is likely sufficient for a variety of agricultural and hydrological applications.

Investigation of Improving Stability in Desulfurized-Rubber-Modified Asphalt Using Cerium-Stearate Incorporation

To enhance the compatibility of high-content desulfurized-rubber-modified asphalt (DRMA), the innovative selection of cerium hard acid is employed in this study to investigate its impact on the compatibility of DRMA. The results indicate that when the optimal content of cerium stearate is 1%, the compatibility of the modified asphalt is improved. On the microscopic level, it is observed that the total heat absorption of the modified asphalt decreases and thermal storage stability is enhanced as measured by differential scanning calorimetry. On the macroscopic level, it gives the smallest difference in softening point, optimal storage stability, and best compatibility of the modified asphalt. Additionally, dissolution tests and adhesion tests demonstrate that the inclusion of cerium stearate increases the solubility of desulfurized rubber in asphalt and reduces the stripping rate of desulfurized-rubber particles on the asphalt surface, thereby decreasing phase separation and promoting the compatibility of DRMA. Furthermore, rheological tests indicate that cerium stearate improves both high-temperature and low-temperature performance of the modified asphalt. The addition of cerium stearate increases the dynamic shear modulus of the modified asphalt, maintaining good stability and elasticity under shear loading, with minimal change in low-temperature rheological properties and lower temperature sensitivity, indicating the best compatibility at this point. Finally, molecular-dynamics simulation data indicate that the addition of cerium stearate decreases the parameter difference in the dissolution of modified asphalt and enhances the binding energy of the modified asphalt, demonstrating the feasibility of cerium stearate in promoting the compatibility of modified asphalt.

Pristine Photopolymerizable Gelatin Hydrogels: A Low-Cost and Easily Modifiable Platform for Biomedical Applications.

The study addresses the challenge of temperature sensitivity in pristine gelatin hydrogels, widely used in biomedical applications due to their biocompatibility, low cost, and cell adhesion properties. Traditional gelatin hydrogels dissolve at physiological temperatures, limiting their utility. Here, we introduce a novel method for creating stable hydrogels at 37 °C using pristine gelatin through photopolymerization without requiring chemical modifications. This approach enhances consistency and simplifies production and functionalization of the gelatin with bioactive molecules. The stabilization mechanism involves the partial retention of the triple-helix structure of gelatin below 25 °C, which provides specific crosslinking sites. Upon activation by visible light, ruthenium (Ru) acts as a photosensitizer that generates sulphate radicals from sodium persulphate (SPS), inducing covalent bonding between tyrosine residues and "locking" the triple-helix conformation. The primary focus of this work is the characterization of the mechanical properties, swelling ratio, and biocompatibility of the photopolymerized gelatin hydrogels. Notably, these hydrogels supported better cell viability and elongation in normal human dermal fibroblasts (NHDFs) compared to GelMA, and similar performance was observed for human pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs). As a proof of concept for functionalization, gelatin was modified with selenous acid (GelSe), which demonstrated antioxidant and antimicrobial capacities, particularly against E. coli and S. aureus. These results suggest that pristine gelatin hydrogels, enhanced through this new photopolymerization method and functionalized with bioactive molecules, hold potential for advancing regenerative medicine and tissue engineering by providing robust, biocompatible scaffolds for cell culture and therapeutic applications.

Synthesis and Properties of N1, N3‐di (2,4‐dinitrophenyl) −2‐fluoro‐1,3‐diamino‐4,6‐ Dinitrobenzene and its Analogues

AbstractPolynitrobenzene compounds are a type of heat‐resistant explosives with excellent thermal stability. This study reported three novel energetic compounds, namely compounds N1, N3‐bis(2,4‐dinitrophenyl)‐2‐fluoro‐4,6‐dinitrobenzene‐1,3‐ diamine (3), 2‐fluoro‐4,6‐dinitro‐N1,N3‐bis(2,4,6‐trinitrophenyl)benzene‐1,3‐ diamine (4), and 2‐chloro‐4,6‐dinitro‐N1,N3‐bis(2,4,6‐trinitrophenyl)benzene‐1,3‐ diamine (6). The target compounds were prepared with commercially available 2,3,4‐trifluoronitrobenzene and 2,3,4‐trichloronitrobenzole. The crystalline structures of compounds 3, 4, and 6 were determined by single‐crystal X‐ray diffraction, and the crystal densities (ρ) were calculated to be 1.7585 g cm−3, 1.6651 g cm−3, and 1.7371 g cm−3, respectively. Based on the calculated standard molar enthalpy of formation and crystal densities, the Chapman–Jouguet detonation properties of 3, 4, and 6 were predicted. Their enthalpy of formation (ΔHf), detonation velocities (D), and detonation pressures (P) were in the ranges of 110.1 kJ mol−1 to 349.9 Kj mol−1, 7264 m s−1 to 7770 m s−1, and 21.8 GPa to 25.9 GPa, respectively. Notably, the density, thermal decomposition temperature, detonation velocity, detonation pressure, and impact sensitivity value of compound 3 were 1.76 g cm−3, 313°C, 7546 m s−1, 24.2 GPa, and 16 J, respectively, suggesting that compound 3 is a high‐performance heat‐resistant explosive.

Temperature Changes in Luminescence of Mixed Complexes of Terbium and Samarium with Organic Ligands Based on 2,2-bipyridyldicarboxamides

Solutions in acetonitrile of three mixed complexes of rare earth elements (terbium and samarium) with organic ligands with various pyridine substituents were studied in this work. The ratios of ligands and metals in the resulting complexes were determined, and the stability constants of samarium complexes were calculated using the spectrophotometric titration method. Measurements of absorption, emission and excitation spectra of luminescence, luminescence kinetics of solutions of mixed complexes of rare earth elements with an excess of metal relative to the ligand were carried out at various temperatures in the range 298–328 K. An increase of luminescence intensity of a samarium ion in complex upon heating has been discovered for the first time. The dependences of the luminescence quantum yield and lifetime of mixed complexes on temperature were obtained. A thermometric parameter — the ratio of the integral luminescence intensities of samarium and terbium ions — was proposed, and the temperature sensitivity coefficient of this parameter was determined for different complexes.