Temperature Dependence Research Articles

Rotating SU(2) gluon matter and deconfinement at finite temperature

In this work a non-abelian gauge theory is reformulated in a rotating frame. With this new formalism, the influence of the background rotation on the color deconfinement transition for a pure SU(2) gluon system has been studied. The KvBLL caloron, which is a color neutral and topologically nontrivial solution of Yang-Mills equation at finite temperature, is reexamined under rotation and adopted as the confined vacuum of such a system. With rotation-modified solutions of the caloron's constituent solitons, i.e. dyons, the non-perturbative part of effective potential of the rotating system has been obtained. Combining with the perturbative potential by Gaussian fluctuations, the critical temperature of confinement-deconfinement phase transition is investigated. It is found that neither the rotational semi-classical potential nor Gaussian fluctuations can confine color charges more tightly when the rotation becomes faster. While only a stronger coupling constant is able to make the critical temperature increase with angular velocity, as what indicated in lattice simulations. And it is found a non-monotonic dependence of the critical temperature on the angular velocity is established because of the competition between these two contrary contributions.

A finite crack growth energy release rate for interlaminar fracture analysis of composite material at different temperatures

The interlaminar fracture toughness of unidirectional fiber reinforced polymer composite material is temperature and crack growth history dependence. The non-constant interlaminar fracture toughness challenges the wide application of the linear elastic fracture mechanics-based approach for analyzing the interlaminar crack growth in composite material and structures. In addition, a quantitative relationship between the ductility of the matrix and interlaminar fracture toughness of the fiber reinforced composite is still highly desirable. In this paper, both pure resin and composite double cantilever beam (DCB) are tested at different temperatures. A finite crack growth energy release rate is used to analyze the interlaminar crack growth behavior of composite material at different temperatures. The plasticity of the composite DCB is modeled by Hill’s anisotropic plasticity, with the properties determined from multiscale analyses. It is found that a single constant finite growth energy release rate can well predict the interlaminar mode I crack growth of composite material at different temperatures. The roles of the ductility of matrix, thickness of the DCB, and crack growth history on the interlaminar mode I fracture toughness of composite material are quantitatively determined by using the present method.

27 MHz constant field dielectric warming of kidneys cryopreserved by vitrification

Organs cryopreserved by vitrification are exposed to the lowest possible concentration of cryoprotectants for the least time necessary to successfully avoid ice formation. Faster cooling and warming rates enable lower concentrations and perfusion times, reducing toxicity. Since warming rates necessary to avoid ice formation during recovery from vitrification are typically faster than cooling rates necessary for vitrification, warming speed is a major determining factor for successful vitrification. Dielectric warming uses an oscillating electric field to directly heat water and cryoprotectant molecules inside organs to achieve warming that's faster and more uniform than can be achieved by heat conduction from the organ surface. This work studied 27 MHz dielectric warming of rabbit kidneys perfused with M22 vitrification solution. The 27 MHz frequency was chosen because its long wavelength and penetration depth are suitable for human organs, because it had an anticipated favorable temperature of maximum dielectric absorption in M22, and because it's an allocated frequency for industrial and amateur use with inexpensive amplifiers available. Previously vitrified kidneys were warmed from −100 °C by placement in a 27 MHz electric field formed between parallel capacitor plates in a resonant circuit. Power was varied during warming to maintain constant electric field amplitude between the plates. Maximum power absorption occurred near −70 °C, with a peak warming rate near 150 °C/min in 50 mL total volume with approximately 500 W power. After some optimization, it was possible to warm ∼13 g vitrified kidneys with unprecedentedly little injury from medullary ice formation and a favorable serum creatinine trend after transplant. Distinct behaviors of power absorption and system tuning observed as a function of temperature during warming are promising for non-invasive thermometry and future automated control of the warming process at even faster rates with user-defined temperature dependence.

Crystal structure and thermodynamic properties of the new compound Sc4Sb2.52 in the Sc-Sb system

The new compound Sc4Sb2.52 was first discovered, which was synthesized by the arc-melting under high purity argon. The composition of the new compound was examined by energy dispersive X-ray spectroscopy (EDS). Its crystal structure was first determined using X-ray powder diffraction data by Rietveld method. In order to further verify its structure, it was also observed by transmission electron microscope (TEM). The compound crystallized in a cubic Th3P4-type structure with the space group I4¯3d (No. 220) and the lattice parameter is a = 8.65454(9) Å. Its atomic positions are Sc at 16c (0.0736(3), 0.0736(3), 0.0736(3)), and Sb at 12a (0.375, 0, 0.25). The heat capacity (Cp) of the new compound Sc4Sb2.52 was reported for the first time, which were measured using differential scanning calorimetry (DSC) in a temperature range from 105 K to 450 K. The curve of Cp shows the normal sigmoidal temperature dependence with no evidence of transitions and other anomalies, and which was fitted using Debye function from 0 K to 77 K and using Maier-Kelley type expression from 77 K to 450 K. The entropy, enthalpy and free-energy values were derived with integration of the heat capacities based on the relations of thermodynamic properties with Cp.

Damage recovery stages revisited: Thermal evolution of non-saturated and saturated displacement damage in heavy-ion irradiated tungsten

Establishing the correlation between damage recovery and temperature in nuclear materials is vital to understanding material property degradation. Among the handful of topics related, one long-standing concern is the differences in damage recovery caused by different initial defect concentrations, with respect to ranges below and beyond the damage saturation limit. In this study, the temperature dependence of damage recovery has been comprehensively elucidated for pure tungsten, irradiated with 6 MeV copper ions at room temperature (RT), up to 0.05 dpa (non-saturated damage, n-SD) and 0.6 dpa (saturated damage, SD), and followed by isochronal annealing. Coupled transmission electron microscopy and Doppler broadening positron annihilation spectroscopy characterizations provided a full-probe-range picture of defect evolution. The varied initial defect concentrations caused retaining differences in damage recovery, but no substantial influence on temperature-dependent defect evolution. Moderate and dramatic damage recovery were identified below 973 K and above 1123 K in n-SD and SD tungsten, respectively. Most strikingly, nano-sized voids were confirmed at 473 K in both samples. Annealing at 1873 K saw the complete removal of defects in n-SD tungsten, but survival of a few dislocations via void pinning in SD tungsten. Full damage recovery in SD tungsten was projected to be ∼2000 K. The current revisit of damage recovery stages demonstrated the significance of encompassing scenarios of non-saturated and saturated defect concentrations. Accordingly, four damage recovery stages were redefined for heavy-ion irradiated tungsten, namely stage I (20 K–RT), stage II (RT–653 K), stage III (653–1123 K), and stage IV (1123–2000 K).

Anomalous Current Steps in 3D Graphene Electrochemical Systems at Room Temperature.

In this work, we report a new phenomenon in electrochemical systems whereby uniform current steps of 1 mA per 0.5 × 0.5 × 0.1 cm3 (width × width × depth) of electrode volume occurred during the electrodeposition of gold and silver nanoparticles onto 3D microporous graphene on nickel layers (GF/Ni) at room temperature. The effect was exhibited only at specific applied electrical potentials. The experiments (magnetic interference, temperature dependence, and surface area dependence) were repeated, and the results were reproducible. Finally, we proposed classical electrochemical theory using the Butler-Volmer equation and quantum theory using the Landauer formalism to describe this new effect. Both theories could be used to explain the experimental results: temperature dependence, surface area dependence, blocking effects, and external magnetic field dependence. In addition, the stepwise current presented in this work facilitates the trapping and supplying of a large amount of electric charge via an inherent magnetic field in a sharp time step (∼1 s). A video clip of the recorded effect can be found at https://youtu.be/pPJh45w1sUQ.

Thermometric Analysis of Nanoaperture-Trapped Erbium-Containing Nanocrystals.

Temperature changes in plasmonic traps can affect biomolecules and quantum emitters; therefore, several works have sought out the capability of measuring the local temperature. Those works used ionic nanopore currents, fluorescence emission variations, and fluorescence-based diffusion tracking to measure the temperature dependence of shaped nanoapertures in metal films. Here, we make use of a stable erbium-containing NaYF4 nanocrystal that gives local temperature dependence while trapped in the nanoaperture hot spot. Ratiometric analysis of the emission at different wavelengths gives local temperature variation. Since the gold film dominates the thermal characteristic, we find that films of thickness 70, 100, and 130 nm give 0.64, 0.37, and 0.25 K/mW temperature change with laser power. Therefore, using thicker films can be effective in reducing the heating when it is not desired.

Current and future cosmological impact of microwave background temperature measurements

The redshift dependence of the cosmic microwave background temperature, T(z)=T0(1+z), is a key prediction of standard cosmology, but this relation is violated in many extensions thereof. Current astrophysical facilities can probe it in the redshift range 0≤z≤6.34. We extend recent work by Gelo et al. (2022) showing that for several classes of models (all of which aim to provide alternative mechanisms for the recent acceleration of the universe) the constraining power of these measurements is comparable to that of other background cosmology probes. Specifically, we discuss constraints on two classes of models not considered in the earlier work: a model with torsion and a recently proposed phenomenological dynamical dark energy model which can be thought of as a varying speed of light model. Moreover, for both these models and also for those in the earlier work, we discuss how current constraints may be improved by next-generation ground and space astrophysical facilities. Overall, we conclude that these measurements have a significant cosmological impact, mainly because they often constrain combinations of model parameters that are orthogonal, in the relevant parameter space, to those of other probes.

Single-particle spectroscopies of p-wave and d-wave interacting Bose gases in normal phase

Motivated by experiments with interacting quantum gases across high partial wave resonance, we investigate the thermodynamic properties and single-particle spectra of Bose gases in normal phase for different interaction strengths for both p- and d-wave interactions. The equation of state, contact density, momentum distributions and self-energies of single-particle Green’s functions are obtained in the spirit of ladder diagram approximations. The radio-frequency (RF) spectrum, as an important experimental approach for detecting Feshbach molecules or the interaction effect, is calculated at different temperatures. A reversed temperature dependence on the Bose–Einstein condensation side and Bardeen–Cooper–Schrieffer side is identified for both p- and d-wave interactions. An estimate for the signal of RF spectra under typical experimental conditions is also provided.

Bmal1 integrates circadian function and temperature sensing in the suprachiasmatic nucleus

Circadian regulation and temperature dependency are important orchestrators of molecular pathways. How the integration between these two drivers is achieved, is not understood. We monitored circadian- and temperature-dependent effects on transcription dynamics of cold-response protein RNA Binding Motif 3 (Rbm3). Temperature changes in the mammalian master circadian pacemaker, the suprachiasmatic nucleus (SCN), induced Rbm3 transcription and regulated its circadian periodicity, whereas the core clock gene Per2 was unaffected. Rbm3 induction depended on a full Brain And Muscle ARNT-Like Protein 1 (Bmal1) complement: reduced Bmal1 erased Rbm3 responses and weakened SCN circuit resilience to temperature changes. By focusing on circadian and temperature dependency, we highlight weakened transmission between core clock and downstream pathways as a potential route for reduced circadian resilience.

Sequence-dependent dipeptide solubility in ethanol-water and DMSO-water solutions

Reliable solubility data is crucial for controlling and optimising crystallisation conditions, to provide a cost-effective purification method with the potential for scaling up. This study investigated the effect of amino acid sequence on determining peptides solubility behaviours. Four dipeptides with different sequences and combinations of alanine and glycine were selected to study their temperature dependent (283.15 K to 313.15 K) aqueous solubilities and solubility in the presence of ethanol and DMSO as antisolvent at 298.15 K. Aqueous solubility data of dipeptides presents the following order: glycyl-L-alanine (gly-ala) > L-alanyl-L-alanine (ala-ala) > glycyl glycine (gly-gly) > L-alanyl glycine (ala-gly). This solubility order has been substantiated by solvation free energy calculations using molecular dynamics (MD) simulations, providing insights into the underlying molecular interactions that govern these solubility patterns. The solubility data also demonstrated difference in the temperature dependency that: gly-gly > gly-ala > ala-gly > ala-ala, corresponding to their dissolution enthalpy order. In the presence of antisolvent range from 0 % to 80 % (by mass) concentration, peptide’s solubility was more susceptible to DMSO than ethanol. Accurate prediction of the solubilities validated the effectiveness of non-random two-liquid (NRTL) model for peptide studies.

Mid- and High-Latitude Electron Temperature Dependence on Solar Activity in the Topside Ionosphere through the Swarm B Satellite Observations and the International Reference Ionosphere Model

This study focuses on the open question of the electron temperature (Te) variation with solar activity in the topside ionosphere at mid- and high latitudes. It takes advantage of in situ observations taken over a decade (2014–2023) from Langmuir probes on board the low-Earth-orbit Swarm B satellite and spanning an altitude range of 500–530 km. The study also includes a comparison with Te values modeled using the International Reference Ionosphere (IRI) model and with Millstone Hill (42.6° N. 71.5° W) incoherent scatter radar observations. The largest Te variation with solar activity was found at high latitudes in the winter season, where Te shows a marked decreasing trend with solar activity in the polar cusp and auroral regions and, more importantly, at sub-auroral latitudes in the nightside sector. Differently, in the summer season, Te increases with solar activity in the polar cusp and auroral regions, while for equinoxes, variations are smaller and less clear. Mid-latitudes generally show negligible Te variations with solar activity, which are mostly within the natural dispersion of Te observations. The comparison between measured and modeled values highlighted that future implementations of the IRI model would benefit from an improved description of the Te dependence on solar activity, especially at high latitudes.

Experimental study of rotational relaxation for D2(1,12) in collisions with N2.

The rotational relaxation behavior of D2(1,12) in a D2-N2 mixture was investigated using coherent anti-Stokes Raman scattering (CARS) technique. The rovibrational level v = 1 and J = 12 of D2 was selectively excited through stimulated Raman pumping while monitoring the temporal evolution of population for D2(1, J ≤ 12) molecules using time-resolved CARS spectroscopy. The results demonstrate that the rotational relaxation processes of D2(1,12) encompass both multi-quantum relaxation and continuous single-quantum relaxation. When α, the molar ratio of N2, is less than 0.5, D2(1,12) predominantly undergoes a single quantum relaxation process transition. However, when α ≥ 0.5, the multi-quantum relaxation mechanism gradually predominates. The total rotational relaxation rate coefficients of D2(1,12) collisions with N2 and D2 at 295K were determined to be 3.974 × 10-14 and 1.179 × 10-14cm3s-1, respectively. The temperature dependence of rotational relaxation rate of D2(1,12) was investigated within the temperature range of 295-453K. With increasing temperature, the dominant relaxation process exhibited an accelerated behavior, while the minor relaxation process remained largely unaffected. The rotational temperature of the D2molecule at various N2 molar ratios was determined through the utilization of Boltzmann plots. The rotational temperature undergoes a rapid decline within 2 μs, corresponding to the near-resonant rotation-vibration relaxation process of D2(1,12) collisions with N2. The system reaches a quasi-equilibrium state when the delay time is 3 μs. The findings of this study can serve as a valuable empirical basis for further validation of the kinetic theory and simulation.

On the Impact of Bimolecular Recombination on Time‐Delayed Collection Field Measurements and How to Minimize Its Effect

The time‐delayed collection field (TDCF) technique is a popular method to quantify the field and temperature dependences of free charge generation in organic solar cells. Because the method relies on the extraction of photogenerated charge carriers, bimolecular recombination not only between the photogenerated carriers but also between the photogenerated and dark‐injected carriers affects its accuracy, particularly at forward bias. In this work, drift–diffusion simulations are employed to quantify the recombination losses in conventional and modified TDCF measurements, where the latter technique intends to reduce the impact of dark injection. It is shown that parameters such as the generation profile, carrier mobilities, and effective density of states affect the recombination losses in both measurements. Importantly, modified TDCF enables to reduce the recombination losses at forward bias, especially beyond the open‐circuit voltage. However, conventional TDCF is preferable for studies at reverse bias due to a better depletion of the active layer prior to the emergence of the photogenerated carriers. Measurements on a ZR1:Y6 blend with fast recombination are in good agreement with the simulation results. This work shows that artifacts in TDCF measurements related to non‐geminate recombination can be accounted for and minimized through an informed choice of the experimental conditions.

High-temperature strength and kink-band formation in mille-feuille-structured Ti/FeTi eutectic alloys

To develop ultrahigh-strength and lightweight structural materials, the temperature dependence of the deformation behavior of Ti/FeTi eutectic alloys was examined using compression tests. An extremely high yield stress of ∼2.3 GPa was obtained at room temperature accompanied by ∼5 % of plastic strain by the alignment of a “flower-like” lamellar microstructure. High stress was maintained up to 400 °C; however, the yield stress considerably decreased to ∼0.8 GPa at 600 °C. Shear deformation was observed at room temperature. However, at high temperatures, at 600 °C and above, the formation of a deformation kink band was observed for the first time as the deformation mechanism, and this resulted in a rapid decrease in yield stress. The size of the kink bands was governed by the diameter of the aligned lamellar grains, which was termed the colony size. Large kink bands were formed in the alloy containing coarse colonies, resulting in the buckling of the specimen. The introduction of primary β-Ti grains in the eutectic microstructure improved the ductility at low temperatures, which was only accompanied by the marginal decrease in yield stress to ∼1.9 GPa. Furthermore, the high-temperature strength of the hypoeutectic alloy at 600 °C showed a higher value of ∼1.0 GPa compared to that in eutectic alloys. The refinement of the colony microstructure of the hypoeutectic alloy suppressed the formation of kink bands. The experimental results suggest that microstructural control is extremely important for improving the high-temperature strength of Ti/FeTi eutectic alloys by increasing the formation stress of the kink bands.

Pressure and temperature dependent ab-initio quasi-harmonic thermoelastic properties of tungsten

We present the ab-initio temperature and pressure dependent thermoelastic properties of body-centered cubic tungsten. The temperature dependent quasi-harmonic elastic constants (ECs) are computed at several reference volumes including both the phonon and the electronic excitations contribution to the free energy and interpolated at different temperatures and pressures. Good agreement with the experimental ECs on a single crystal at ambient pressure is found. The pressure and temperature dependence of the shear sound velocity measured on polycrystalline tungsten by Qi et al is also in agreement with theory. Some discrepancies are found instead for the compressional velocity at high temperature and this is attributed to the temperature derivative of the bulk modulus, higher in theory than in experiment. These conclusions are reached both by PBE and by PBEsol functionals. The two give elastic properties with a similar pressure and temperature dependence although the latter is closer to experiment at 0 K.

Ultralow Glassy Thermal Conductivity and Controllable, Promising Thermoelectric Properties in Crystalline o-CsCu5S3.

We thoroughly investigated the anharmonic lattice dynamics and microscopic mechanisms of the thermal and electronic transport characteristics in orthorhombic o-CsCu5S3 at the atomic level. Taking into account the phonon energy shifts and the wave-like tunneling phonon channel, we predict an ultralow κL of 0.42 w/mK at 300 K with an extremely weak temperature dependence following ∼T-0.33. These findings agree well with experimental values along with the parallel to the Bridgman growth direction. The κL in o-CsCu5S3 is suppressed down to the amorphous limit, primarily due to the unconventional Cu-S bonding induced by the p-d hybridization antibonding state coupled with the stochastic oscillation of Cs atoms. The nonstandard temperature dependence of κL can be traced back to the critical or dominant role of wave-like tunneling of phonon contributions in thermal transport. Moreover, the p-d hybridization of Cu(3)-S bonding results in the formation of a valence band with "pudding-mold" and high-degeneracy valleys, ensuring highly efficient electron transport characteristics. By properly adjusting the carrier concentration, excellent thermoelectric performance is achieved with a maximum thermoelectric conversion efficiency of 18.4% observed at 800 K in p-type o-CsCu5S3. Our work not only elucidates the anomalous electronic and thermal transport behavior in the copper-based chalcogenide o-CsCu5S3 but also provides insights for manipulating its thermal and electronic properties for potential thermoelectric applications.

What Can we Learn from Nonequilibrium Response of a Strange Metal?

We critically address the recent experiment by L. Chen et al. [Science 382, 907 (2023)] on nonequilibrium transport and noise in a strange metal YbRh2Si2 patterned into the nanowire shape. In the long device, resistivity, differential resistance and current noise data seem to be consistent allowing us to extract electron-phonon coupling and the temperature dependence of electron-phonon scattering length. The obtained values can be reconciled with the experimental data for the short device only assuming the significant contact resistance. We discuss its possible origin as due to the current redistribution between YbRh2Si2 and its gold covering, and reveal that this redistribution contact resistance should be proportional to the YbRh2Si2 resistivity. We also discuss some subtleties of the noise measurements. Overall, neglecting electron-phonon energy relaxation even in the shortest devices is arguable so that the observed shot noise suppression can hardly be attributed to the failure of quasiparticle concept.

Faraday isolator with compensation depolarization caused by Verdet constant temperature dependence

Faraday isolator with compensation depolarization caused by Verdet constant temperature dependence

A modification to the Friedman and Ortega isoconversional methods for evaluation of the activation energy as a function of conversion and temperature

The Friedman and Ortega isoconversional methods typically apply linear regression to the isoconversional kinetic data for calculation of activation energy solely as a function of extent of conversion. However, in complex reactions, activation energy depends on both conversion and temperature. Our modification involves quadratic curve fitting instead of linear regression, resulting in the determination of activation energy as a function of conversion and temperature. The new technique enables the calculation of the temperature dependence of activation energy for different heating rates, making it a valuable addition to isoconversional analysis. The conventional and modified approaches were utilized on the isoconversional kinetic data concerning polyethylene thermal degradation. The results provided a more detailed representation of the variations in activation energy when nonlinear regression was used.