High Temperature Regime Research Articles

Motion of Leidenfrost self-propelled droplets on ratchet in low- and high-temperature regimes

Motion of Leidenfrost self-propelled droplets on ratchet in low- and high-temperature regimes

Integrated geophysical-petrological model of Damavand volcano, North Iran: Compositional structure of crust and upper mantle from seismic temperature profiling and gravity anomaly fitting

Our study employs well-constrained integrated geophysical-petrological modeling to investigate the compositional structure of Damavand volcano, the Alborz mountains in northern Iran. The thermochemical model utilizes high-resolution compressional velocity anomalies to determine temperature, while geochemical data from volcanic rocks further constrain mostly the lithospheric mantle model. By examining density and velocity, we deduce the upper mantle's compositional structure using observed free-air gravity anomalies and shear-wave seismic models. Our results reveal a lower crust density reduction of 150 kg/m3 due to a high-temperature regime (1080 °C) and the presence of melt indicated by a calculated Vp/Vs ≥ 1.8. The magma storage in the lithosphere is characterized by a harzburgite-melt mixture in agreement with shear-wave seismic profiles, and the lithospheric magma reservoir is positively buoyant with a density reduction of ∼75 kg/m3 compared to the ambient lithospheric mantle. The absence of a warm zone beneath the Alborz suggests that a transient mantle flow from the 660 km transition zone beneath Eurasia is responsible for the lateral heating (and possibly hydration) of the lithospheric mantle. This aligns with the high-temperature conditions observed in the Damavand (Alborz) region. Furthermore, the presence of elevated Nb (and high Nb/Yb ratio as well as radiogenic Nd isotope) concentrations in certain volcanic rocks suggests that a portion of the melt may have originated from the Earth's asthenosphere mantle. Moreover, the existence of water and/or volatiles (likely ≥0.64 wt%, as determined through a comparison of predicted and observed seismic velocities, along with previous laboratory analyses) promotes decompression melting of the lithospheric mantle at significantly lower temperatures (1230–1130 °C) in contrast to earlier estimations (1430–1180 °C). Finally, the reductions in velocity observed in the lower crust and uppermost lithospheric mantle beneath Damavand are likely attributed to thermal and compositional factors, respectively. The presence of a hydrated and melt-rich composition within the lithospheric mantle can account for the observed decrease in seismic velocity.

Carrier transport across PtSe2/n-type GaN heterojunction

We fabricated PtSe2/n-type GaN heterojunction diode by transferring a large-scale grown two-dimensional (2D) PtSe2 layered film onto a 3D GaN substrate. The PtSe2 film transferred onto GaN was ∼5.84-nm thick and had 11 layers with interlayer spacing of 0.52 nm. An exploration of the temperature-dependence of the current–voltage (I–V) characteristics of the PtSe2/n-type GaN heterojunction in the range 125–400 K revealed a strong dependency of the ideality factor and barrier height on measurement temperature. This indicates a presence of low- and high-barrier-height patches resembling barrier inhomogeneities along the interface. A barrier inhomogeneity analysis with a consideration for the Gaussian barrier heights distribution demonstrated the existence of a double Gaussian barrier distribution having a mean barrier height of 0.97 and 1.41 eV in low- and high-temperature regimes, respectively. An examination of the temperature-dependency of reverse leakage current indicated the dominance of variable-range hopping conduction in lower temperature region (<225 K) and Poole–Frenkel emission mechanism in higher temperature region (>250 K). The interface state density Nss of the PtSe2/n-type GaN heterojunction determined from the capacitance method was lesser than that attained from the forward I–V characteristics that can be accredited to the inhomogeneous spreading of the Nss.

Exact Quantum Virial Expansion for the Optical Response of Doped Two-Dimensional Semiconductors.

We introduce a quantum virial expansion for the optical response of a doped two-dimensional semiconductor. As we show, this constitutes a perturbatively exact theory in the high-temperature or low-doping regime, where the electrons' thermal wavelength is smaller than their interparticle spacing. We obtain exact analytic expressions for the photoluminescence and we predict new features such as a nontrivial shape of the attractive branch peak related to universal resonant exciton-electron scattering and an associated energy shift from the trion energy. Our theory furthermore allows us to formally unify the two distinct theoretical pictures that have been applied to this system, where we reveal that the predictions of the conventional trion picture correspond to a high-temperature and weak-interaction limit of Fermi-polaron theory. Our results are in excellent agreement with recent experiments on doped monolayer MoSe_{2} and they provide the foundation for modeling a range of emerging optically active materials such as van der Waals heterostructures.

QCD mesonic screening masses using Gribov quantization

The screening masses of mesons provide a gauge invariant and definite order parameter of chiral symmetry restoration. Different mesonic correlation lengths for flavor non-singlets, at least up to NLO, are well-defined gauge invariant physical quantities calculated earlier using the perturbative resummation techniques. The NLO perturbative results match the available non-perturbative lattice QCD results at the high-temperature regime. We have studied the spatial correlation lengths of various mesonic observables using the non-perturbative Gribov resummation, both for quenched QCD and (2+1) flavor QCD. The study follows the analogies with the NRQCD effective theory, a well-known theory for studying heavy quarkonia at zero temperature.

Laminar flame speed measurements of ethanol, iso-octane, and their binary blends at temperatures up to 1020 K behind reflected shock waves

A shock tube augmented with a laser-spark ignition system was used to measure the atmospheric-pressure (1 atm ±2%) laminar flame speeds of neat ethanol and iso-octane as well as ethanol/iso-octane blends in a 21% O2-79% Ar (so-called “airgon”) oxidizer. Low-temperature (453 K–524 K) validation experiments of atmospheric-pressure, stoichiometric ethanol/air were first performed for comparison with literature. Two fuel blends with 50% and 85% ethanol (by volume) in iso-octane (E50 and E85, respectively) were then studied in airgon at high unburned-gas temperatures (637 K–1020 K) and at various equivalence ratios (0.75, 1, and 1.2). The low-temperature ethanol/air measurements showed good agreement with literature data, confirming the accuracy of flame speeds measured using a shock tube. High-temperature fuel/airgon flame speeds were simulated with various kinetic models, and significant model disagreement was found, highlighting the value of the new flame speed data in the high-temperature regime. To make the present fuel/airgon measurements compatible with practical engineering applications using air as the oxidizer, the ratio of fuel/airgon and fuel/air flame speeds was calculated using 1D simulations for each experiment, then subsequently used to perform mixture-scaling for the fuel/airgon data to obtain equivalent fuel/air flame speeds. Fuel/air laminar flame speed correlations as a function of the unburned-gas temperature were determined for the studied fuel blends and equivalence ratios. Finally, flame speed sensitivity analyses conducted for high-temperature ethanol/airgon and iso-octane/airgon flames revealed three key governing reactions. Assigning common rate expressions to these reactions across different kinetic models improved the agreement between model-predicted and experimentally measured ethanol flame speeds, but did not have a similar effect for iso-octane, suggesting the need for further exploration of iso-octane-specific reaction rates to facilitate better model agreement.

The relationship between the degree of violation of Bell-CHSH inequality and measurement uncertainty in two classes of spin squeezing mechanisms

In solid-state systems, spin squeezing states have acquired much interest in quantum information processing since they are not only essential from a basic physics standpoint but also have many applications, notably reducing noise in interferometry. This paper addresses the study of quantum nonlocality as examined by the violation of the Bell and Clauser–Horne–Shimony–Holt (CHSH) inequality in two classes of spin squeezing states and how this relates to the quantum-memory-assisted entropic uncertainty relation (QMA–EUR). The spin squeezing states in the two classes are systematically generated by two twisting nonlinear interactions. These separately describe two spin-[Formula: see text] interaction mechanisms that undergo one-axis twisting (OAT) and two-axis countertwisting (TAC). We investigate each spin squeezing mechanism in a thermal bath ([Formula: see text]) with a transverse magnetic field. Our main results indicate that the degree of violation of the Bell-CHSH inequality and the entropic uncertainty relation (EUR) is typically anticorrelated in both mechanisms. We demonstrate that the spin squeezing states in the OAT mechanism violate the Bell-CHSH inequality and thus exhibit Bell nonlocality only at low temperatures ([Formula: see text]), whereas in the TAC mechanism, increasing the strength of the spin squeezing interaction leads to a violation of the Bell-CHSH inequality even at finite temperatures. We have also shown that there is always an expansion of the EUR and a decrease in the degree of violation of the Bell-CHSH inequality in the high-temperature regime. In addition, the transverse magnetic field exhibits different behavior under the considered temperature regimes in the two classes of spin squeezing states. Other results will also be discussed.

Derivation of Anomalous Behavior from Interacting Oscillators in the High-Temperature Regime

AbstractA microscopic model of interacting oscillators, which admits two conserved quantities, volume, and energy, is investigated. We begin with a system driven by a general nonlinear potential under high-temperature regime by taking the inverse temperature of the system asymptotically small. As a consequence, one can extract a principal part (by a simple Taylor expansion argument), which is driven by the harmonic potential, and we show that previous results for the harmonic chain are covered with generality. We consider two fluctuation fields, which are defined as a linear combination of the fluctuation fields of the two conserved quantities, volume, and energy, and we show that the fluctuations of one field converge to a solution of an additive stochastic heat equation, which corresponds to the Ornstein–Uhlenbeck process, in a weak asymmetric regime, or to a solution of the stochastic Burgers equation, in a stronger asymmetric regime. On the other hand, the fluctuations of the other field cross from an additive stochastic heat equation to a fractional diffusion equation given by a skewed Lévy process.

Ignition delay times of C1–C7 natural gas blends in the intermediate and high temperature regimes: Experiment and correlation

This study presents new ignition delay time data for two multi-component natural gas (NG) blends composed of C1–C7n-alkanes with methane as the major component. New experimental data were recorded using a high-pressure shock tube (HPST) at reflected shock pressures (p5) of 10–30 bar, at temperatures (T5) in the range 770–1480 K, and at equivalence ratios (φ) of 0.5–1.5 in ‘air’. The current results together with published rapid compression machine (RCM) measurements show that higher concentrations of larger molecular weight n-alkanes in the NG blends increase fuel reactivity by more than an order of magnitude with mixtures that have ∼18.75% of C3–C5 components compared to mixtures that have ∼44.4% of C3–C7 components at temperatures below 1000 K. On the contrary, at higher temperatures the effect of increasing reactivity is reduced. NUIGMech1.2 is used to simulate the conditions studied and shows good agreement with the experimental ignition delay time data. A correlation equation is developed through regression analyses using NUIGMech1.2 to predict ignition delay times for a wide range of C1–C7 NG mixtures, in the pressure range 10–50 bar, at temperatures in the range 950–2000 K, and at φ = 0.3–3.0 in air. The proposed correlation expression that employs a traditional Arrhenius form is successfully validated against the new experimental data as well as previously published HPST experimental data.

Temperature-Dependent Contact of Weakly Interacting Single-Component Fermi Gases and Loss Rate of Degenerate Polar Molecules.

Motivated by the experimental realization of single-component degenerate Fermi gases of polar ground state KRb molecules with intrinsic two-body losses [L. De Marco et al., A degenerate Fermi gas of polar molecules, Science 363, 853 (2019).SCIEAS0036-807510.1126/science.aau7230], this work studies the finite-temperature loss rate of single-component Fermi gases with weak interactions. First, we establish a relationship between the two-body loss rate and the p-wave contact. Second, we evaluate the contact of the homogeneous system in the low-temperature regime using p-wave Fermi liquid theory and in the high-temperature regime using the second-order virial expansion. Third, conjecturing that there are no phase transitions between the two temperature regimes, we smoothly interpolate the results to intermediate temperatures. It is found that the contact is constant at temperatures close to zero and increases first quadratically with increasing temperature and finally-in agreement with the Bethe-Wigner threshold law-linearly at high temperatures. Fourth, applying the local-density approximation, we obtain the loss-rate coefficient for the harmonically trapped system, reproducing the experimental KRb loss measurements within a unified theoretical framework over a wide temperature regime without fitting parameters. Our results for the contact are not only applicable to molecular p-wave gases but also to atomic single-component Fermi gases, such as ^{40}K and ^{6}Li.

Entropy of causal diamond ensembles

We define a canonical ensemble for a gravitational causal diamond by introducing an artificial York boundary inside the diamond with a fixed induced metric and temperature, and evaluate the partition function using a saddle point approximation. For Einstein gravity with zero cosmological constant there is no exact saddle with a horizon, however the portion of the Euclidean diamond enclosed by the boundary arises as an approximate saddle in the high-temperature regime, in which the saddle horizon approaches the boundary. This high-temperature partition function provides a statistical interpretation of the recent calculation of Banks, Draper and Farkas, in which the entropy of causal diamonds is recovered from a boundary term in the on-shell Euclidean action. In contrast, with a positive cosmological constant, as well as in Jackiw-Teitelboim gravity with or without a cosmological constant, an exact saddle exists with a finite boundary temperature, but in these cases the causal diamond is determined by the saddle rather than being selected a priori.

Polyphase deformation of staurolite-bearing metapelite in the Chinese Altai: Recording a Devonian-Permian tectonic regime switch in the southwestern Central Asian Orogenic Belt

Recent studies revealed that the Chinese Altai may have experienced two major tectonothermal events in the Devonian and Permian but their mutual relationships remain poorly constrained. In this study, we carried out a comprehensive analysis of macro- and micro-structural features of the Ordovician schists that were subjected to Barrovian-type metamorphism in the Chonghuer area of the northwestern Chinese Altai. Field structural and microstructural analyses revealed that metamorphic foliation S1 was folded by the recumbent fold F2, forming the sub-horizontal foliation S2. The S2 fabric was later reworked by the D3 transpressional shearing along the narrow sillimanite-bearing zone to form the foliation S3. Monazite U–Pb ages obtained from the staurolite schist located close to the D3 shear zone, as well as the zircon U–Pb ages from both folded and unfolded pegmatites that cross-cut granite, indicate that the D3 deformation took place during the Permian period, approximately 257–250 Ma. The EBSD study of quartz in the matrix and staurolite porphyroblasts conducted along the NE-SW cross-section allowed us to: 1) constrain the medium-temperature D2 and high-temperature D3 regimes and, 2) reconstruct foliation intersection axis (FIA) patterns both inside and outside the D3 deformation zone. The FIA between Devonian D1 and D2 preserved in staurolite porphyroblast was initially oriented in a N–S direction, which was ultimately reoriented to a NW-SE direction after undergoing the D3 shear deformation. This result is further reinforced by the numerical stochastic modelling, which quantifies the influence of the Permian HT sinistral transpression on the reworking of the Devonian FIA fabrics. Micro-structural data of this study verifies the significant tectonic switch from the Devonian E-W contraction to the Permian NNW-SSE transpression. Quantitative EBSD-based FIA analysis proves to be an effective approach for the structural analysis of polycyclic orogenic systems.

Deposition of graphenic nanomaterials from elevated temperature premixed stagnation flames

The work examines the unique nanostructure of carbon nanoparticles deposited from sooting premixed flames with flame temperatures exceeding 2200 K. This flame temperature regime has previously been shown to transition from typical soot formation conditions to a regime whereby the flame-form carbon adopts a nanostructure considerably more ordered than soot. Graphenic carbon deposits observed by High-resolution TEM (HRTEM) are reported here corroborating previous Raman spectroscopy evidence. The use of premixed stretch-stabilized flames enables particle production in the high-temperature regime under a flow field amenable to low-dimensional flame modeling. Although the flame flow configuration is relatively simple, three sample preparation methods are used to assess the representation of true carbon properties as they exist in the flame. HRTEM imaging is carried out on carbon particle samples prepared by rapid-insertion deposition, aerosol dilution probe deposition and carbon particle film deposition. Images from rapid-insertion samples show amorphous particles in the lightly sooting flame and turbostratic particles in the heavy sooting flame. There is trace evidence of graphenic structure in rapid-insertion samples but the most striking particles on the TEM grid are graphite nanocrystals presumably formed by a new artificial crystallization process. HRTEM images of particles collected over time by diluted aerosol deposition and film deposition show clear graphenic structures. Overall, the carbon nanostructure observed by HRTEM is a mixture of amorphous, turbostratic and graphenic carbon lattices depending on the flame condition and sampling method. The current work highlights potential impacts of higher flame temperatures and higher equivalence ratio on deposited flame-formed carbon. Namely, graphenic particle structure is observed in rapid-insertion deposition samples but graphene portions are most abundant in aerosol dilution and carbon particle film deposition samples. This may indicate that graphene structures grow on the deposition surface over time.

A proposal for 3d quantum gravity and its bulk factorization

Recent progress in AdS/CFT has provided a good understanding of how the bulk spacetime is encoded in the entanglement structure of the boundary CFT. However, little is known about how spacetime emerges directly from the bulk quantum theory. We address this question in an effective 3d quantum theory of pure gravity, which describes the high temperature regime of a holographic CFT. This theory can be viewed as a q-deformation and dimensional uplift of JT gravity. Using this model, we show that the Bekenstein-Hawking entropy of a two-sided black hole equals the bulk entanglement entropy of gravitational edge modes. In the conventional Chern-Simons description, these black holes correspond to Wilson lines in representations of PSL(2, ℝ) ⨂ PSL(2, ℝ). We show that the correct calculation of gravitational entropy suggests we should interpret the bulk theory as an extended topological quantum field theory associated to the quantum semi-group {textrm{SL}}_q^{+}left(2,mathbb{R}right)bigotimes {textrm{SL}}_q^{+}left(2,mathbb{R}right) . Our calculation suggests an effective description of bulk microstates in terms of collective, anyonic degrees of freedom whose entanglement leads to the emergence of the bulk spacetime.

Increased Temperature and Discharge Influence Overwinter Growth and Survival of Juvenile Salmonids in a Hydropeaking River: Simulating Effects of Climate Change Using Individual-Based Modelling

Climate change causes warming of rivers and may increase discharge, particularly during winter. Downstream of hydropower plants, fluctuating water temperature and flow create dynamic overwintering conditions for juvenile salmonids. We used inSTREAM 7.2-SD to simulate the effects of increased temperature (+2 °C) and discharge (+10%) on the overwinter growth and mortality of one-summer- and two-summer-old Atlantic salmon and brown trout in a river with a hydropeaking flow regime in a 2 × 2 design with replicated simulations. Water temperature had a major positive relationship with growth for both species and year classes, whereas increased flow alone had no major general effect on overwinter growth. For one-summer-old trout experiencing the high temperature regime, however, increased flow resulted in reduced growth. There were no major effects from temperature and flow on the survival rate of the two-summer-old fishes. On the other hand, there were significant interaction effects for the one-summer-olds, indicating that the effect of flow depended on temperature. For one-summer-old salmon, high flow resulted in increased survival in the low temperature regime, whereas it resulted in reduced survival in high temperature. In contrast, for one-summer-old trout, high flow resulted in reduced survival in the low temperature regime and increased survival in the high temperature. Different hydropower operation alternatives may interact with warming, affecting the relative competitive abilities of stream salmonids. Ecological models that predict the effects of different environmental conditions, such as temperature and flow regimes, may offer insight into such effects when in situ experiments are not feasible.

Correspondence between the Energy Equipartition Theorem in Classical Mechanics and Its Phase-Space Formulation in Quantum Mechanics.

In classical physics, there is a well-known theorem in which it is established that the energy per degree of freedom is the same. However, in quantum mechanics, due to the non-commutativity of some pairs of observables and the possibility of having non-Markovian dynamics, the energy is not equally distributed. We propose a correspondence between what is known as the classical energy equipartition theorem and its counterpart in the phase-space formulation in quantum mechanics based on the Wigner representation. Further, we show that in the high-temperature regime, the classical result is recovered.

Triangular lattice Hubbard model physics at intermediate temperatures

Moire systems offer an exciting playground to study many-body effects of strongly correlated electrons in regimes that are not easily accessible in conventional material settings. Motivated by a recent experiment on $\text{WSe}_2/\text{WS}_2$ moire bilayers [Y. Tang et al., Nature 579, 353-358 (2020)], which realizes a triangular superlattice with a small hopping (of approximately 10 Kelvin), with tunable density of holes, we explore the Hubbard model on the triangular lattice for intermediate temperatures $t \lesssim T < U$. Employing finite temperature Lanczos calculations, and closely following the fitting protocols used in the experiment, we recover the observed trends in the reported Curie-Weiss temperature $\Theta$ with filling, using the reported interaction strength $U/t=20$. We focus on the large increase of $|\Theta|$ on decreasing the density below half filling and the sign change of $\Theta$ at higher fillings, which signals the onset of ferromagnetism. The increase in $|\Theta|$ is also seen in the $t$-$J$ model (the low energy limit of the Hubbard model) in the intermediate temperature range, which we clarify is opposite to the trend in its high temperature limit. Differences between the low, intermediate and high temperature regimes are discussed. Our numerical calculations also capture the crossover between short-range antiferromagnetic to ferromagnetic order in the intermediate temperature regime, a result broadly consistent with the experimental findings. We find that this behavior is a finite-temperature remnant of the underlying zero temperature phase transition, which we explore with ground state density matrix renormalization group calculations. We provide evidence of ferromagnetism characterized by weak (but robust) correlations that explain the small $\Theta$ seen in the experiment.

Evaluation of the Impact of Urban Forestry on Urban Heat Island

The purpose of this study is to statistically evaluate the impact of urban forestry on urban heat Island in Umuahia city, located in Eastern Nigeria using Land Surface Temperature (LST) time series. The LST datasets were extracted from the Moderate Resolution Imaging Spectroradiometer (MODIS, MYD11A2 V6) satellite using Python and JavaScript in Google Earth Engine (GEE) platform. Two microclimate environments were considered namely: The Densely and sparsely populated areas in three different locations each. Each microclimate location had 976 observations starting from the 18th of February 2000 to the 1st of May 2021. The Auto-regressive Moving Average (ARMA) was used to model and predict the time series future points of each location; accuracy was measured using Mean Absolute Percentage Error (MAPE) and Root Mean Square Error (RMSE). The Land surface temperature of each selected microclimate location were monitored and the results showed an average observed temperatures difference of 2.90C between the Densely Populated and Sparsely Populated areas. In conclusion, the study showed that inhabitants of densely populated areas experience higher temperature regime than the inhabitants living within the sparsely populated areas. This increase in temperature within the densely populated could be attributed to the gradual loss of vegetation cover, which is due to man-made activities such as land use, land cover changes, industrial activities, vehicular movements, and the heat generated from buildings within the city. Thus, a spatial development planning strategy, which controls the growth of the built area and add green spaces should be created for a friendly urban environment.

Thermoelectric properties and scattering mechanisms in natural PbS

X-ray diffraction and energy dispersive x-ray spectroscopic analyses showed a natural galena (PbS) crystal from Freiberg in Saxony (Germany) to be a single phase specimen [rock salt (NaCl) structure type, space group $Fm\overline{3}m, a=5.932(1)$ \AA{}] with stoichiometric composition and an enhanced dislocation density ($\ensuremath{\delta}\ensuremath{\approx}{10}^{11}\phantom{\rule{0.16em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}2}$). The latter parameter leads to an increase of the electrical resistivity in the high-temperature regime, as well as to the appearance of phonon resonance with a characteristic frequency ${\ensuremath{\omega}}_{\mathrm{PR}}=3.8(1)$ THz. Being in the same range (i.e., 3--5.5 THz) with the sulfur optical modes of highest group velocities, it results in a drastic reduction (by $\ensuremath{\sim}$ 75%) of thermal conductivity ($\ensuremath{\kappa}$) at lower temperatures (i.e., $&lt;100$ K), as well as in the appearance of a characteristic minimum in $\ensuremath{\kappa}$ at $T\ensuremath{\approx}$ 30 K. Furthermore, the studied galena is characterized by phonon-drag behavior and by temperature dependent switch of the charge carrier scattering mechanism regime (i.e., scattering on dislocations for $T&lt;100$ K, on acoustic phonons for 100 K $&lt;T&lt;170$ K and on both acoustic and optical phonons for 170 K $&lt;T&lt;300$ K). The combined theoretical calculation and optical spectroscopic study confirm this mineral to be a direct gap degenerate semiconductor. The possible origins of the second-order Raman spectrum are discussed.

High temperature increases 2,4-D metabolism in resistant Amaranthus palmeri

AbstractPalmer amaranth (Amaranthus palmeri S. Watson) is a troublesome weed in several cropping systems in the United States. The evolution of resistance to multiple herbicides is a challenge for the management of this weed. Recently, we reported metabolic resistance to 2,4-D possibly mediated by cytochrome P450 (P450) activity in a six-way-resistant A. palmeri population (KCTR). Plant growth temperature can influence the herbicide efficacy and level of resistance. The effect of temperature on 2,4-D resistance in A. palmeri is unknown. In the present research, we investigated the response of KCTR and a known susceptible (MSS) A. palmeri response to 2,4-D grown under low-temperature (LT, 24/14 C, day/night [d/n]) or high-temperature (HT, 34/24 C, d/n) regimes. When MSS and KCTR plants were 8- to 10-cm tall, they were treated with 0, 140, 280, 560 (field recommended dose), 1,120, and 2,240 g ai ha−1 of 2,4-D. Further, 8- to 10-cm-tall MSS and KCTR plants grown at LT and HT were also treated with [14C]2,4-D to assess the metabolism of 2,4-D at LT and HT. The results of dose–response experiments suggest that KCTR A. palmeri exhibits 23 times more resistance to 2,4-D at HT than MSS. Nonetheless, at LT, the resistance to 2,4-D in KCTR was only 2-fold higher than in MSS. Importantly, there was enhanced metabolism of 2,4-D in both KCTR and MSS A. palmeri at HT compared with LT. Further, treatment with the P450 inhibitor malathion, followed by 2,4-D increased the susceptibility of KCTR at HT. Overall, rapid metabolism of 2,4-D increased KCTR resistance to 2,4-D at HT compared with LT. Therefore, the application of 2,4-D when temperatures are cooler can improve control of 2,4-D–resistant A. palmeri.