Temperature-dependent Changes Research Articles

Molecular Dynamics Simulation of Clay Mineral–Water Interfaces: Temperature-Dependent Structural, Dynamical, and Mechanical Properties

Water interacting with clay minerals—such as kaolinite, montmorillonite, and pyrophyllite—fundamentally governs their geotechnical and environmental functions, thereby influencing parameters such as retention, transport, and stability. Understanding the effects of temperature on water behavior within clay mineral interlayers is critical for predicting the performance of clay–water systems under dynamic environmental conditions. This study performed molecular dynamics simulations to investigate the structural, dynamical, and mechanical properties of interlayer water in three representative clay minerals over a temperature range of 298.15–363.15 K. Our analyses focused on mean squared displacement (MSD), density profiles, hydrogen bond dynamics, and stress distributions, thereby revealing the interaction between water structuring and thermal fluctuations. Results indicated distinct temperature-dependent changes in water diffusion and hydrogen bond stability, with montmorillonite consistently exhibiting enhanced water retention and steadier hydrogen bonding networks across the studied temperature spectrum. Density profiles highlighted pronounced confinement effects at lower temperatures that gradually diminish with increasing thermal energy. Concurrently, the stress distributions revealed the mechanical responses of clay–water interfaces, highlighting the interplay between thermal motion of water molecules and their interactions with the clay surfaces. These findings offer valuable insights into how temperature regulates water behavior in clay mineral interlayers and provide a foundation for advancing predictive modeling and the design of engineered systems in water-rich, thermally variable environments.

Field switching of microfabricated metamagnetic FeRh MRI contrast agents

In a step towards generating switchable MRI cellular labels, we demonstrate in-situ field switching of micron scale metamagnetic Iron-Rhodium (FeRh) thin film particles. A thin-film (200 nm) FeRh sample was fabricated and patterned into an array of progressively smaller squares with sizes ranging from 500 μm down to 1 μm. The large first order phase change from antiferromagnetic to ferromagnetic state was characterized using vibrating sample magnetometry, magnetic force microscopy, and MRI. Room temperature MRI experiments sensitive to the local magnetic field surrounding the particles demonstrated the low moment state (OFF MRI contrast) at 4.7T and high moment state (ON MRI contrast) at 11.7T for the array where sizes down to 2–3 μm were observed in MRI at 50 μm resolution. The expected temperature dependent MRI contrast change was seen at 4.7T, where 10 μm particles could be observed at 150 μm resolution in the ON state. A shielded MRI insert, used to temporarily increase or decrease the magnetic field up to 0.77T amplitude, was used to reversibly switch the particle array at constant temperature and blink the particles ON and OFF at 4.7T. This work demonstrates the MRI contrast switching potential for FeRh particles with biological cell dimensions, and the use of magnetic field pulses for reversible MRI label contrast control.

Temperature-Dependent Structural Changes of the Active Site and Substrate-Binding Cleft in Hen Egg White Lysozyme

Lysozyme plays a crucial role in the natural immune system, protecting against invading bacteria or viruses. The room-temperature (RT) structure of lysozymes is important for understanding accurate structural information compared to the crystal structure determined at cryogenic temperature. Several RT structures of lysozymes are determined by serial crystallography, but their temperature-dependent structural properties are not fully elucidated. To better understand the temperature-dependent structural change, the RT and cryogenic temperature structures of hen egg white lysozyme (HEWL) were determined by serial synchrotron crystallography (SSX) and macromolecular crystallography (MX), respectively. Structural comparisons of HEWLRT and HEWLCryo showed that the positions of the loops above the substrate-binding cleft of HEWL differed. The width of the substrate-binding cleft between the α- and β-domains of HEWLRT was wider than that of HEWLCryo. The distance between the two catalytic residues Glu53 and Asp70 and their interaction with neighbor residues and water molecules showed the distant between HEWLRT and HEWLCryo. Due to temperature, the subtle movements of the active site and substrate-binding cleft of HEWL led to different docking results for N-acetylglucosamine and N,N′,N″-triacetylchitotriose. These results will provide useful information to more accurately understand the molecular function of HEWL and insights into the temperature effects for ligand design.

Confocal Raman Microscopy for Measuring In Situ Temperature-Dependent Structural Changes in Poly(Ethylene Oxide) Thin Films.

Crystallization from the melt is a critical process governing the properties of semi-crystalline polymeric materials. While structural analyses of melting and crystallization transitions in bulk polymers have been widely reported, in contrast, those in thin polymer films on solid supports have been underexplored. Herein, in situ Raman microscopy and self-modeling curve resolution (SMCR) analysis are applied to investigate the temperature-dependent structural changes in poly(ethylene oxide) (PEO) films during melting and crystallization phase transitions. By resolving complex overlapping sets of spectra, SMCR analysis reveals that the thermal transitions of 50 µm thick PEO films comprise two structural phases: an ordered crystalline phase and a disordered amorphous phase. The ordered structure of the crystalline PEO film entirely disappears as the polymer is heated; conversely, the disordered structure of the amorphous PEO film reverts to the ordered structure as the polymer is cooled. Broadening of the Raman bands was observed in PEO films above the melting temperature (67 °C), while sharpening of bands was observed below the crystallization temperature (45 °C). The temperatures at which these spectral changes occurred were in good agreement with differential scanning calorimetry (DSC) measurements, especially during the melting transition. The results illustrate that in situ Raman microscopy coupled with SMCR analysis is a powerful approach for unraveling complex structural changes in thin polymer films during melting and crystallization processes. Furthermore, we show that confocal Raman microscopy opens opportunities to apply the methodology to interrogate the structural features of PEO or other surface-supported polymer films as thin as 2 µm, a thickness regime beyond the reach of conventional thermal analysis techniques.

Microstructural Characteristics of Damaged Hot Dry Rock Flow Network Stimulated by Cryogenic Liquid Nitrogen Shock.

Hot dry rock (HDR) geothermal development faces challenges due to the difficulty of stimulating fluid flow and heat-exchange fracture channels within deep, low-porosity, and low-permeability reservoirs. A liquid nitrogen cyclic cold shock method was proposed, using liquid nitrogen as a fracturing fluid. The large temperature difference between the liquid nitrogen and the hot rock induces thermal stress, forming a complex pore-fracture network. In this study, HDR samples at various temperatures were subjected to 5 cycles of liquid nitrogen cold shock. Pore-fracture structures of the damaged cores were tested by low-field nuclear magnetic resonance and X-ray microscopy. Results showed temperature-dependent changes in porosity: at 200 and 300 °C, small-size pores rose, with maximum porosities of 3.13% and 3.37%; at 400-500 °C, large-size pores rose, with porosities reaching 4.59% and 12.76%. Different pore types exhibited distinct responses: mesopores are the most sensitive to temperature shock, micropores responded to the early damage stage, and macropores only responded under high-temperature differences and multiple cycles. Multifractal analysis revealed increased heterogeneity and concentration in pore distribution with damage escalation. The slice porosity, fractal box dimension, and probability entropy demonstrated exponential growth. Results indicate that temperature difference is the main controlling factor of pore damage in HDR, and cyclic shock can also contribute to continuous pore development. There is a high correlation between pore-fracture parameters and multifractal parameters, allowing the multifractal to reflect a more complex pore-fracture structure quantitatively.

Thermoelectrochemical Method for Quantification of the Micellization Entropy of Redox-Active Polymers.

Redox-active micelles undergo reversible association and dissociation in response to their redox potential and are promising materials for various applications, such as drug delivery and bioimaging. Evaluation of the micellization entropy is critical in controlling the thermodynamics of micelle formation. However, conventional methods such as isothermal titration calorimetry and surface tensiometry require a long measurement time to observe changes in the heat flow or the surface tension caused by the micellization. Here we report a thermoelectrochemical method to quantify the entropy change produced by redox-active micelles. A set of poly(ethyl glycidyl ether-b-ethylene oxide)phenothiazine (PT-EGE-EO) with varied chain length were synthesized, and their micellization entropy was calculated from the temperature-dependent changes of the equilibrium potential. This thermoelectrochemical method enables a quick evaluation of the micellization entropy with only a single sample preparation and temperature sweep. The obtained results showed a reasonable agreement with the conventional surface tensiometry and isothermal titration calorimetry, indicating that the thermoelectrochemical method is a promising alternative for quantification of the micellization entropy.

Pseudomorphic Transformation in Nanostructured Thiophene-Based Materials.

This study reveals the capability of nanostructured organic materials to undergo pseudomorphic transformations, a ubiquitous phenomenon occurring in the mineral kingdom that involves the replacement of a mineral phase with a new one while retaining the original shape and volume. Specifically, it is demonstrated that the postoxidation process induced by HOF·CH3CN on preformed thiophene-based 1D nanostructures preserves their macro/microscopic morphology while remarkably altering their electro-optical properties by forming a new oxygenated phase. Experimental evidence proves that this transformation proceeds via an interface-coupled dissolution-precipitation mechanism, leading to the growth of a porous oxidized shell that varies in thickness with exposure time, enveloping the pristine smooth core. The oxygenated species exhibits stronger electron-acceptor characteristics than the core material, promoting charge transfer state formation, as confirmed by microspectroscopy and DFT calculations. This enables (i) precise modulation of the nanostructure's surface potential, allowing for the formation of entirely organic heterojunctions with precise spatial resolution via wet chemical processing; (ii) effective doping of the nanostructure, resulting in a strong change of the conductivity temperature dependence and a switch between a low and high conduction state depending on the applied bias. Overall, this work showcases an approach to engineering "impossible" composite architectures with pre-established morphology and tailored chemical-physical properties.

Heating-Induced Redox Property Dynamics of Peat Soil Dissolved Organic Matter in a Simulated Peat Fire: Electron Exchange Capacity and Molecular Characteristics.

Peatlands store one-third of the world's soil organic carbon. Globally increased fires altered peat soil organic matter chemistry, yet the redox property and molecular dynamics of peat-dissolved organic matter (PDOM) during fires remain poorly characterized, limiting our understanding of postfire biogeochemical processes. Clarifying these dynamic changes is essential for effective peatland fire management. This study demonstrates temperature-dependent dynamic changes in the electron exchange capacity (EEC) of PDOM by simulating peat soil burning, significantly affecting microbial iron reduction. At low fire temperatures (200-250 °C), the EEC remains constant by releasing more phenolic moieties to enhance the electron-donating capacity (EDC). Higher temperatures (500 °C) diminish 90% of the EEC by consuming phenolic-quinone moieties. Pyrolytic PDOM (pyPDOM) contributes to 40% of the EEC of peat soil, with this contribution declining at higher temperatures. Phenolic-quinone moieties remain the primary redox-active moieties in pyPDOM. Fourier transform ion cyclotron resonance mass spectrometry analysis shows that postfire EDC depends more on phenolic types than abundance, with monophenol-like molecules (C < 12) being more significant than polyphenol-like (C ≥ 12). Quinone moieties in pyPDOM are associated with high-oxygen condensed aromatics, and their depletion reduces the electron-accepting capacity, weakening its electron shuttle effect in microbial iron reduction. Our findings enhance the understanding of the changes in PDOM redox properties during fires.

A Compensated Clock: Temperature and Nutritional Compensation Mechanisms Across Circadian Systems.

Circadian rhythms are ∼24-h biological oscillations that enable organisms to anticipate daily environmental cycles, so that they may designate appropriate day/night functions that align with these changes. The molecular clock in animals and fungi consists of a transcription-translation feedback loop, the plant clock is comprised of multiple interlocking feedback-loops, and the cyanobacterial clock is driven by a phosphorylation cycle involving three main proteins. Despite the divergent core clock mechanisms across these systems, all circadian clocks are able to buffer period length against changes in the ambient growth environment, such as temperature and nutrients. This defining capability, termed compensation, is critical to proper timekeeping, yet the underlying mechanism(s) remain elusive. Here we examine the known players in, and the current models for, compensation across five circadian systems. While compensation models across these systems are not yet unified, common themes exist across them, including regulation via temperature-dependent changes in post-translational modifications.

Relaxation Phenomena in Low-Density and High-Density Polyethylene.

A study was conducted on the internal friction spectra and temperature dependencies of the frequency of free damped oscillatory processes excited in the investigated samples of low-density polyethylene (LDPE) and high-density polyethylene (HDPE) over a temperature range from -150 °C to +150 °C. It was found that the internal friction spectra exhibit several local dissipative processes of varying intensity, which manifest in different temperature intervals. The structure of the internal friction spectra and the peaks of dissipative losses are complex, as evidenced by the occurrence of sharp, locally temperature-dependent jumps in the intensity of dissipative losses observed throughout the entire temperature range. A theoretical analysis was performed to explore the relationship between the anomalous change in the frequency of the oscillatory process and the defect in the shear modulus, as well as the mechanisms of internal friction for the most intense dissipative loss processes identified in the internal friction spectra. A significant difference was revealed in the structure of the internal friction spectra of LDPE and HDPE in the temperature range of -50 °C to +50 °C. A comparison of the LDPE and HDPE samples was conducted based on changes in their strength characteristics, taking into account the locally temperature-dependent changes in the shear modulus caused by local dissipative losses observed in the internal friction spectra.

Temperature-dependent effect of nanoscale phase change materials on fresh and hardened cement-based mortar

As smart and innovative materials, temperature-dependent phase change materials (PCMs) can be used to produce environmentally friendly energy-saving concrete. In this study, the fresh and hardened concrete properties of mortars incorporating PCMs in different ratios (0%, 2.5% and 5%) were experimentally investigated. Rheological properties such as slump flow, specific viscosity and yield stress were determined at different temperatures (20–50°C). Time-dependent physical, mechanical and thermal properties such as ultrasound pulse velocity (UPV), electrical resistivity, dynamic modulus of elasticity and compressive and flexural strengths were determined. Thermogravimetric analysis and thermal conductivity tests were also carried out. The experimental findings showed that the workability and hardened properties of mortars decreased with the addition of PCM. However, the rheological properties of the fresh mortar changed depending on the temperature due to the PCM absorbing heat. Therefore, the fresh properties of mortar with PCMs can be controlled by temperature. It was also found that the phase change of mortars with PCM could be obtained by measuring the electrical resistivity or UPV at different temperatures.

Transcriptomic and metabolomic insights into temperature-dependent changes in catechin and anthocyanin accumulation in tea plants with different leaf colors

Transcriptomic and metabolomic insights into temperature-dependent changes in catechin and anthocyanin accumulation in tea plants with different leaf colors

Predicting population-level impacts of projected climate heating on a temperate freshwater fish.

Climate heating has the potential to drive changes in ecosystems at multiple levels of biological organization. Temperature directly affects the inherent physiology of plants and animals, resulting in changes in rates of photosynthesis and respiration, and trophic interactions. Predicting temperature-dependent changes in physiological and trophic processes, however, is challenging because environmental conditions and ecosystem structure vary across biogeographical regions of the globe. To realistically predict the effects of projected climate heating on wildlife populations, mechanistic tools are required to incorporate the inherent physiological effects of temperature changes, as well as the associated effects on food availability within and across comparable ecosystems. Here we applied an agent-based bioenergetics model to explore the combined effects of projected temperature increases for 2100 (1.4, 2.7, and 4.4°C), and associated changes in prey availability, on three-spined stickleback (Gasterosteus aculeatus) populations representing latitudes 50, 55, and 60°N. Our results showed a decline in population density after a simulated 1.4°C temperature increase at 50°N. In all other modeled scenarios there was an increase (inflation) in population density and biomass (per unit area) with climate heating, and this inflation increased with increasing latitude. We conclude that agent-based bioenergetics models are valuable tools in discerning the impacts of climate change on wild fish populations, which play important roles in aquatic food webs.

Revealing an origin of temperature-dependent structural change in intrinsically disordered proteins.

Intrinsically disordered proteins (IDPs) show structural changes stimulated by changes in external conditions. This study aims to reveal the temperature dependence of the structure and the dynamics of the intrinsically disordered region of the helicase-associated endonuclease for fork-structured DNA, one of the typical IDPs, using an integrative approach. Small-angle X-ray scattering (SAXS) and circular dichroism (CD) studies revealed that the radius of gyration and ellipticity at 222nm remained constant up to 313-323 K, followed by a decline above this temperature range. NMR studies revealed the absence of a promotion of the α helix. As a result, SAXS, CD, and NMR data strongly suggest that these temperature-dependent structural changes were primarily due to a reduction in the content of the polyproline II (PPII) helix. Moreover, quasielastic neutron scattering studies revealed a slight change in the activation energy in a similar temperature range. Considering the concept of glass transition, it is posited that dynamical cooperativity between the PPII helix and water may play a significant role in these structural changes. The findings suggest that internal dynamics are crucial for regulating the structure of IDPs, highlighting the importance of considering dynamical cooperativity in future studies of protein behavior under varying temperature conditions.

A Bayesian Inference Approach to Accurately Fitting the Glass Transition Temperature in Thin Polymer Films.

We present a Bayesian inference-based nonlinear least-squares fitting approach developed to reliably fit challenging, noisy data in an automated and robust manner. The advantages of using Bayesian inference for nonlinear fitting are demonstrated by applying this approach to a set of temperature-dependent film thickness h(T) data collected by ellipsometry for thin films of polystyrene (PS) and poly(2-vinylpyridine) (P2VP). The glass transition experimentally presents as a continuous transition in thickness characterized by a change in slope that in thin films with broadened transitions can become particularly subtle and challenging to fit. This Bayesian fitting approach is implemented using existing open-source Python libraries that make these powerful methods accessible with desktop computers. We show how this Bayesian approach is more versatile and robust than existing methods by comparing it to common fitting methods currently used in the polymer science literature for identifying T g. As Bayesian inference allows for fitting to more complex models than existing methods in the literature do, our discussion includes an in-depth evaluation of the best functional form for capturing the behavior of h(T) data with temperature-dependent changes in thermal expansivity. This Bayesian fitting approach is easily automated, capable of reliably fitting noisy and challenging data in an unsupervised manner, and ideal for machine learning approaches to materials development.

A novel proxy for energy flux in multi-era wildfire reconstruction

Escalations in wildfire activity are of significant global concern, particularly within vulnerable wetland ecosystems integral to natural carbon sequestration and climate change mitigation. Our understanding and management of future wildfire activity may be better contextualised through the study of historic and ancient fire records, independent of human influence. Methods of study include ‘geothermometry’ - approximating ancient fire intensity from temperature-dependent changes in the chemistry of fossil charcoal. Though well established in their relation to experimental charcoalification, these methods still fail to quantify the true intensity of ancient fires, as a measure of energy release. As a result, their applicability, and contributions to the characterisation of modern fire activity, remain uncertain. Here, we present a novel measure of wildfire energy release, as a proxy for true intensity, through the co-application of cone calorimetry and Raman spectroscopy of charcoal. By applying a range of wildfire heat fluxes to variable peatland fuel mixes, this research demonstrates the complexity in correlating fire behaviour and charcoal microstructure. Further statistical analyses suggest a correlation between spectroscopic results, measures of CO and CO2 release, and fire severity. This offers a principal measure of ancient wildfire intensity, consistent with modern practices in wildfire modelling, monitoring, and management.

Luminescence Thermochromism of a Noncluster Copper Iodide Complex.

Hybrid copper(I) halide materials are currently attracting significant attention due to their exceptional luminescence properties, offering great potential for the development of multifunctional emissive materials with, in addition, eco-friendly features. A binuclear copper iodide complex, based on the [Cu2I2L4] motif with phosphite derivatives as ligands, has been synthesized and structurally characterized. Photophysical investigations indicate that this complex displays luminescence thermochromic properties, which are characterized by a temperature-dependent change in the relative intensity of two emission bands. The high-contrast luminescence thermochromism, with an important color variation from purple to cyan, is ascribed to the thermal equilibrium of two different excited states. While thermochromism is relatively known for multimetallic complexes, the perfectly controlled thermochromism of the studied compound is unprecedented for a binuclear complex. From theoretical investigations, this original feature is due to the coordination of phosphite ligands, which induces a specific energy layout of the complex, presenting vacant orbitals of varying nature. This single-component, dual-emissive binuclear complex, displaying relevant sensitivity temperature response, presents great potential for luminescence ratiometric thermometry applications. This study underlines the relevance of the ligand engineering strategy in developing original, emissive, and sustainable copper-based materials.

Adsorption and removal of herbicide paraquat from aqueous solutions via novel bimetal organic framework: Kinetics, equilibrium and statistical surface modeling

This study examines the adsorption and removal of the herbicide paraquat in relation to a bimetal organic framework known as the Terbium/Palladium Metal-Organic Framework (Tb/Pd-MOF). Analysis of N2 adsorption/desorption isotherms, which were used to assess the properties of the Tb/Pd-MOF, revealed that the absorption of paraquat on Tb/Pd-MOF resulted in a reduction in pore volume, pore size, and surface area. Specifically, the pore volume decreased from 8.25 to 5.68 cm3/g, the pore size decreased from 11.34 nm to 8.92 nm, and the surface area decreased from 1456.61 to 1262.82 m2/g. The pore radius also decreased from 0.96 nm to 0.58 nm. Tb/Pd-MOF’s functional groups were identified through FT-IR, and the structure of the compound was confirmed using XPS. Various adsorption parameters including temperature, adsorbent dosage, pH, paraquat concentration, and contact time were studied. Density functional theory (DFT) was used to understand the electrical properties, reactivity, and morphology of paraquat. Results from the DFT analysis revealed that the electrophilic and nucleophilic attack sites aligned with the molecular orbitals (HOMO and LUMO) and MEP outcomes. The study found that Tb/Pd-MOF demonstrated a significant absorption capacity for paraquat, with adsorption data consistent with the Langmuir isotherm and pseudo-second-order kinetic models. The paraquat adsorption capability of Tb/Pd-MOF was determined to be 574.8 mg/g. Furthermore, chemisorption was identified as the primary form of adsorption, as indicated by the adsorption energy of 26.98 kJ·mol−1. The optimal conditions for achieving a high adsorption capacity were identified as pH 8 and 0.02 g of Tb/Pd-MOF. The temperature-dependent changes in the thermodynamic parameters ΔG°, ΔH°, and ΔS° indicated that the paraquat absorption onto Tb/Pd-MOF occurred spontaneously, was endothermic, and involved random processes. To optimize the absorption process, Response Surface Methodology and Box-Behnken design (RSM, BBD) were employed. These techniques enabled effective removal of paraquat from the Tb/Pd-MOF material. During chemisorption, the adsorbate and adsorbent form chemical bonds, while aromatic rings are involved in π-π bonding. Additionally, pore-filling occurs when the adsorbate fills the pores of the adsorbent, and electrostatic interactions result from the attraction or repulsion of charges between the adsorbate and adsorbent. As a means of eliminating paraquat from wastewater, Tb/Pd-MOF demonstrates significant potential due to its diverse absorption processes and high capacity for adsorption.

Chlorophyll and Carotenoid Metabolism Varies with Growth Temperatures among Tea Genotypes with Different Leaf Colors in Camellia sinensis

The phenotype of albino tea plants (ATPs) is significantly influenced by temperature regimes and light conditions, which alter certain components of the tea leaves leading to corresponding phenotypic changes. However, the regulatory mechanism of temperature-dependent changes in photosynthetic pigment contents and the resultant leaf colors remain unclear. Here, we examined the chloroplast microstructure, shoot phenotype, photosynthetic pigment content, and the expression of pigment synthesis-related genes in three tea genotypes with different leaf colors under different temperature conditions. The electron microscopy results revealed that all varieties experienced the most severe chloroplast damage at 15 °C, particularly in albino cultivar Baiye 1 (BY), where chloroplast basal lamellae were loosely arranged, and some chloroplasts were even empty. In contrast, the chloroplast basal lamellae at 35 °C and 25 °C were neatly arranged and well-developed, outperforming those observed at 20 °C and 15 °C. Chlorophyll and carotenoid measurements revealed a significant reduction in chlorophyll content under low temperature treatment, peaking at ambient temperature followed by high temperatures. Interestingly, BY showed remarkable tolerance to high temperatures, maintaining relatively high chlorophyll content, indicating its sensitivity primarily to low temperatures. Furthermore, the trends in gene expression related to chlorophyll and carotenoid metabolism were largely consistent with the pigment content. Correlation analysis identified key genes responsible for temperature-induced changes in these pigments, suggesting that changes in their expression likely contribute to temperature-dependent leaf color variations.

Diffusion in Polymethylene Chain Solutions with a Polar Component.

A hydrodynamic bead model based on Kirkwood-Riseman theory has been used to calculate the translational diffusion constant, D, for solutes with polymethylene chains in solutions with a polar component. A comparison with the experimental values for nonpolar n-alkanes in polar 2-propanol, tetrahydrofuran, chlorobenzene, chloroform, 1-octanol, quinoline, and chloroform (78 D values) and polar primary alcohols in nonpolar benzene and n-octane (24 D values) gives an average absolute percentage difference of ∼3% between the 102 experimental and calculated D values. Consideration of the solvent's temperature-dependent changes in the degree of aggregation due to hydrogen bonding was necessary for the n-alkanes in 1-octanol. Good agreement was not found for primary alcohols in 1-octanol due to solute-solvent hydrogen bonding. A correlation that depends on the solutes' molar volumes instead of their chain lengths gives worse agreement than the bead model for the n-alkanes in polar solvents and primary alcohols and n-alkanes in nonpolar solvents.