Differences In Thermal Responses Research Articles

Temperature differentially regulates estuarine microbial N2O production along a salinity gradient

Nitrous oxide (N2O) is atmospheric trace gas that contributes to climate change and affects stratospheric and ground-level ozone concentrations. Ammonia oxidizers and denitrifiers contribute to N2O emissions in estuarine waters. However, as an important climate factor, how temperature regulates microbial N2O production in estuarine water remains unclear. Here, we have employed stable isotope labeling techniques to demonstrate that the N2O production in estuarine waters exhibited differential thermal response patterns between nearshore and offshore regions. The optimal temperatures (Topt) for N2O production rates (N2OR) were higher at nearshore than offshore sites. 15N-labeled nitrite (15NO2-) experiments revealed that at the nearshore sites dominated by ammonia-oxidizing bacteria (AOB), the thermal tolerance of 15N-N2OR increases with increasing salinity, suggesting that N2O production by AOB-driven nitrifier denitrification may be co-regulated by temperature and salinity. Metatranscriptomic and metagenomic analyses of enriched water samples revealed that the denitrification pathway of AOB is the primary source of N2O, while clade II N2O-reducers dominated N2O consumption. Temperature regulated the expression patterns of nitrite reductase (nirK) and nitrous oxide reductase (nosZ) genes from different sources, thereby influencing N2O emissions in the system. Our findings contribute to understanding the sources of N2O in estuarine waters and their response to global warming.

Comparison of nylon, vicryl, and fibrin glue for nerve grafting in rats

ABSTRACT Objectives For nerve injuries, not amendable to tensionless epineural coaptation of the nerve, autografts are the preferred treatment. Although absorbable sutures are not recommended for nerve repair, there is no evidence that non-absorbable sutures are superior to absorbable sutures. This study aims to assess the effectiveness of non-absorbable monofilament nylon sutures, absorbable monofilament vicryl sutures, and fibrin glue when used for nerve grafting. Methods Lewis rats (N = 32) were subjected to a sciatic nerve transection and randomly assigned to a group: graft with Nylon, graft with Vicryl, graft with Fibrin Glue, or no graft. Motor function, sensory function, and thermal pain were assessed during a 12-week recovery period, and immunohistochemistry was used to assess macrophage response. Results At 12 weeks, the Vicryl and Nylon groups had significantly larger ankle angles at to lift off, which is a measure of motor function, compared to injured controls (p < 0.05). Grafted rats displayed no difference in thermal response but hypersensitivity to mechanical stimuli compared to the uninjured hindlimb. The Nylon, Vicryl, and Fibrin Glue groups all had significantly less atrophy of the gastrocnemius muscle compared to injured controls (p < 0.0001). In the Fibrin Glue group, 3/9 grafts did not incorporate. The Nylon group had significantly less (p = 0.0004) axon growth surrounding the suture holes compared to the Vicryl group. There were no differences in the axon counts, motor neurons, or sensory neurons between all grafted rats. Conclusions These results demonstrate that vicryl sutures work just as well as nylon for nerve recovery after injury and grafting.

Thermophysiological responses and thermal comfort of occupants in indoor spaces under different speaking and non-speaking conditions

As speaking is one of the fundamental behaviours in human activities, understanding the thermal comfort of occupants during speaking is crucial to providing a satisfactory environment. To further strengthen this understanding and identify how occupant thermal responses change during speaking activities, this study performs an experiment to examine the thermophysiological parameters and thermal comfort of occupants across three different speaking and non-speaking conditions: (1) silent (i.e., non-speaking); (2) speech (i.e., continuous speaking); and (3) conversation (i.e., intermittent speaking). During the experiment, thermophysiological parameters, including skin temperature, electrodermal activity, and heart rate, were collected using smart wristbands from 30 subjects at three different temperature settings to represent three distinct thermal environmental conditions: (1) Cold: 20 °C; (2) Neutral: 24 °C; and (3) Hot: 28 °C. Subjects were also required to report their thermal comfort perceptions in terms of thermal sensation votes, thermal preference votes, and thermal satisfaction votes. Repeated measures ANOVA test and Friedman test were used to analyse the thermophysiological parameters and thermal comfort perceptions. The null hypothesis, which suggests no significant differences in thermal responses and comfort across the three speaking conditions, will be rejected at a significance level of 0.05 (two-tail). The results revealed significant differences in all three thermophysiological parameters between speaking conditions at all temperature settings, while the thermal comfort perception did not consistently show statistically significant differences between speaking conditions. The findings contribute to our understanding of the relationship between communication and thermal responses, highlighting the importance of contextual factors in designing comfortable environments for speaking-related activities.

Dual‐Mode Thermal Responses in Red and Near‐Infrared Emission Channels via Manipulating Cross Relaxations

AbstractLead‐free double perovskites with multi‐mode emission characters are highly desired for optoelectronic devices. Herein, dual‐mode thermal responses with low thermal quenching in the red emission channel and high thermal quenching in the near‐infrared (NIR) channel are achieved in a holmium‐based double perovskite (Cs2NaHoCl6). The temperature‐dependent emission is modulated by manipulating three cross relaxations of CR1 (5F4, 5I7) → (5F5, 5I6), CR2 (5S2, 5I8) → (5F5, 5I7), and CR3 (5F5, 5F5) → (5I7, 5G4) through adjusting the concentration of Ho3+. The difference in thermal response between the red and NIR emissions becomes more pronounced with a higher concentration of Ho3+ up to 100%, while the two emissions show almost the same thermal quenching behavior when the Ho3+ concentration is below 20%. To demonstrate their applications, a thermal‐responsive dual‐mode information encryption system and a NIR emitting LED with night vision capacity are fabricated using the prepared samples. This study provides a new approach for thermal quenching regulation in rare‐earth‐based lead‐free perovskites and illustrates their potential in lighting, anti‐counterfeiting, and sensing applications.

Experimental Study on Differential Thermal Response and Pore-Fracture Structure Evolution Characteristics of Coals under Microwave Irradiation: A Case Study of Five Different Rank Coals

Experimental Study on Differential Thermal Response and Pore-Fracture Structure Evolution Characteristics of Coals under Microwave Irradiation: A Case Study of Five Different Rank Coals

The climate backgrounds of urban migrants affect thermal response

Human thermal responses can vary based on individuals' thermal histories. Although comparative studies on thermal comfort have been conducted in different regions, research is still limited regarding the differences in thermal responses among people living in the same city but having emigrated from diverse climates. Addressing this gap, this study, conducted in Beijing between 2021 and 2022, involved on-site meteorological measurements and questionnaire surveys, collecting a total of 1,370 questionnaires. The objective was to examine the differences in thermal response among individuals from different climatic backgrounds post-migration and assess the implications for urban design improvements. The study findings revealed the following: 1) Southern migrants exhibited a higher neutral Universal Thermal Climate Index (UTCI) compared to northern migrants (20.2 °C vs. 18.7 °C). 2) In terms of the acceptable temperature range (TAR) for 1 h, southern migrants showed a greater tolerance for hot conditions compared to northern migrants (4.4–30.8 °C vs. 0.6–28.6 °C), but less tolerant for cold conditions. 3) The transient acceptable range was considerably wider than the 1-h TAR. 4) Residents feeling thermally neutral at present had lower demands for urban design improvements. Our results highlight the importance of considering diversity of thermal response and implementing targeted management and planning interventions. The study is expected to provide practical recommendations for creating more livable and sustainable urban environments.

Insecticide resistant mosquitoes remain thermal stress resistant, without loss of thermal plasticity

A major component of mosquito's climate change response is their heat tolerance, and any ability to rapidly adjust to extreme environmental conditions through phenotypic plasticity. The excessive use of insecticides for the control of major mosquito species leads to resistant populations, however it is largely unclear if this concurrently impacts thermal stress resistance and their potential to adjust tolerance via phenotypic plasticity. Culex pipiens pipiens, Culex pipiens molestus and Aedes albopictus populations obtained from the same region were subjected for 12 generations to selection trials to larvicides Diflubenzuron (DFB) and Bacillus thuringiensis subsp. israelensis (Bti) to develop insecticide resistance. Adults emerging from the selected populations were acclimated at different temperatures and the upper and lower critical thermal limits (CTmax and CTmin) were estimated using dynamic thermal assays. In addition, the supercooling points (SCPs) of non-acclimated adults of resistant and control populations were determined. Our results revealed marked differences in thermal response among the three species, the different acclimation regimes and sexes. Aedes albopictus was more resistant in high than low temperatures compared to both Culex pipiens biotypes. Culex forms responded similarly to heat but differently to cold stress. In both forms, females responded better than males to all thermal stressors. Acclimation at higher and lower temperatures improves CTmax and CTmin values, respectively in both insecticide resistant and control populations of all three species. Overall, selection to insecticides did not affect the thermal performance of adults. Hence, insecticide-resistant mosquito populations perform similarly to untreated ones and are capable of readily adapting to new environmental changes rising concerns regarding their geographic range expansion and disease transmission globally.

Analysis of Cold/Hot Spot Effect in Flight Test Heat Flux Measurement

In model flight tests, the cold/hot spot effect often occurs due to the difference in thermal response between the heat flux sensor and surrounding thermal protection materials, which affects the heat flux measurement. In severe cases, the measurement deviation may even exceed 100%. This article analyzes the flight data of the space model flight test MF-1 and finds that there is a significant hot spot effect. This paper reproduces the temperature measurement process of MF-1 thin-skin structure along the trajectory through aerodynamic thermal/heat transfer coupling calculations. The difference between the flight data and the coupling calculation results is compared and analyzed. Based on the flight test of MF-1, the formation mechanism of the cold/hot spot effect and its impact on wall heat flux are studied. It is found that local temperature discontinuities can generate an additional wall-normal velocity near the wall, which will generate an additional wall-normal convective heat transfer, further increasing the measurement deviation of wall heat flux. The research results of this paper have important guiding significance for the development of heat flux sensors for aerospace model flight tests and correctly conducting heat flux measurements.

Developing thermal prediction models for the elderly under temperature step changes

Daily transitions between indoor and outdoor environments involving temperature step changes have been extensively studied in young people, but little attention has been given to age-related differences and the development of thermal prediction models specifically for the elderly. To address this knowledge gap, a study was conducted in a climate chamber using warm-neutral-warm experimental sessions. Twenty-four elderly participants were selected from volunteers who met the health and body shape requirements. Thermal sensation vote (TSV) and mean skin temperature (MST) responses of the elderly were collected and analyzed. The results demonstrate that temperature step changes (3–9 °C) and neutral thermal experiences significantly influence the thermal responses of the elderly. Compared to the young, the elderly exhibit lower TSV, lower MST, lower skin heat loss, and different associations between TSV and skin heat loss. Leveraging these age-related differences, an MST prediction model was established for the elderly. The predicted MST can also serve as an input for the TSV prediction model established in this study. The TSV prediction model is based on skin heat loss and applicable to both transient and steady-state conditions. This study introduces a new approach for predicting the thermal responses of the elderly and enhances understanding of age-related differences in thermal responses.

Responses of Stream Water Temperature to Water Levels in Forested Catchments of South Korea

Event flow characteristics were evaluated based on temperature and level of stream water in 22 forested catchments (area: 13.2–281.4 ha) to investigate sustainable flood management measures. Temperature and stream water levels were during 346 rainfall events in the summer season (July–September) from 2020 to 2022. Rising stream water levels responded to falling stream water temperature between ≤100 and &gt;100 ha forested catchments in two types of time of concentration. Stream water temperature decreased by 3.0 °C when the stream water level increased by up to 0.9 m during rainfall events. Falling stream water temperature at two types of time of concentration was negatively correlated with total precipitation and rising stream water level. Based on the relatively high value of regression and cumulative frequency distribution, the estimated rising stream water level was appropriate in small catchments (≤100 ha) when the stream water temperature decreased, and the stream water level increased during rainfall events. Rising stream water levels and falling stream water temperatures are responses to catchment-scale effects, which are influenced by the nature and rapidity of the hydrological responses. Therefore, the results of the present study indicate that spatial and temporal differences in thermal responses of stream water temperature to water levels were controlled by catchment-scale effects under rapidly changing rainfall.

In hot water: Interactions of temperature, nitrogen form and availability and photosynthetic and nitrogen uptake responses in natural Karenia brevis populations

During 2020–2021, an unusually prolonged bloom of the toxigenic dinoflagellate Karenia brevis persisted for more than 12 months along the Gulf coast of Florida, resulting in severe environmental effects. Motivated by the possibility that unusual nutrient conditions existed during summer 2021, the short-term interactions of temperature, nitrogen (N) forms (ammonium (NH4+), nitrate (NO3−), and urea) and availability on photosynthesis-irradiance responses and N uptake rates were examined in summer 2021 and compared to such responses from the earlier winter. Winter samples were exposed to temperatures of 15, 20, 25, 30 °C while summer samples were incubated at 15, 25, 30, 33 °C, representing the maximum range the cells might experience throughout the water column due to daytime surface heating or extreme weather events. Depending on thermal history of the cells, photosynthetic performance differed when cells were exposed to the same temperature, showing a capacity for thermal acclimation in this species. Although blooms generally do not persist throughout the summer, bloom biomass was remarkably higher in summer than during the winter. However, most of the photosynthetic parameters and N uptake rates, as well as total carbon (C) and N cell−1 were significantly lower in the summer populations, showing that the summer populations were photosynthetically and nutritionally stressed. When the summer cells were treated with urea, however, uptake rates and total C and N cell−1 were higher than with the other N substrates, especially in warmer waters, showing differential thermal responses depending on N forms.

Thermal adaptation of southern migrants to the district heating environment in the severe cold area, China: A longitudinally traced investigation

Preference for thermal environments is affected by the thermal histories on their own. A deeper understanding of human thermal adaptation to create comfortable and energy-saving environments is desired. To study the differences in thermal responses of southern migrants and northern locals to district heating environments, a longitudinally traced investigation was performed in the severe cold area, China. 74 freshmen with different thermal histories were invited for six weeks in winter. Physiological parameters and thermal response votes were collected. Results showed that the most significant difference in the thermal neutral temperature between locals and migrants reaches up to 1.1 °C, after acclimation, which decreases to 0.7 °C. Also, southern immigrants are not as sensitive to temperature changes as locals, but the gap is narrowing. Moreover, immigrants tended to wear lighter clothing at the same room temperature compared to natives, who were more flexible in adjusting their clothing. It was also observed that physiological and psychological adaptation processes were not synchronous. The humidity is the leading purpose of physiological discomfort for migrants. Physiological adaptation is a relatively slow process. It concluded that southern immigrants may take approximately 1 week to adapt to the thermal environment with district heating. However, they did not fully adapt to the humid environment until the 6th week. The findings have implications for understanding the mechanisms of thermal adaptation and creating comfortable built environments.

Characterization and Optimization of Cu-Al2O3 Nanocomposites Synthesized via High Energy Planetary Milling: A Morphological and Structural Study

This study examines the synthesis and characterization of a copper–alumina nanocomposite powder. Mechanical milling is employed to synthesize the powder, and a holistic analysis is conducted to evaluate its morphological and structural properties. TEM analysis reveals the presence of alumina particles within the copper matrix, indicating the formation of both coarse and fine particles at different stages of synthesis. XRD analysis demonstrates a reduction in copper’s crystallite size with increasing milling time, attributed to defects generated within the crystal lattice during milling. Additionally, statistical analysis is utilized to determine the significance of different factors influencing the synthesis process. ANOVA analysis reveals that milling time has a significant impact on the particle size of the nanocomposite powder, while temperature and their interaction do not exhibit significant effects. Optimization techniques are utilized to identify solutions that meet the specified constraints for milling time, temperature, particle size, and differential thermal response, resulting in favorable solutions within the desired ranges. The study highlights the efficacy of mechanical milling for producing nanocomposite powders with enhanced mechanical properties, offering promising prospects for advanced materials in various industries. Additionally, the characterization results provide valuable insights into the microstructure and phase distribution of the nanocomposite powder. The application of the Williamson–Hall method proves to be effective in determining the crystallite size of the synthesized powder.

Effects of body muscle and fat on differences in thermal preference

Although it has been shown that obese individuals have good cold tolerance due to the thermal insulation of the fat layer, some lean individuals also prefer cool environments. Here we systematically investigate the indicators of fat and muscle and consider their impacts on thermal preference. Combining the survey data on body mass index (BMI) and exercise, and the experimental data on tissue thicknesses, thermal sensation, thermal comfort, and skin temperature, we show that high fat or high muscle correlates positively with cool preference. In contrast, low fat or low muscle correlates with warm preference. Furthermore, participants of the same body size, one group of high muscle content (HM group) and another group of low muscle content (LM group), are enrolled in a thermal response experiment. Our results suggest that the HM group can accept lower temperatures than the LM group. The results can be used to explain the differences in thermal responses of occupants in the same environment.

Comparative proteomic and phosphoproteomic analysis reveals differential heat response mechanism in two congeneric oyster species

High-temperature stress caused by global climate change poses a significant threat to marine ectotherms. This study investigated the role of protein phosphorylation modifications in the molecular regulation network under heat stress in oysters, which are representative intertidal organisms that experience considerable temperature changes. Firstly, the study compared the extent of thermal damage between two congeneric oyster species, the relative heat-tolerant Crassostrea angulata (C. angulata) and heat-sensitive Crassostrea gigas (C. gigas), under sublethal temperature (37 °C) for 12 h, using various physiological and biochemical methods. Subsequently, the comparative proteomic and phosphoproteomic analyses revealed that high-temperature considerably regulated signal transduction, energy metabolism, protein synthesis, cell survival and apoptosis, and cytoskeleton remodeling through phosphorylation modifications of related receptors and kinases. Furthermore, the protein kinase A, mitogen-activated protein kinase 1, tyrosine-protein kinase Src, and serine/threonine kinase AKT, exhibiting differential phosphorylation modification patterns, were identified as hub regulators that may enhance glycolysis and TCA cycle to increase the energy supply, distribute protein synthesis, inhibit Caspase-dependent apoptosis activated by endogenous mitochondrial cytochrome release and maintain cytoskeletal stability, ultimately shaping the higher thermal resistance of C. angulata. This study represents the first investigation of protein phosphorylation dynamics in marine invertebrates under heat stress, reveals the molecular mechanisms underlying the differential thermal responses between two Crassostrea oysters at the phosphorylation level, and provides new insights into understanding phosphorylation-mediated molecular responses in marine organisms during environmental changes and predicting the adaptive potential in the context of global warming.

Quantitative Evaluation of the Fracturing State of Crystalline Rocks Using Infrared Thermography

The fracturing state of rocks is a fundamental control on their hydro-mechanical properties. It can be quantified in the laboratory by non-destructive geophysical techniques that are hardly applicable in situ, where biased mapping and statistical sampling strategies are usually exploited. We explore the suitabilty of infrared thermography (IRT) to develop a quantitative, physics-based approach to predict rock fracturing starting from laboratory scales and conditions. To this aim, we performed an experimental study on the cooling behaviour of pre-fractured gneiss and mica schist samples, whose 3D fracture networks were reconstructed using Micro-CT and quantified by unbiased fracture abundance measures. We carried out cooling experiments in both controlled (laboratory) and natural (outdoor) environmental conditions and monitored temperature with a thermal camera. We extracted multi-temporal thermograms to reconstruct the spatial patterns and time histories of temperature during cooling. Their synthetic description show statistically significant correlations with fracture abundance measures. More intensely fractured rocks cool at faster rates and outdoor experiments show that differences in thermal response can be detected even in natural environmental conditions. 3D FEM models reproducing laboratory experiments outline the fundamental control of fracture pattern and convective boundary conditions on cooling dynamics. Based on a lumped capacitance approach, we provided a synthetic description of cooling curves in terms of a Curve Shape Parameter, independent on absolute thermal boundary conditions and lithology. This provides a starting point toward the development of a quantitative methodology for the contactless in situ assessment of rock mass fracturing.

High-Resolution Monitoring of Scour Using a Novel Fiber-Optic Distributed Temperature Sensing Device: A Proof-of-Concept Laboratory Study.

Scour events can severely change the characteristics of streams and impose detrimental hazards on any structures built on them. The development of robust and accurate devices to monitor scour is therefore essential for studying and developing mitigation strategies for these adverse consequences. This technical note introduces a novel scour-monitoring device that utilizes new advances in the fiber-optic distributed temperature sensing (FO-DTS) technology. The novel FO-DTS scour-monitoring device utilizes the differential thermal responses of sediment, water, and air media to a heating event to accurately identify the locations of the interfaces between them. The performance of the device was tested in a laboratory flume under flow conditions with water velocities ranging from 0 m/s to 0.16 m/s. In addition, the effect of the measurement duration on the device's measurement accuracy was also investigated. The FO-DTS scour-monitoring device managed to detect the sediment-water and water-air interfaces with average absolute errors of 1.60 cm and 0.63 cm, respectively. A measurement duration of fewer than 238 s was sufficient to obtain stable measurements of the locations of the sediment-water and water-air interfaces for all the tested flow conditions.

Experimental study on the effects of exercise intensity and thermal environment on thermal responses

Public exercise facilities have recently emerged across China. This study aims to investigate the impacts of exercise intensity and thermal environment on thermal responses as well as examine the dynamic changes and differences in thermal responses during exercise. Using a controlled thermal chamber, university students were assessed at varying walking speeds under six thermal conditions, from −15 to 35 °C. Their psychological and physiological responses were observed and recorded in real time during the thermal adaption, exercise, and rest phase. Firstly, the exercise intensity significantly affected heart rate and metabolic rate, whereas the thermal environment had no significant effect. The effect of the thermal environment on skin temperature, thermal sensation vote (TSV), and thermal comfort vote (TCV) was more pronounced than that of exercise intensity. Secondly, during exercise, the metabolic rate took 6–9 min to stabilise, and the psychological response lagged compared to the physiological response. Thermal sensation was closest to neutral at 15 °C, 5 °C, and −5 °C when walking at 3 km/h, 4.50 km/h, and 6 km/h, respectively. Thermal comfort vote (TCV) levels were greater for higher exercise intensities at −15 to 5 °C, lower for higher exercise intensities at 25–35 °C, and similar for varied exercise intensities at 15 °C. Finally, current thermal comfort guidelines underestimate the exercise metabolic rate by at least 9.7%. This study helps clarify the dynamic changes and influence factors of thermal responses during exercise and provides a reference for future research on exercisers’ thermal responses.

Highly conserved thermal performance strategies may limit adaptive potential in corals.

Increasing seawater temperatures are expected to have profound consequences for reef-building corals' physiology. Understanding how demography changes in response to chronic exposure to warming will help forecast how coral communities will respond to climate change. Here, we measure growth rates of coral fragments of four common species, while exposing them to temperatures ranging from 19°C to 31°C for one month to calibrate their thermal-performance curves (TPCs). Our results show that, while there are contrasting differences between species, the shape of the TPCs was remarkably consistent among individuals of the same species. The low variation in thermal sensitivity within species may imply a reduced capacity for rapid adaptive responses to future changes in thermal regimes. Additionally, interspecific differences in thermal responses show a negative relationship between maximum growth and thermal optima, contradicting expectations derived from the classic 'warmer-is-better' hypothesis. Among species, there was a trade-off between current and future growth, whereby most species perform well under current thermal regimes but are susceptible to future increases in temperature. Increases in water temperature with climate change are likely to reduce growth rates, further hampering future coral reef recovery rates and potentially altering community composition.

Influence of Butanol Isomerization on Photothermal Hydrogen Production over Ti@TiO2 Core-Shell Nanoparticles

In this work, we reported for the first time the effect of butanol isomerization on the photothermal production of hydrogen in the presence of a noble, metal-free Ti@TiO2 core-shell photocatalyst. The experiments were performed in aqueous solutions of 1-BuOH, 2-BuOH, and t-BuOH under Xe lamp irradiation (vis/NIR: 8.4 W, UV: 0.6 W) at 35–69 °C. The increase in temperature significantly enhanced H2 formation, indicating a strong photothermal effect in the studied systems. However, in dark conditions, H2 emission was not observed even at elevated temperatures, which clearly points out the photonic origin of H2 photothermal formation. The rate of H2 production followed the order of 1-BuOH &gt;&gt; 2-BuOH &gt; t-BuOH in the entire range of studied temperatures. In the systems with 1-BuOH and 2-BuOH, hydrogen was the only gaseous product measured online in the outlet carrier argon using mass spectrometry. By contrast, a mixture of H2, CH4, and C2H6 was detected for t-BuOH, indicating a C–C bond scission with this isomer during photocatalytic degradation. The apparent activation energies, Ea, with 1-BuOH/2-BuOH isomers (20–21 kJ·mol−1) was found to be larger than for t-BuOH (13 kJ·mol−1). The significant difference in thermal response for 1-BuOH/2-BuOH and t-BuOH isomers was ascribed to the difference in the photocatalytic mechanisms of these species. The photothermal effect with 1-BuOH/2-BuOH isomers can be explained by the thermally induced transfer of photogenerated, shallowly trapped electron holes to highly reactive free holes at the surface of TiO2 and the further hole-mediated cleavage of the O-H bond. In the system with t-BuOH, another mechanism could also contribute to the overall process through hydrogen abstraction from the C–H bond by an intermediate •OH radical, leading to CH3• group ejection. Formation of •OH radicals during light irradiation of Ti@TiO2 nanoparticle suspension in water has been confirmed using terephthalate dosimetry. This analysis also revealed a positive temperature response of •OH radical formation.