Climate-controlled Chamber Research Articles

Exploring the impact of clothing insulation on thermal comfort evaluation using thermal manikins

Thermal manikins are valuable tools used in advancing our understanding of thermal comfort. This study examines the effect of varying clothing insulation on the predicted degree of thermal comfort using a thermal manikin named MONICA (MONitoring Indoor Comfort and Air quality). The experiments were conducted in a controlled climate chamber with the room temperature maintained at 24 °C. Three different clothing configurations were tested: naked, summer clothes (0.2 clo), and winter office clothes (0.7 clo). The equivalent temperature was measured for each configuration and compared to the Predicted Mean Vote (PMV) values obtained simultaneously. Additionally, the study utilized the Background Oriented Schlieren (BOS) technique to visualize the thermally driven airflow around the manikin. The findings from this study confirm the effectiveness of the thermal manikin in simulating human thermal responses and provide valuable insights into the role of clothing insulation in thermal comfort assessments. The obtained results will be useful for choosing the right clothing insulation for future thermal comfort assessments with the manikin.

Effects of combinations of the essential oils trans-anethole, thymol and carvacrol against larvae of the screwworm fly Cochliomyia hominivorax in vitro.

This study investigated the combined effect of trans-anethole, carvacrol and thymol on third-instar larvae of C. hominivorax. For this experiment, third-stage larvae of C. hominivorax were removed from a laboratory colony to perform an in vitro bioassay. The three volatile compounds used in this study, trans-anethole, carvacrol and thymol. Different dilutions of these volatile compounds were performed with the diluent acetone (99.5 %) to determine the associative effect (synergism, addition or antagonism). Three concentrations below the estimated LC50 were prepared (10, 20 and 100 μg.cm-2). These compounds were impregnated in filter paper discs, which were dried and transferred to Petri dishes. Ten larvae were added to each dish and incubated in climate-controlled chambers at 28 ± 1 ºC and 75 ± 10 % relative humidity for 24 and 48 hours. Mortality was assessed based on the absence or change in larval movement, as observed under a stereomicroscope. After 24 hours, trans-anethole (A) caused mortality rates in the range of 23-33.5 %, carvacrol (C) of 9-59 % and thymol (T) of 27-81.5 %, in the three concentrations evaluated. The combination of trans-anethole with carvacrol resulted in mortality rates between 11 % and 50 %, demonstrating antagonistic action. The combination of trans-anethole with thymol caused mortality of 12.5-55.5 %, and the combination of carvacrol with thymol generated mortality of 75.5-99.5 %, indicating synergism. After 48 hours, (A) produced a mortality range of 29-49 %, (C) of 10.5-63 %, and (T) of 37.5-86 % in the three concentrations, maintaining the same relationship of antagonistic and synergistic activity. The combination of trans-anethole with carvacrol resulted in mortality rates between 16 % and 56.5 %, while the combination of trans-anethole with thymol caused mortality of 27.5-62.5 % and the combination of carvacrol with thymol presented mortality between 83 % and 99.5 %. Hence, there was an antagonistic effect when trans-anethole was associated with carvacrol and thymol and a dose-dependent synergistic effect when carvacrol was associated with thymol against third instar larvae of C. hominivorax.

Thermal dynamics of textile fibers: enhancing outdoor comfort through exothermic and endothermic interactions

This study explores the thermal effects of various fibers in outdoor sportswear, analyzing how their exothermic and endothermic responses influence wearer comfort in changing environmental conditions. Using a sweating thermal manikin in a controlled climate chamber, we simulated outdoor activities in windy and non-windy scenarios at 15 °C and 50% relative humidity in two and a half hours in three phases imitating rest-activity-cool down conditions. Our investigation focused on the skin microclimate, fabric temperature, and mean skin temperature with garments made from 100% wool, 100% polyester, 100% viscose, and 100% cotton. Key findings indicate that wool fibers, due to their heat release upon moisture absorption (approximately 2 °C after moisture absorption), significantly enhance thermal stability and reduce post-exercise chill by maintaining a balanced skin microclimate (about 50% less drying rate). The study highlights the importance of considering dynamic, transient conditions in sportswear design, providing insights for the development of more comfortable and thermally efficient clothing for outdoor activities.

Beat the heat: wearable-based study of perceived heat stress and physiological strain in swiss track workers in a controlled climate chamber

Increasing temperatures pose new challenges for track workers (TWs), who endure prolonged exposure to extreme heat and humidity. New methods are critically needed to assess their performance and heat tolerance, aiming to mitigate workplace accidents and long-term health consequences. This study aimed to investigate the physiological effects of heat exposure on TWs, using wearable sensors to monitor key physiological parameters under controlled environmental conditions. Nineteen TWs participated in the study, which included two experimental sessions simulating different thermal environments: a typical Swiss summer night and a hot summer day. Participants' core body temperature, heart rate (HR), and skin temperature were monitored using wearable sensors, and physiological indexes were computed. In addition, perceptual strain index (PeSI) and psychomotor vigilance task (PVT) response times were recorded. Statistically significant increases in physiological parameters were observed under hotter conditions. The study identified statistically significant correlations between the PeSI and the physiological strain index and between PeSI and HR. Perceptual scores were consistently higher than the values derived from physiological measurements, suggesting a greater subjective experience of heat strain. The PVT response times were higher on the hotter day, reflecting increased cognitive strain due to heat exposure. The study highlights the critical impact of heat stress on TWs, with statistically significant increases in physiological and cognitive strain under higher temperatures. Future research should focus on real-world applications of heat strain monitoring.

Survival of Salmonella on Biodegradable Mulch, Landscape Fabric, and Plastic Mulch.

Ground covers areused inproduce production to enhance plant growth and control diseases and pests. While various factors are considered when selecting commercial ground covers, food safety, particularly the survival of foodborne pathogens, is often overlooked. This study aimed to assess the survival ofSalmonellaon different ground covers, including biodegradable mulch, landscape fabric, and plastic mulch. New rolls of each ground cover were cut to fit a 100 x 15 mm petri dish and spot inoculated with a seven-strainSalmonellacocktail at approximately 6 log CFU/cm2. The inoculated coupons were stored in a climate-controlled chamber (23°C, 55% relative humidity) and sampled at 0, 0.06 (1.5 h), 0.17 (4 h), 1, 2, 3, 5, 7, 30, 60, 90, and 140 days post-inoculation (dpi). If counts dropped below the detection limit (<0.12 log CFU/cm2), enrichments were performed following the Food and Drug Administration's Bacteriological Analytical ManualSalmonellaprotocol.Salmonella survived 140 dpi on all tested ground covers, with reductions >5 log CFU/cm2. Survival rates at 140 dpi were highest on landscape fabric (83%, 25/30) followed by plastic mulch (50%, 15/30) and biodegradable mulch (13%, 4/30) coupons (p<0.05). During the first 30 dpi, biodegradable mulch exhibited the smallest reduction inSalmonella(2.47±0.26 log CFU/cm2), compared to landscape fabric (3.07±0.30 log CFU/cm2) and plastic mulch (3.86±0.72 log CFU/cm2). After 60 dpi,Salmonellareductions stabilized across all materials (∼4 log CFU/cm2) and by 90 dpi, no significant differences were observed between ground cover types (p>0.05). AlthoughSalmonellasurvival varied among ground covers in the short-term (0-30 dpi), a >5 log CFU/cm2reduction ofSalmonellawas observed amongst all materials by 140 dpi.Findings suggest that ground cover material influencesSalmonellasurvival and should be factored into food safety risk management strategies, especially when ground covers are reused.

Photosynthetic efficiency and water retention in okra (Abelmoschus esculentus) contribute to tolerance to single and combined effects of drought and heat stress

The co-occurrence of drought and heat significantly hampers plant productivity. Although their impacts are well studied, these studies have been based on the effects of individual stressors rather than their combined influence. Okra is crucial for food and nutritional security and livelihoods in many regions, yet it remains under-researched and unimproved. Okra has been proven to be sensitive to both drought and heat stress. This study employed a cost-effective phenotyping method to assess key traits characterising the diversity of okra morphophysiological responses to independent and interactive heat-drought stresses. This study aimed to understand okra responses to stress, identify stress-resilient traits, and characterise okra genotypes. We also addressed the need to examine interactive stress effects, which mirror real-world scenarios more accurately than single-stress studies. Sixty-three okra genotypes were subjected to heat, drought, or concurrent heat-drought stress at the seedling stage in improvised climate-controlled chambers. The germplasm exhibited significant variations in response to the various stresses. The broad-sense heritability was high (> 0.60) for traits such as chlorophyll content, plant biomass, performance indices, electrolyte leakage, and total leaf area. Drought stress alone had a more pronounced effect than heat stress alone, and the adverse impact was worsened under combined heat and drought stress. The interactive impact of drought and heat was more likely additive than antagonistic or synergistic. A positive and strong relationship was observed between photosynthetic efficiency parameters such as the Fv/Fm ratio, chlorophyll content, relative water index, and biomass parameters such as dry shoot weight. The 63 okra genotypes were classified into three distinct clusters, suggesting potential for future breeding efforts. Okra genotype considered to be tolerant or climate resilient (such as GH170, V1060831, GH174, V1060874, and GH106) to drought and heat, maintained enhanced photosynthetic efficiency and high internal water potential, possibly reducing osmotic and oxidative damage. This study revealed some mechanisms underlying the adaptation of okra genotypes to independent and combined heat and drought stress. The results provide a basis for breeding efforts to develop climate-resilient okra varieties.

Role of silicon in legume‐insect interactions: Insights from a plant experiencing different levels of herbivory

Abstract Silicon (Si) supplementation can enhance symbiotic functions in some legumes (Fabaceae) with their nitrogen‐fixing rhizobia, such as root nodulation and nitrogen fixation. However, it is still poorly understood how Si influences legume–insect interactions. Here, we investigated how a symbiotic legume responds not only to Si supplementation but also to herbivory treatment with varying infestation levels in two events. We conducted a controlled climate chamber experiment by growing Medicago truncatula plants inoculated with rhizobia. For half of the plants, the soil was kept without Si (−Si), whereas the other half was regularly supplemented with Si (+Si). We then infested the plants with caterpillars of Spodoptera littoralis with 0, 1 or 3 larvae and 0, 1 or 1 larva in single herbivory attack and in double herbivory attack, respectively. To understand plant responses to such treatment combinations, we examined 16 functional traits. Nodule number, nodule fresh mass and nodule leghaemoglobin concentrations were not affected in single attack plants. However, increasing levels of herbivory led to decreases in such measured traits in double attack plants. Foliar C to N ratio increased in single attack plants but decreased in double attack plants with increasing levels of herbivory, indicating contrasting resource allocation. Herbivory did not affect the content of foliar Si, which was higher in +Si than −Si plants. Si and herbivory led to reduced foliar phenolics in double attack plants, suggesting a potential trade‐off between silicification and phenolic production. Si and herbivory led to increased trichome densities in single attack plants, but patterns were less clear in double attack plants. Herbivory but not Si reduced plant biomass with increasing levels of herbivory in double attack plants. Relative growth rates of the caterpillars, as proxy for plant resistance, decreased mainly due to herbivory treatment, when fed on single attack plants. Using a trait‐based approach, we provide novel insights to better understand the response of a legume to Si supplementation and different herbivory levels and events. We conclude that herbivory predominantly exerts much stronger effects than Si on various plant traits, pointing to a necessity to respond to herbivory by induced defence strategies. Read the free Plain Language Summary for this article on the Journal blog.

Mitigating the Adverse Effects of Salt Stress on Pepper Plants Through Arbuscular Mycorrhizal Fungi (AMF) and Beneficial Bacterial (PGPR) Inoculation

This study investigates arbuscular mycorrhizal fungi (AMF), plant growth-promoting rhizobacteria (PGPR), and their combined application under salt stress (200 mM NaCl), emphasizing their synergistic potential to enhance plant resilience. Conducted in a controlled climate chamber, key parameters such as plant height, biomass, SPAD values, ion leakage, relative water content (RWC), osmotic potential, and mineral uptake were assessed. Salt stress significantly reduced plant growth, chlorophyll content, and nutrient absorption. However, AMF and PGPR improved plant performance, with co-inoculation showing the highest efficacy in increasing RWC, nutrient uptake, and maintaining membrane stability. AMF and PGPR treatments enhanced potassium retention and reduced sodium and chloride accumulation, mitigating ionic imbalances. The improved chlorophyll content and water relations under co-inoculation demonstrate the potential of these biostimulants to boost photosynthesis and plant resilience. These findings highlight AMF and PGPR as eco-friendly solutions for sustainable agriculture, promoting crop productivity and stress tolerance under saline conditions.

Quantifying human thermal adaptation for indoor environments through field surveys and climate chamber experiments

ABSTRACT Thermal comfort boundaries established through climate chamber experiments are often found to significantly vary in real-world conditions based on the potential for thermal adaptation. In this context, this research aims to quantify the extent of thermal adaptation using a personalized ventilation system. We hypothesize that a personalized ventilation system can enhance thermal adaptation compared to real-world settings with limited opportunity for thermal adaptation. The study is based on thermal comfort surveys in mixed-mode open-plan office spaces of a humid subtropical region (Cwa), and a controlled climate chamber with a provision for personalized ventilation. We obtained 5629 subjective thermal responses through longitudinal field surveys accompanied by environmental measurements. In a climate chamber, 16 acclimatized volunteers were subjected to 140 different set-points with air temperature (Ta), relative humidity (RH), and air velocity (Va) variations yielding 19,200 subjective responses. A thermo-neutral temperature (Tn) of 26.5°C with an acceptability band of ±5.9°C was obtained through the field surveys. The Tn obtained from climate chamber surveys varied from 28.0°C to 29.3°C with an acceptability band of ±3.6°C depending on the ventilation rate. An empirical relationship between thermal sensation vote (TSV) and multiple environmental variables (Calidity) suggests 2°C higher Tn for Caliditychamber, Thermal adaptation correction factor of 2.1°C for warm-dry indoor environment and 1°C for warm-humid indoor environment were deduced through comparative analysis.

The efficiency of portable air cleaners in reducing cross-exposure through respiratory aerosols: Effects of flowrate, location, and unit type

This study evaluates the efficacy of portable air cleaners (PACs) in a controlled climate chamber that simulates an office environment, assessing their impact on respiratory particle transmission between two thermal manikins (representing an infected and an exposed individual) as well as on the noise level in the chamber. The study explores three types of PAC, namely floor-type (PAC1), table (PAC2) and personalized (PAC3) in various locations and operation modes. The particles were generated using an aerosol generator and introduced into the infected manikin's exhalation; the particle concentration at the exposed manikin's breathing zone (BZ) was measured using an aerodynamic particle sizer. The results showed that the PAC2, operating at a flow rate of 97 m³/h, significantly reduced the intake fraction (IF) by over 90 % within the first hour, proving to be the most effective in minimizing cross-exposure risks while maintaining sound levels within the acceptable limits for office rooms. In contrast, PAC3, with a lower flow rate of 13 m³/h, reduced IF by only 21.6 % after 60 min. The result also showed that settings with higher flow rates (higher than 134 m3/h) resulted in noise levels above the maximum allowable for office spaces for all tested PACs. Additionally, prolonged operation did not further decrease IF significantly after reaching optimal reduction levels within 30–60 min, depending on the PAC type and settings. Further, the study showed that strategic placement away from direct alignment with occupants' BZ is recommended to optimize aerosol removal and noise management.

Short duration heatwaves increase body temperature and alter blood gas balance but may not cause oxidative stress and intestinal structure variations in lambs

This study investigated the impact of short duration heatwaves (HW) on the body temperature, blood gas, intestinal histology, and oxidative stress parameters of second cross lambs. Seventy-two second cross lambs [Poll Dorset × (Border Leicester × Merino)] were selected and exposed to either one, three or five days HW (28–38°C and 40–60 % relative humidity (RH)) or thermoneutral (TN; 18–21°C, 40–55 % RH) conditions in climate-controlled chambers. Lambs exposed to one to five days HW exhibited higher face, eye and ear temperature compared to animals exposed to equal duration under TN conditions. HW also had a significant impact on blood gas parameters which include higher blood pH, and lower CO2, Ca2+, Na+, CHCO3- and Cl-. However, HW lambs’ histology structure of the ileum and the GSSG: GSH of the ileum and Longissimus thoracis (LT) muscle were not influenced (P > 0.05) by HW. LT muscle showed higher total antioxidant capacity (TAC) in HW conditions, but the TAC of intestine and blood had no difference between HW and TN groups. These results suggest that short-duration HW (one to five days) had a significant impact on lambs’ body temperature and blood parameters, but neither caused oxidative stress nor any changes in their intestinal structure.

Preserving Cultural Heritage: Enhancing Limestone Durability with Nano-TiO2 Coating

External and internal microclimatic conditions, biodeterioration, anthropogenic factors, etc, influence the natural stone support for artifacts and built heritage. Based on this fact, the present study explores the effectiveness of nano-TiO2 in preserving and enhancing the durability of natural stone used in the façades of heritage buildings, focusing on the Markovits-Mathéser House in Oradea Municipality, Romania. The investigation involved treating rock samples (fossiliferous limestone) with 2% and 5% nano-TiO2 solutions and subjecting them to simulated extreme climatic conditions for the analyzed area in a controlled climatic chamber for six months. The treated samples demonstrated a significantly higher compressive strength than untreated benchmarks. SEM analyses confirmed that nano-TiO2 formed a protective layer, filling micro-cracks and pores, thereby enhancing the stone’s resistance to environmental stressors. The study also found that the nanoparticle coating maintained its integrity under extreme temperature and humidity variations, with only a slight decrease in surface coverage. These findings suggest that nano-TiO2 coatings significantly improve heritage building materials’ mechanical properties and longevity. However, the study highlights the importance of careful application and long-term evaluation to ensure environmental and health safety. Overall, nano-TiO2 presents a promising solution for the conservation of cultural heritage, offering enhanced durability and protection against climatic and environmental challenges. Further research is recommended to optimize application workflow and formulations for broader and more effective use in heritage conservation.

Evaluation of the Biostimulant Activity and Verticillium Wilt Protection of an Onion Extract in Olive Crops (Olea europaea).

The olive tree is crucial to the Mediterranean agricultural economy but faces significant threats from climate change and soil-borne pathogens like Verticillium dahliae. This study assesses the dual role of an onion extract formulation, rich in organosulfur compounds, as both biostimulant and antifungal agent. Research was conducted across three settings: a controlled climatic chamber with non-stressed olive trees; an experimental farm with olive trees under abiotic stress; and two commercial olive orchards affected by V. dahliae. Results showed that in the climatic chamber, onion extract significantly reduced MDA levels in olive leaves, with a more pronounced reduction observed when the extract was applied by irrigation compared to foliar spray. The treatment also increased root length by up to 37.1% compared to controls. In field trials, irrigation with onion extract increased the number of new shoots by 148% and the length of shoots by 53.5%. In commercial orchards, treated trees exhibited reduced MDA levels, lower V. dahliae density, and a 26.7% increase in fruit fat content. These findings suggest that the onion extract effectively reduces oxidative stress and pathogen colonization, while enhancing plant development and fruit fat content. This supports the use of the onion extract formulation as a promising, sustainable alternative to chemical treatments for improving olive crop resilience.

Impact of Ultraviolet-C Exposure and Mechanical Stress on Conidium Production in Corynespora cassiicola Isolates From Cotton and Soybean

The procurement of inoculum for bioassays with target spot, a significant disease in cotton and soybeans, caused by Corynespora cassiicola can be hindered by the low production of conidia on artificial culture media. The study aimed to determine whether mechanical stress on the mycelium and exposure to ultraviolet-C (UV-C) radiation for varying durations could enhance conidial production in C. cassiicola isolates. Eight isolates from cotton and soy were used, grown in V8 juice medium. After five days of incubation in a climate-controlled chamber, each isolate either underwent mycelium scraping or remained unscraped and was subsequently exposed to UV-C radiation for either 1.0, 1.5 or 2.0 min, in comparison to a control group with zero UV exposure time. Following these procedures, conidial suspensions from each isolate were obtained and quantified (conidia per mL) using a Neubauer chamber The ISO 3S and ISO 4S isolates were found to produce more conidia than the other isolates, regardless of whether they were subjected to mycelium scraping or exposure to UV-C radiation. For most isolates, exposure to UV-C radiation for 1.0-1.5 min led to increased conidium production. Generally, it was not feasible to discern differences in conidial production with respect to the mycelium scraping process. Nevertheless, exposure to UV-C radiation for 1.0 min can be used to induce conidium production in C. cassiicola isolates.

Using Thermal Signature to Evaluate Heat Stress Levels in Laying Hens with a Machine-Learning-Based Classifier.

Infrared thermography has been investigated in recent studies to monitor body surface temperature and correlate it with animal welfare and performance factors. In this context, this study proposes the use of the thermal signature method as a feature extractor from the temperature matrix obtained from regions of the body surface of laying hens (face, eye, wattle, comb, leg, and foot) to enable the construction of a computational model for heat stress level classification. In an experiment conducted in climate-controlled chambers, 192 laying hens, 34 weeks old, from two different strains (Dekalb White and Dekalb Brown) were divided into groups and housed under conditions of heat stress (35 °C and 60% humidity) and thermal comfort (26 °C and 60% humidity). Weekly, individual thermal images of the hens were collected using a thermographic camera, along with their respective rectal temperatures. Surface temperatures of the six featherless image areas of the hens' bodies were cut out. Rectal temperature was used to label each infrared thermography data as "Danger" or "Normal", and five different classifier models (Random Forest, Random Tree, Multilayer Perceptron, K-Nearest Neighbors, and Logistic Regression) for rectal temperature class were generated using the respective thermal signatures. No differences between the strains were observed in the thermal signature of surface temperature and rectal temperature. It was evidenced that the rectal temperature and the thermal signature express heat stress and comfort conditions. The Random Forest model for the face area of the laying hen achieved the highest performance (89.0%). For the wattle area, a Random Forest model also demonstrated high performance (88.3%), indicating the significance of this area in strains where it is more developed. These findings validate the method of extracting characteristics from infrared thermography. When combined with machine learning, this method has proven promising for generating classifier models of thermal stress levels in laying hen production environments.

Effects of wearing medical gowns at different temperatures on the physiological responses of female healthcare workers during the COVID-19 pandemic.

Using medical gowns with high protection against COVID-19 among healthcare workers (HCWs) may limit heat exchange, resulting in physiological challenges. This study aimed to compare the physiological and neurophysiological responses of female HCWs when using two typical medical gowns at different temperatures during the COVID-19 pandemic. Twenty healthy female HCWs participated in this study. Participants wore two types of medical gowns: Spunbond gown (SG) and laminate gown (LG). They walked on a treadmill in a controlled climate chamber for 30 minutes at three different temperatures (24, 28, and 32°C). Heart rate (HR), skin surface temperature (ST), clothing surface temperature (CT), ear temperature (ET), blood oxygen percentage (SaO2), galvanic skin response (GSR), and blood pressure were measured before and after walking on a treadmill. The study's results were analyzed using SPSS26. The study found that LG led to an average increase of 0.575°C in CT compared to SG at the same temperatures (P < 0.03). The average HR increased by 6.5 bpm in LG at 28°C compared to SG at a comfortable temperature (P = 0.01). The average ET in SG and GSR in LG at 32°C increased by 0.39°C and 0.25μS, respectively, compared to the comfortable temperature (P < 0.02). The study recommends maintaining a comfortable temperature range in hospitals to prevent physiological challenges among HCWs wearing medical gowns with high protection against COVID-19. This is important because using LG, compared to SG, at high temperatures can increase HR, ET, CT, and GSR.

Effect of seven days heat stress on feed and water intake, milk characteristics, blood parameters, physiological indicators, and gene expression in Holstein dairy cows

This study examined the effects of 7 days of heat stress on eight early lactating Holstein cows in climate-controlled chambers. The early lactating Holstein cows (42 ± 2 days in milk, 29.27 ± 0.38 kg/day milk yield, 1.21 ± 0.05 parity) were subjected to two 14-day periods, each consisting of 7 days of adaptation and 7 days of heat stress. Conditions were set to 22 °C and 50% humidity during adaptation, followed by heat stress periods with low-temperature, low-humidity (LTLH, 71 THI) and high-temperature, high-humidity (HTHH, 86 THI) treatments. Data from the last 7 days were analyzed using a mixed procedure in SAS. In the study, the HTHH group displayed marked physiological and biochemical changes on 14 days of heat stress exposure compared to the LTLH group. Firstly, the HTHH group's dry matter intake decreased by approximately 12% while their water intake increased by about 23%. Secondly, both milk yield and milk protein production in the HTHH group decreased by 10% and 20%, respectively. Thirdly, there was a reduction in white blood cells, hemoglobin, mean corpuscular hemoglobin, and platelets in the HTHH group, with concurrent increases in glucose, non-esterified fatty acids, and albumin concentrations. Additionally, the HTHH group exhibited elevated plasma concentrations of cortisol and haptoglobin. Moreover, the gene expression of heat shock protein 70 and heat shock protein 90 was significantly upregulated in the HTHH group's peripheral blood mononuclear cells. Lastly, key physiological indicators such as rectal temperature, heart rate, and skin temperature showed substantial elevations in the HTHH group. Considering the enormous negative effects observed in the analyzed blood metabolites, milk yield and compositions, and heat shock protein gene expression, early lactating Holstein cows were found to be more vulnerable to HTHH than LTLH over a 7 days exposure to heat stress.

Effects of the nitrification inhibitor nitrapyrin on N2O emissions under elevated CO2 and rising temperature in a wheat cropping system

Nitrogen (N) fertilizer input will likely increase to meet the food demands of a growing population under climate change conditions, characterized by increasing atmospheric CO2 concentration and temperature. Nitrification inhibitors have the potential to reduce N2O emissions from N fertilized croplands. However, it remains unclear whether future climate change scenarios could affect the effectiveness of nitrification inhibitors. In a two-year study, winter wheat (Triticum aestivum L.) was cultivated in climate-controlled growth chambers with an elevated CO2 concentration (ambient +200 μmol mol−1) and increased temperature (ambient +2 °C). Urea was applied with or without nitrapyrin (0.5 % of urea-N). In this study, we measured nitrous oxide (N2O) fluxes, soil ammonium and nitrate levels, and the abundance of five nitrogen-cycling genes related to nitrification (amoA of ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA)) and denitrification (nirS, nirK and nosZ). Key findings included the following: 1) without nitrapyrin, cumulative N2O emissions were not significantly altered by increased temperature, but decreased 24.9 % by the combination of elevated CO2 and temperature treatment and 17.5 % by the elevated CO2 alone. NO3−-N accumulation occurred in soils under increased CO2 and temperature, both individual and in combination; 2) nitrapyrin effectively reduced AOB abundance, inhibiting NO3−-N accumulation and N2O emission, irrespective of CO2 concentrations and temperature. However, under the combination of elevated CO2 and temperature conditions, the efficiency of nitrapyrin in reducing N2O emission was lower (−13 % to −49 %) than that in the control (−28 % to −65 %) and elevated CO2 (−32 % to −71 %) conditions. This reduced effectiveness of the combined treatment can be attributed to the inability of nitrapyrin to inhibit the AOA, nirS and nirK genes. Thus, nitrapyrin is expected to reduce N2O emissions under future climate change scenarios, but the efficacy may be lower than previously expected when CO2 concentration and temperature increase simultaneously. The indirect effects of nitrapyrin on denitrifiers under climate change scenarios should be considered in future research.

Nanocluster Aerosols from Ozone-Human Chemistry Are Dominated by Squalene-Ozone Reactions.

Nanocluster aerosols (NCAs, <3 nm particles) are associated with climate feedbacks and potentially with human health. Our recent study revealed NCA formation owing to the reaction of ozone with human surfaces. However, the underlying mechanisms driving NCA emissions remain unexplored. Squalene is the most abundant compound in human skin lipids that reacts with ozone, followed by unsaturated fatty acids. This study aims to examine the contribution of the squalene-ozone reaction to NCA formation and the influence of ozone and ammonia (NH3) levels. In a climate-controlled chamber, we painted squalene and 6-hexadecenoic acid (C16:1n6) on glass plates to facilitate their reactions with ozone. The squalene-ozone reaction was further investigated at different ozone levels (15 and 90 ppb) and NH3 levels (0 and 375 ppb). The results demonstrate that the ozonolysis of human skin lipid compounds contributes to NCA formation. With a typical squalene-C16:1n6 ratio found in human skin lipids (4:1), squalene generated 40 times more NCAs than did C16:1n6 and, thus, dominated NCA formation. More NCAs were generated with increased ozone levels, whereas increased NH3 levels were associated with the stronger generation of larger NCAs but fewer of the smallest ones. This study experimentally confirms that NCAs are primarily formed from squalene-ozone reactions in ozone-human chemistry.

Jasmonic acid and heat stress induce high volatile organic compound emissions in Picea abies from needles, but not from roots.

Plants emit diverse volatile organic compounds (VOCs) from their leaves and roots for protection against biotic and abiotic stress. An important signaling cascade activated by aboveground herbivory is the jasmonic acid (JA) pathway that stimulates the production of VOCs. So far it remains unclear if the activation of this pathway also leads to enhanced VOC emissions from conifer roots, and how the interplay of above- and belowground defenses in plants are affected by multiple stressors. Therefore, we simultaneously analyzed needle and root VOC emissions of Picea abies saplings, as well as CO2 and H2O fluxes in response to aboveground JA treatment, heat stress and their interaction in a controlled climate chamber experiment. Continuous online VOC measurements by PTR-TOF-MS showed an inverse pattern of total needle and root VOC emissions, when plants were treated with JA and heat. While needle sesquiterpene emissions increased nine-fold one day after JA application, total root VOC emissions decreased. This was mainly due to reduced emissions of acetone and monoterpenes by roots. In response to aboveground JA treatment, root total carbon emitted as VOCs decreased from 31% to only 4%. While VOC emissions aboveground increased, net CO2 assimilation strongly declined due to JA treatment, resulting in net respiration during the day. Interestingly, root respiration was not affected by aboveground JA application. Under heat the effect of JA on VOC emissions of needles and roots was less pronounced. The buffering effect of heat on VOC emissions following JA treatment points towards an impaired defense reaction of the plants under multiple stress. Our results indicate efficient resource allocation within the plant to protect threatened tissues by a rather local VOC release. Roots may only be affected indirectly by reduced belowground carbon allocation, but are not involved directly in the JA-induced stress response.