Detrimental Effect Of High Temperature Research Articles

Exploring the Impact of Diverse Cooling Duct Configurations on Photovoltaic Panel Performance

Photovoltaic (PV) panels are an emerging technology that captures solar energy and produces electricity. One key concern with PV panels is the detrimental effect of high temperatures on their performance and efficiency, which is leading to a shorter service life. Cooling the panels can help to maintain appropriate working temperatures, reduce the adverse effects of heat, and increase overall energy production. This research aims to investigate experimentally and numerically the effectiveness of a cooling channel with different configurations in lowering PV panels' temperature. The findings of the experiments show that cooling methods improved panel efficiency by 0.35% and reduced the intake temperature by 7%. In numerical analysis, different 3D cooling channel geometries were investigated, and the tapered duct was found to be the best in reducing Tav at 1.73%.

Ambient temperatures associated with reduced cognitive function in older adults in China

The cognitive function status of older adults determines the social function and living quality of older adults, which is related to the healthy development and stability of the society. However, the impact of high or low ambient temperature on cognitive function in older adults remains unclear. Based on data from the Chinese Longitudinal Healthy Longevity Survey (CLHLS), we comprehensively assessed the impact of ambient temperature on the cognitive function of older adults in this study. The findings exhibited that for each 1 °C ascent in monthly temperature of high temperature, the examination score of global cognitive function of older adults decreased by 0.48 (95% CI 0.21–0.74), which was greater than that of 0.14 (95% CI 0.06–0.25) for each 1 °C reduction in low temperature. Overall, the detrimental effect of high temperature on cognitive function in older adults was more significant than that of low temperature, including on the five sub-cognitive functions involved. Our research provides vital technical guidance and reference for the health protection and prevention of cognitive function of older adults in specific external environmental conditions under the current climatic variation and temperature rise.

Microstructure and ionic conductivities of NASICON-type Li1.3Al0.3Ti1.7(PO4)3 solid electrolytes produced by cold sintering assisted process

Li1.3Al0.3Ti1.7(PO4)3 (LATP) is a promising solid electrolyte for lithium-ion batteries. However, it is challenging to densify LATP ceramics at reduced sintering temperature while preserving their electrical properties. Herein, LATP ceramics were pre-densified via cold sintering process (CSP) at 250 °C for 1 h and exhibited room temperature ionic conductivity of 2.01 × 10−6 S/cm. Subsequent post-annealing at as low as 900 °C for 1 h resulted in two orders of magnitude improvement in both grain boundary conductivity and total conductivity, compared to those of as-CSPed LATP. The optimal total conductivity (4.29 × 10−4 S/cm) obtained from post-annealed material is among the best reported values so far. It is also 5 times greater than the conductivity (8.51 × 10−5 S/cm) of the conventionally sintered LATP. We propose that post-annealing effectively eliminates amorphous insulating phases generated during CSP and promotes crack-free microstructure with moderate grain growth, which collectively contributes to dramatically enhanced conductivity. This work unambiguously demonstrates that CSP-assisted process can avoid the detrimental effects of high temperature associated with conventional sintering on microstructure and conductivity, and thus is a cost-effective processing route for fabrication of solid-state electrolytes for battery applications.

Performance of Winter-Sown Chickpea Breeding Lines with Contrasting Levels of Resistance to Ascochyta Blight

Multi-environment field testing of chickpea accessions winter sown in Southern Spain showed that environmental effects on yield were more important than genotypic effects and GEI. The most detrimental factor on grain yield was ascochyta blight infection. We did not find a significant effect of low temperatures on yield in the environments studied, probably due to the mild winters in the area. On the contrary, we found detrimental effects of high temperatures at the reproductive stage, particularly with numbers of days with Tmax >30 °C. We found that genotypic effects were larger than the environmental on ascochyta infection as we included accessions previously selected for their levels of resistance or susceptibility. Biplots based on the WAASB/productivity ratio highlighted AS19, AS30, AS23, AS26, and AS18 accessions as the best for productivity and stability of yield, matching with those with a lower ascochyta blight infection. The MTSI index also identified these as the best accessions for the region.

High Temperature and Elevated CO2 Modify Phenology and Growth in Pepper Plants

The aim of this study was to determine the effect of temperature and CO2 on seed emergence, seedling quality, and phenological stage of Capsicum chinense and Capsicum annum cultivated in four controlled growth chambers (C1: 30 °C and 400 μmol CO2 mol−1; C2: 40 °C and 1200 μmol CO2 mol−1; C3: 30 °C and 1200 μmol CO2 mol−1; C4: 40 °C and 400 μmol CO2 mol−1). Neither temperature nor elevated CO2 influenced seed emergence, although differences were observed in seedling mortality, with high temperature affecting seedling survival in both species; the mortality rate at 40 °C was 20 and 53% in C. annuum and 45 and 58% in C. chinense at 400 and 1200 μmol CO2 mol−1, respectively. Differences were also observed in growth parameters, where positive effects were observed on leaf area, which reached 45.9 cm2 in C. annuum and 23.9 cm2 in C. chinense with elevated CO2 at 30 °C, but negative effects were observed with high temperature. CO2 enrichment increased flower and fruit production per plant. However, high temperature delayed flower phenology, increased flower abortion and inhibited fruit set. Elevated CO2 counteracted the detrimental effects of high temperature on growth parameters and flower number, but this was not sufficient to prevent flower abortion and the detrimental morphological characteristics of fruit caused by a temperature of 40 °C.

Defining region-specific heatwave in China based on a novel concept of “avoidable mortality for each temperature unit decrease”

The distribution of temperature and temperature-health association varied largely across different regions in China, a region-specific definition for heatwave was therefore needed. We collected the data on daily mortality, meteorological factors and air pollution in 84 Chinese cities during 2013–2016, which was divided into seven regions. Based on the association between daily maximum temperature and mortality in each city in a threshold distributed lag non-linear model, where the threshold was defined as the temperature corresponding to the lowest mortality risk, we calculated the number of deaths that could be avoided for 1 °C decrease in maximum temperature under different thresholds, then a random-effect meta-analysis was used to generate regional results, in which the temperature with the highest avoidable mortality number for 1 °C decrease was considered as the most appropriate heatwave definition. We observed an immediate detrimental effect of high temperature within three lag days. Our analysis suggested to use 29.5 °C, 31.5 °C, 29.0 °C, 31.5 °C, 30.0 °C, and 28.5 °C as the heatwave standard for east, north, northeast, central, south, and southwest region, with the avoidable mortality number of 1.54 (95 % Confidence interval (CI): 0.88, 2.19), 0.55 (95 % CI: 0.16, 0.94), 0.59 (95 % CI: 0.32, 0.86), 1.14 (95 % CI: 0.68, 1.59), 1.22 (95 % CI: 0.54, 1.90), and 0.78 (95 % CI: 0.01, 1.55), respectively, while the estimated number 0.19 (95 % CI: −0.02, 0.40) in northwest region was not statistically significant. The concept of ‘avoidable mortality for 1 °C decrease’ was proposed to define the heatwave event, and varied maximum temperature between 28.5 and 31.5 °C was suggested for region-specific heatwave definition in China.

Fracture of fibre-reinforced cementitious composites after exposure to elevated temperatures

The effects of aramid, glass, basalt and polypropylene (PP) fibres in a fibre-reinforced cementitious composite (FRCC) were examined. Specifically, this work investigated the effects of the fibres on the compressive strength, splitting tensile strength, flexural strength and fracture behaviour of the FRCC after exposure to normal and elevated temperatures. Relationships for the compressive, splitting tensile and flexural strengths of the FRCC were developed based on response surface methodology. The microstructures of samples at various temperatures were explored using scanning electron microscopy. The experimental results showed that the fracture energies of the mixtures were related to both temperature and fibre type. The most detrimental effects of high temperatures were on the fracture energy, which diminished by about 35% and 69% on average at 100°C and 300°C, respectively. The samples reinforced with PP fibres exhibited the maximum fracture energy at 20°C. In other words, the energy absorption of the PP fibres was far more than that of the other fibre types investigated. Finally, it was found that use of fibres with higher melting points did not improve the fracture energy of the specimens after exposure to elevated temperatures.

Thermal damage and fatigue estimation in heavily loaded lubricated rolling/sliding contacts with Micro-Geometry

A previously developed model for heavily loaded Elastohydrodynamically lubricated (EHL) contacts with surface micro-geometry for the calculation of surface distress (micropitting), based on high-cycle fatigue and mild wear competition, is herewith further extended. It now includes the effects of frictional heating with a sharp temperature rise developed in the rolling contact. For this, a new surface damage model, originated in creep modelling, is included. With this modification, the detrimental effect of high temperature developed in the rolling/sliding contact can now be accounted for. This model can consider sharp or moderate surface temperature rise during over-rolling is found in bearings and gears operating at high speeds or under the combination of speeds, loads and unfavourable environmental aspects. The present model introduces a threshold limit made of the combination of temperature and (heating time under stress) load cycles above which the conditions in the rolling contact are deemed damaging for the steel microstructure and the tribological functionality of the rolling contact. The surface damage model is first compared with laboratory experiments in rolling/sliding conditions and then applied to study combinations of loads, sliding speeds and the effect in rolling bearings. The ability of the present model to include damaging mechanisms, other than classical metal fatigue, increases the flexibility in contact surface damage modelling and allows for the accounting of phenomena up to now excluded from better estimation of the machine elements surface life.

Packaging in a High O2 or Air Atmospheres and in Microperforated Films Effects on Quality of Button Mushrooms Stored at Room Temperature

Cold conditions are obligatory for mushrooms storage. However, in most cases, the cold chain is interrupted at various stages. Thus, is of great importance to propose a packaging system capable of inhibiting the detrimental effect of high temperature on mushrooms’ quality. The study evaluates the effect of high oxygen atmosphere (80% O2) in conjunction with films of different levels of microperforations (polysulfon (PSF) films, low: PSF_1000, PSF_2000; medium: PSF_3500; and high: PSF_7000) on antioxidant capacity, volatile compounds profile, sensory acceptance, and quality of mushrooms stored at 20 °C. Results showed that high O2 atmosphere inhibits the respiration rate of mushrooms. Application of high O2 atmosphere and film of high level of microperforations preserved desired color and profile of volatile compounds, ensured consumers color and overall acceptance. In turn, the single effect of the perforation level of the applied film was observed for antioxidant capacity, weight loss, vitamin C, malonylodialdehyde (MDA), and phenolics content. Packaging in low microperforated films led to the least amount of phenolics, highest MDA content, and poor antioxidant capacity in mushrooms. In turn, packaging with films of a medium level of perforation contributed to the highest vitamin C and phenolic content. There was no effect of treatment on texture, maturity index, protein content, and percentage of open capped mushrooms.

A model for rolling bearing life with surface and subsurface survival: Surface thermal effects

A previously developed model for bearing life calculation, based on high-cycle fatigue, including the separation of the surface and the subsurface survival of the rolling contact, is herewith further extended. It now includes the effects of frictional heating with a sharp temperature rise developed in the rolling contact. For this, a new surface damage integral, based on the creep mechanism, is included in the model. With this modification, the detrimental effect of high temperature developed in the rolling contact can now be accounted for. Sharp surface temperature rise during over-rolling are found in bearings operating at high speeds or under the combination of speeds, loads and unfavourable environmental temperatures. The present model introduces a threshold limit value of temperature above which the temperature in the rolling contact is deemed damaging for the steel microstructure and the tribological functionality of the rolling contact. The surface creep-damage model is first calibrated with endurance tests of bearings and then applied to study combinations of loads and speeds and the effect of the steel thermal conductivity on the life expectancy of the bearing. The ability of the present model to include damaging mechanisms, other than classical metal fatigue, increases the flexibility in bearing life predictions and allows to account for phenomena hitherto excluded from the estimation of the bearing fatigue life.

High-temperature effect on the mechanical performance of screwed CFRPI–TC4 alloy joints repaired with metal inserts

This paper seeks to study high-temperature effect on mechanical performance of screwed single-lap carbon fiber-reinforced polyimide–TC4 titanium alloy joints repaired with metal inserts. Quasi-static tension tests were conducted at room temperature (RT) and 250℃ to determine the joint strength and stiffness of repaired joints with metal inserts. Based on the experimental results, high-temperature effect on joint strength and stiffness and insert repair efficiency were analyzed and discussed. A new analytical model was established to evaluate the effect of high temperature on joint stiffness. It is concluded that (1) joint strength and stiffness for all configurations are lower at 250℃ than that at RT, showing the expected detrimental effect of high temperature on joint strength and stiffness. The reductions in joint strength and stiffness depend on the joint configuration; (2) the repair efficiencies of embedded conical nut for joint strengths of protruding and countersunk head screw joints decrease, but those for joint stiffness increase at 250℃ as against at RT. Unlike the repair efficiencies of embedded conical nut, the repair efficiency of bushing for joint strength is slightly greater, but that for joint stiffness is less at 250℃ than at RT; and (3) the developed analytical model is capable of predicting the displacement of screwed single-lap carbon fiber-reinforced polyimide–TC4 joints at RT and high temperature, and there is good agreement between the experimental data and the predicted curves.

Deeper insight into lifetime-engineering in 4H-SiC by ion implantation

Lifetime-engineering in 4H-SiC is important to obtain a low forward voltage drop in bipolar devices with high blocking voltages above 10 kV. It is known that the implantation of carbon and subsequent thermal annealing can be used to improve the minority carrier lifetime of as-grown epitaxial layers due to annihilation of carbon vacancies and, therefore, reduce the lifetime limiting defect Z1/2. In this paper, the ion implantation of other ions (N, Al, B, and As) besides carbon and their impact on minority carrier lifetime and point defect concentration are shown. Special attention is paid to the effect of ion implantation with subsequent electrical activation by high temperature annealing. A strong influence of the implantation dose and, therefore, corresponding resulting doping concentration was found. A lifetime enhancement could be found for some implanted species for higher implantation doses whereas the detrimental effect of high temperature annealing dominated at low implantation doses. The results reveal that the implantation dose and the occupied lattice sites are important parameters to achieve a lifetime enhancement. A model is presented which explains the different impacts of various implanted ions and a more detailed understanding of lifetime-engineering by ion implantation. With this knowledge, it was possible to reduce the detrimental Z1/2 defect in a large part of thick epitaxial layers with conventional shallow ion implantation and high temperature annealing. Consequently, the minority carrier lifetimes of the epitaxial layers could be enhanced.

Impacts of calcination on surface-clean supported nanoparticle catalysts

Traditional methods of preparing size-controlled supported nanoparticle catalysts typically require the use of stabilizing ligands that passivate the nanoparticle surface to prevent overgrowth and aggregation. The presence of these ligands on catalytic surfaces can be detrimental to activity and are typically removed via a high-temperature annealing step, which ultimately results in changes to nanoparticle morphology and thus, reduced activity. We previously demonstrated that silylamine switchable surfactants can be used to synthesize and deposit highly active nanoparticles on to a support surface while preserving monodispersity. Here, we demonstrate using XPS that supported nanoparticles prepared in this manner are surface-clean after deposition, eliminating the need for traditional activation steps. Further, it is shown that even low-temperature calcinations have detrimental effects on the catalyst properties including changes in nanoparticle morphology that result in a significant decrease in activity, a change in surface hydrophilicity, a change in activation energy, and results in the formation of an induction time when utilized in the hydrogenation of 4-nitrophenol. While calcination remains a widely used method of catalyst activation, the detrimental effects of high temperatures on catalyst properties are often overlooked.

Comparative study of basal thermo tolerant attributes in tolerant and susceptible wheat cultivars

Two wheat cultivars, viz. C306 and HT41, have been evaluated for their responses to heat stress in terms of some biochemical and physiological attributes. During the exposure to high temperature (40°C for 6 and 12 h), a significant reduction in RWC and FW was recorded in HT41 which was also associated with heat susceptibility. The detrimental effects of high temperature were also apparent in terms of lipid peroxidation, chlorophyll content, H2O2 generation and electrolyte leakage and these were more pronounced in HT 41. Accumulation of osmolytes like proline, total sugar increased due to heat injury and also varied between the two cultivars. In this present study evaluation and analysis of these biochemical and physiological characters under heat stress could unravel the mechanism of basal thermotolerance and thus might be useful as genetic stock to develop wheat tolerant varieties.

Germline Development of Genetically Female Nile Tilapia (Oreochromis niloticus) Reared under Different Temperature Regimes

In teleosts, elevated temperature during embryogenesis can act on germline cell development, which in turn plays a role for sexual fate. In Nile tilapia, a species with high-temperature-induced masculinization, little is known about the effects of increased temperature on gonadal development in non-masculinized females. The aim of the present work was to investigate persistent effects on the germline of genetically female (XX) Nile tilapia reared at normal (28°C) or elevated temperature (36°C) during the critical time of gonadal sex differentiation at 10 to 20 days post fertilization. Non-sex-reversed females were compared to control females to determine persistent effects of temperature on subsequent ovarian development using histological approaches. Germline stem cells were identified using the germline marker Vasa in combination with the proliferation marker PCNA. Vasa- and PCNA-positive germline stem cells were found in ovaries of both high-temperature-treated and control females. In both groups, ovarian germline stem cells were located at the germinal epithelium of the ovigerous lamellae. Although no detrimental effects of high temperature on gonadal development in female Nile tilapia were observed, implications on the reproductive fitness caused by elevated temperature need to be investigated in greater depth.

Independent and combined effects of high temperature and drought stress around anthesis on wheat

AbstractHigh temperature and drought stress are projected to reduce crop yields and threaten food security. While effects of heat and drought on crop growth and yield have been studied separately, little is known about the combined effect of these stressors. We studied detrimental effects of high temperature, drought stress and combined heat and drought stress around anthesis on yield and its components for three wheat cultivars originating from Germany and Iran. We found that effects of combined heat and drought on the studied physiological and yield traits were considerably stronger than those of the individual stress factors alone, but the magnitude of the effects varied for specific growth‐ and yield‐related traits. Single grain weight was reduced under drought stress by 13%–27% and under combined heat and drought stress by 43%–83% but not by heat stress alone. Heat stress significantly decreased grain number by 14%–28%, grain yield by 16%–25% and straw yield by 15%–25%. Cultivar responses were similar for heat but different for drought and combined heat and drought treatments. We conclude that heat stress as imposed in this study is less detrimental than the effects of those other studied stresses on growth and yield traits.

Reproductive performance of the hemlock looper,Lambdina fiscellaria, as a function of temperature and population origin

In a recent study of the hemlock looper (HL), Lambdina fiscellaria (Guenee) (Lepidoptera: Geometridae), long exposure of early-diapausing eggs to high temperatures considerably reduced their ability to hatch. This finding raised the possibility that adults could also be negatively affected by increasing temperatures if they reproduced too early in the season in response to global warming. To investigate this hypothesis, newly formed HL pupae from three populations of eastern Canada - Quebec (QC), Newfoundland (NL), and Labrador (LB) - were submitted to four constant temperatures (10, 15, 20, or 25 °C) during pupal and adult development. The effect of population origin on HL reproduction was generally negligible. Mating probability was high at 15 and 20 °C (0.86 and 0.83, respectively), quite low at 10 °C (0.53), and even lower at 25 °C (0.38). Mating started earlier in the night and lasted longer as temperature decreased. Both productivity and absolute fecundity increased when temperature increased from 10 to 15 °C and then decreased slowly as temperature increased further. Over populations and temperatures, relative fecundity averaged 0.95, indicating that females had enough time to lay most of their eggs before they died. High temperatures had a deleterious effect on egg fertility: between 10 and 20 °C, relative fertility was about 0.90, but it dropped to 0.51 at 25 °C. The average proportion of fertile eggs declined from 0.88 in the first quarter of the egg-laying period to 0.57 in the last quarter, suggesting lower sperm count or viability, or deterioration of the oocytes as the egg-laying period progresses. Based on these findings, we argue that the production of an additional fifth instar among HL populations of southern origin can be viewed as an adaptive mechanism allowing adults to postpone reproduction or the egg-laying period in order to mitigate the detrimental effect of high temperatures on their probability of mating successfully or that of laying fertile eggs.

Thermal limits for the establishment and growth of populations of the invasive apple snail Pomacea canaliculata

Pomacea canaliculata is a South American freshwater snail considered as one of the world’s worst invasive alien species. A temperature of around 25 °C has usually been considered to be optimal for rearing P. canaliculata. Nevertheless, snails have not been reared under a wide range of temperatures to reveal the optimum for performance in terms of population increase. We investigated the effect of temperature on growth, survival and reproduction, estimating demographic parameters for P. canaliculata in the wide range of temperatures at which these snails are active (15–35 °C). No reproductive activity was evidenced for the snails reared at 15 °C, probably explained by the small sizes attained at this temperature. Temperatures above 25 °C did not promote a significant acceleration in growth so higher temperatures will not result in a reduction in time to reach maturity. In fact, snails from 25 and 30 °C began reproduction at the same age. We report here for the first time a detrimental effect of high temperatures that provoked a significant decrease in the contribution of snails to the next generation: the viability of eggs from the snails reared at 30 °C was very low and the snails exposed to a constant water temperature of 35 °C were unable to produce eggs. Our findings reveal a new environmental constraint that could be a determinant of the range limits of this species in invaded regions, especially during the coming decades, anticipating the scenario predicted from global warming.

Viscoelastic properties of orthodontic adhesives used for lingual fixed retainer bonding

ObjectiveTo evaluate the viscoelastic properties of two experimental BPA-free and one BisGMA-based orthodontic resin composite adhesives for bonding fixed retainers. MethodsA commercially available BisGMA-based (TXA: Transbond LR) and two bisphenol A-free experimental adhesives (EXA and EXB) were included in the study. The viscoelastic behavior of the adhesives was evaluated under static and dynamic conditions at dry and wet states and at various temperatures (21, 37, 50°C). The parameters determined were shear modulus (G), Young’s modulus (E) under static testing and storage modulus (G1), loss tangent (tanδ) and dynamic viscosity (n*) under dynamic testing. Statistical analysis was performed by 2-way ANOVA and Bonferroni post-hoc tests (α=0.05). ResultsFor static testing, a significant difference was found within material and storage condition variables and a significant interaction between the two independent variables (p<0.001 for G and E). EXA demonstrated the highest G and E values at 21°C/dry group. Dry specimens showed the highest G and E values, but with no significant difference from 21°C/wet specimens, except EXA in G. Wet storage at higher temperatures (37°C and 50°C) adversely affected all the materials to a degree ranging from 40 to 60% (p<0.001). For dynamic testing, a significant difference was also found in material and testing condition groups, with a significant interaction between the two independent variables (p<0.001 for G1 and n*, p<0.01 for tanδ). Reduction in G1, and n* values, and increase in tanδ values were encountered at increased water temperatures. SignificanceThe apparent detrimental effect of high temperature on the reduction of properties of adhesives may contribute to the loss of stiffness of the fixed retainer configuration under ordinary clinical conditions with unfavorable effects on tooth position and stability of the orthodontic treatment result.

A combined application of biochar and phosphorus alleviates heat-induced adversities on physiological, agronomical and quality attributes of rice

Present study examined the influence of high-temperature stress and different biochar and phosphorus (P) fertilization treatments on the growth, grain yield and quality of two rice cultivars (IR-64 and Huanghuazhan). Plants were subjected to high day temperature-HDT (35 °C ± 2), high night temperature-HNT (32 °C ± 2), and control temperature-CT (28 °C ± 2) in controlled growth chambers. The different fertilization treatments were control, biochar alone, phosphorous (P) alone and biochar + P. High-temperature stress severely reduced the photosynthesis, stomatal conductance, water use efficiency, and increased the leaf water potential of both rice cultivars. Grain yield and its related attributes except for number of panicles, were reduced under high temperature. The HDT posed more negative effects on rice physiological attributes, while HNT was more destructive for grain yield. High temperature stress also hampered the grain appearance and milling quality traits in both rice cultivars. The Huanghuazhan performed better than IR-64 under high-temperature stress with better growth and higher grain yield. Different soil fertilization treatments were helpful in ameliorating the detrimental effects of high temperature. Addition of biochar alone improved some growth and yield parameters but such positive effects were lower when compared with the combined application of biochar and P. The biochar+P application recorded 7% higher grain yield (plant−1) of rice compared with control averaged across different temperature treatments and cultivars. The highest grain production and better grain quality in biochar+P treatments might be due to enhanced photosynthesis, water use efficiency, and grain size, which compensated the adversities of high temperature stress.