Short-Term Responses of Photosystem II to Heat Stress in Cold-Acclimated Atrazine-Resistant and Susceptible Biotypes of Erigeron canadensis (L.)

1999 ◽  
Vol 54 (9-10) ◽  
pp. 665-670 ◽  
Author(s):  
Sándor Dulai ◽  
István Molnár ◽  
Evelin Péli ◽  
Endre Lehoczki
Keyword(s):  
Heat Treatment ◽  
Heat Stress ◽  
Elevated Temperature ◽  
Photosystem Ii ◽  
Significant Shift ◽  
Short Term ◽  
Erigeron Canadensis ◽  
Heat Treated ◽  
Temperature Dependences

When leaves of atrazine-resistant (AR) and atrazine-sensitive (S) Erigeron canadensis (L.) plants grown at 5 °C were exposed to an elevated temperature (35 °C) for 30 min, the critical (Tc) and peak temperatures (Tp) of the F0 vs. T curves were considerably higher for the leaves of the S biotype, but not for those of the AR biotype. The temperature dependences of Fv/Fm and ΔF/Fm′ were not greatly different for the heat-treated cold-acclimated AR biotype, in contrast with the situation for the S plants. This short-term heat treatment resulted in a more significant shift in the optimal thermal interval of CO2 fixation for the S than for the AR biotypes

Application of Tailored Heat Treated Blanks under Quasi Series Conditions

2007 ◽  
Vol 344 ◽  
pp. 383-390 ◽  
Author(s):  
Marion Merklein ◽  
Uwe Vogt
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Local Heat ◽  
Strength Distribution ◽  
Process Window ◽  
Short Term ◽  
Forming Process ◽  
Heat Treated ◽  
Set Up ◽  
The Impact

Tailored Heat Treated Blanks (THTB) are blanks that exhibit locally different strength specifically optimized for the succeeding forming process. The strength distribution is set by a local, short-term heat treatment modifying the mechanical properties of the material. Hence, THTB allow enhancing forming limits significantly leading to shorter and more robust manufacture process chains. In order to qualify the use of THTB under quasi series conditions, the interdependencies of the blank’s local heat treatment and the entire process chain of the car body manufacture have to be analyzed. In this respect, the impact of a short-term heat treatment on the mechanical properties of AA6181PX, a commonly used aluminum alloy in today’s car bodies, was studied. Also the influence of a short-term heat treatment on the coil lubricant, usually already applied by the material supplier, was given a closer look. Based on these experiments process restrictions for the application of THTB in an industrial automotive environment were derived and a process window for the THTB design was set up. In conclusion, strategies were defined how to enhance the found process boundaries leading to a more robust process window.

Experimental Investigation of Heat-Treated Aluminum Profiles

2015 ◽  
Vol 651-653 ◽  
pp. 59-64
Author(s):  
Marion Merklein ◽  
Matthias Graser ◽  
Michael Lechner
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Experimental Investigation ◽  
Material Flow ◽  
Material Characterization ◽  
Process Window ◽  
Short Term ◽  
Property Distribution ◽  
Heat Treated ◽  
Aluminum Profiles

Tailor Heat Treated Profiles (THTP) are profiles that exhibit local different mechanical properties optimized for a subsequent forming operation. The property distribution is realized by short term heat treatment before a forming operation. Based on the interaction of soft and hard areas the material flow can be improved and the formability can be enhanced. Prerequisite for a successful application of the technology is a comprehensive material characterization. Therefore, within this paper the influence of short term heat treatment on the mechanical properties of profiles will be presented. In particular, different heating technologies based on heat conduction and laser radiation are compared. Based on the results, a process window will be derived. All investigations were performed using the precipitation hardenable aluminum alloy EN AW 6060.

Precipitation Behaviour and Mechanical Properties during Short-Term Heat Treatment for Tailor Heat Treated Profiles (THTP) of Aluminium Alloy 6060 T4

2016 ◽  
Vol 877 ◽  
pp. 400-406 ◽  
Author(s):  
Hannes Fröck ◽  
Matthias Graser ◽  
Benjamin Milkereit ◽  
Michael Reich ◽  
Michael Lechner ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Aluminium Alloy ◽  
Heat Treatments ◽  
Maximum Temperature ◽  
Short Term ◽  
Scanning Calorimetry ◽  
Heat Treated ◽  
Precipitation Behaviour ◽  
Dissolution And Precipitation

Precipitation hardening aluminium alloys are widely used for automotive applications. To enhance the application of aluminium profiles, improved formability is needed. Tailor Heat Treated Profiles (THTP) with locally different material properties attempt to increase formability e.g. in bending processes. Tailoring of local properties is obtained by a local short-term heat treatment, dissolving the initial precipitate state (retrogression) and still allowing subsequent ageing. In the present study, the dissolution and precipitation behaviour of the aluminium alloy EN AW-6060 T4 was investigated during heating with differential scanning calorimetry (DSC). Heating curves from 20 to 600 °C with heating rates of 0.01 up to 5 K/s were recorded. Interrupted heat treatments with different maximum temperatures were performed in a deformation dilatometer. Immediately afterwards, tensile tests were carried out at room temperature. The course of the recorded mechanical properties as a function of the maximum temperature is discussed with regard to the dissolution and precipitation behaviour during heating. Finally, the aging behaviour of the investigated alloy was recorded after different typical short-term heat treatments and is discussed with reference to the DSC‐curves. The correlation of the microstructure and the mechanical properties enables the derivation of optimal parameters for the development of THTP through a local softening.

scholarly journals Physiological Response to Short-Term Heat Stress in the Leaves of Traditional and Modern Plum (Prunus domestica L.) Cultivars

Horticulturae ◽  
2022 ◽  
Vol 8 (1) ◽  
pp. 72
Author(s):  
Marija Viljevac Vuletić ◽  
Ines Mihaljević ◽  
Vesna Tomaš ◽  
Daniela Horvat ◽  
Zvonimir Zdunić ◽  
...  
Keyword(s):  
Heat Stress ◽  
Elevated Temperature ◽  
High Temperature Stress ◽  
Guaiacol Peroxidase ◽  
Inadequate Response ◽  
Short Term ◽  
Modern Cultivar ◽  
Performance Indexes ◽  
Chlorophyll A Fluorescence Transients ◽  
The Impact

The aim of this study was to evaluate physiological responses to short-term heat stress in the leaves of traditional (Bistrica) and modern (Toptaste) plum cultivars. In this study, detached plum leaves were incubated at 25 °C (control) and 40 °C (stress). After 1 h of exposure to heat (40 °C), chlorophyll a fluorescence transients were measured, and several biochemical parameters were analyzed. Elevated temperature caused heat stress in both plum cultivars, seen as a decrease in water content (WT), but in the leaves of the cultivar Bistrica, an accumulation of proline and phenols, as well as an accumulation of photosynthetic pigments, suggest the activation of a significant response to unfavorable conditions. Conversely, in the leaves of Toptaste, a significant accumulation of malondialdehyde (MDA) and an activation of guaiacol peroxidase (GPOD), all together with a decreased soluble proteins content, indicate an inadequate response to maintaining homeostasis in the leaf metabolism. The impact of an elevated temperature on photosynthesis was significant in both plum cultivars as reflected in the decrease in performance indexes (PIABS and PItotal) and the maximum quantum yield of PSII (Fv/Fm), with significantly pronounced changes found in Toptaste. Unlike the traditional plum cultivar, Bistrica, in the modern cultivar, Toptaste, short-term heat stress increased the minimal fluorescence (F0) and absorption (ABS/RC), as well as Chl b in total chlorophylls. Additionally, the inactivation of RCs (RC/ABS) suggests that excitation energy was not trapped efficiently in the electron chain transport, which resulted in stronger dissipation (DI0/RC) and the formation of ROSs. Considering all presented results, it can be presumed that the traditional cultivar Bistrica has better tolerance to heat stress than the modern cultivar Toptaste. The cultivar, Bistrica, can be used as a basis in further plum breeding programs, as a source of tolerance for high temperature stress.

Examination the effect of post-hatch heat-treatment and heat-stress in Transylvanian Naked Neck chicken

2020 ◽  
Author(s):  
Roland Tóth ◽  
Nikolett Tokodyné Szabadi ◽  
Bence Lázár ◽  
Kitti Buda ◽  
Barbara Végi ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Heat Stress ◽  
Heat Shock ◽  
Heat Shock Proteins ◽  
Egg Production ◽  
Sperm Quality ◽  
Heat Shock Factors ◽  
Expression Levels ◽  
Heat Treated ◽  
Shock Proteins

Abstract Background One of the most critical global problem nowadays is the increased environmental temperature. Agriculture is very susceptible to this adverse effect because the productivity of animals and poultry decreased. Although several studies reported the effects of heat-stress in chicken, the expression profile of heat-shock proteins and heat shock factors was not investigated in the gonads and germ cells of Transylvanian Naked Neck chickens. Methods In the first experiment, 24 hours after hatching 80 chicks were heat treated on 38.5oC ambient temperature with 60% humidity for 12 hours. After maturation, their primary productivity parameters, such as egg production, abnormalities in embryo development, sperm quantity, concentration, and motility were studied following two weeks of heat-stress on 30 °C room temperature. In the second experiment, the thermal manipulation of 60 chicks was the same but 15 treated and 15 control chicks were sacrificed immediately after the treatment. The other 15–15 chickens were raised to maturity. Expression levels for two heat-shock proteins and four heat shock factors were determined by real-time PCR in the gonads of heat-treated and heat-stressed chickens. Results We found that the heat-treated layers had significantly higher egg production than the control group in heat-stressed conditions. In cockerels, the sperm quality did not differ significantly between the heat-treated and heat-stressed group and the heat-stressed but not heat-treated group. We examined the expression pattern of HSPs and HSFs in the gonads. We found that the expression of HSP90 and HSF4 increased significantly (p < 0.05) in heat-treated female chick gonads but in adult females the expression of HSF2 and HSF3 were significantly lower compared to the control. In case of adult heat-treated males, the HSP70, HSF1 and HSF3 expression levels showed a significant increase in both gonads, compared to the control expression levels (P < 0.05). Conclusion Heat shock proteins and heat-shock factors protect cells against different stressors, including heat stress. Our findings show a significant effect on egg production but not on the sperm quality after post-hatch heat treatment in heat stress condition. The presented significant differences might be related to the increased expression level of HSP90 and HSF4 in heat-treated chickens.

Effects of growth temperatures of 5 and 25°C on long-term responses of photosystem II to heat stress in atrazine-resistant and susceptible biotypes of Erigeron canadensis

1998 ◽  
Vol 25 (2) ◽  
pp. 145 ◽  
Author(s):  
Sándor Dulai ◽  
István Molnár ◽  
Endre Lehoczki
Keyword(s):  
Heat Stress ◽  
Co2 Fixation ◽  
D1 Protein ◽  
Heat Sensitivity ◽  
Erigeron Canadensis ◽  
Temperature Dependences ◽  
Two Temperatures ◽  
Modulated Fluorescence ◽  
Induced Changes

When leaves of atrazine-resistant (AR) and atrazine-sensitive (S) plants of Erigeron canadensis (L.) Cronq. grown at 25°C were exposed to continuously rising temperatures, the heat-induced changes in the initial level (F0) of modulated fluorescence indicated an enhanced heat sensitivity of the chloroplasts in the leaves of the AR biotype. The critical (Tc) and peak temperatures (Tp) of the F0 v. T curves for the leaves of the S biotype grown at 5Q°C were considerably lower, in contrast with the leaves of the AR biotype, for which these values were very similar to those at 25°C. For the warm and cold-acclimated AR biotype, the temperature dependences of the fluorescence quenching parameters were not greatly different, in contrast with the S plants. The different growth temperatures resulted in a shift in the optimal thermal interval of CO2 fixation between the cold and warm-acclimated S biotype, whereas this interval was nearly the same for the AR biotype grown at the two temperatures. The results suggest that, besides the D1 protein mutation, the growth temperature independence of the thylakoid fluidity, over and above a higher susceptibility to heat stress, may cause the limited capacity of acclimation to temperature in AR plants.

Elevated Temperature Treatment Induced Alteration in Thylakoid Membrane Organization and Energy Distribution between the Two Photosystems in Pisum sativum

2002 ◽  
Vol 57 (9-10) ◽  
pp. 836-842 ◽  
Author(s):  
Prasanna Mohanty ◽  
Bagawatula Vani ◽  
Jogadhenu S. S. Prakash
Keyword(s):  
Heat Treatment ◽  
Elevated Temperature ◽  
Pisum Sativum ◽  
Fold Increase ◽  
Blue Shift ◽  
Temperature Treatment ◽  
Cd Spectra ◽  
Pea Seedlings ◽  
Heat Treated

Two-week-old pea (Pisum sativum var. Arkal) plants were subjected to elevated temperature (38 °C/42 °C) in dark for 14−15 h. The effect of heat treatment on light- induced phosphorylation of LHCII and LHCII migration in the thylakoid membranes were investigated. The heat treatment did cause a substantial (more than two fold) increase in the extent of LHCII phosphorylation as compared to the control. Upon separation of appressed and nonappressed thylakoid fractions by digitonin treatment, the heat-treated samples showed a decrease in LHCII-related polypeptides from the grana stack (appressed region) over the control. Further, a small increase in the intensity of these (LHCII-related) bands was detected in stromal thylakoid fraction (non-appressed membranes). This suggests an enhanced extent of migration of phosphorylated LHCII from appressed to non-appressed regions due to in vivo heat treatment of pea plants. We also isolated the LHCII from control and heat treated (42 °C) pea seedlings. Analysis of CD spectra revealed a 5D6 nm blue shift in the 638 nm negative peak in heat treated samples suggesting alteration in the organization of Chl b in the LHCII macro-aggregates. These results suggest that in vivo heat stress not only alters the extent of migration of LHCII to stromal region, but also affects the light harvesting mechanism by LHCII associated with the grana region.

The C14-to-C15 Transformation in Cr2Hf

1994 ◽  
Vol 364 ◽  
Author(s):  
K. S. Kumar ◽  
P. M. Hazzledine
Keyword(s):  
Heat Treatment ◽  
Phase Diagram ◽  
Solid Solution ◽  
Elevated Temperature ◽  
Room Temperature ◽  
Single Phase ◽  
Higher Order ◽  
Two Phase ◽  
Heat Treated ◽  
Order Structures

AbstractThree alloys, single-phase Cr2Hf, a two-phase alloy consisting of Cr solid solution and Cr2Hf, and a two-phase alloy consisting of Hf solid solution and Cr2Hf were cast and heat treated. The C14-to- C15 transformation of the Laves phase, Cr2Hf was studied as a function of heat treatment. According to the existing phase diagram, the Cr2Hf phase exhibits a C14 structure at elevated temperature but transforms to the C15 structure at lower temperatures. Such transformations are known to be extremely sluggish. In the present study, the Cr2Hf phase was found to retain the C14 structure at room temperature in all three compositions in the cast or cast and forged conditions; upon subsequent heat-treatment at various temperatures and time-at-temperatures, however, the C14 structure decomposes to a variety of higher order structures including the 16H, 10H, and 4H structures. These superstructures can be viewed as containing various percentages of the cubic and hexagonal stacking. The C15 structure was not observed for any of the conditions considered.

Heat stress during mid-pregnancy in sheep and the consequences for placental and fetal growth

1993 ◽  
Vol 120 (2) ◽  
pp. 265-271 ◽  
Author(s):  
G. J. McCrabb ◽  
B. J. McDonald ◽  
L. M. Hennoste
Keyword(s):  
Heat Treatment ◽  
Heat Stress ◽  
Fetal Growth ◽  
Rectal Temperature ◽  
Late Pregnancy ◽  
Fetal Weight ◽  
Research Station ◽  
Hot Climate ◽  
Heat Treated ◽  
The Relationship

SUMMARYAn experiment was conducted at Toorak Research Station, Julia Creek, in semi-arid northern Australia (141° E, 21° S) during 1990 to determine the relationship between placental and fetal weight in sheep after placental growth had been restricted by chronic heat stress during mid-pregnancy. Placental and fetal weight were measured in single bearing ewes housed either in a thermoneutral environment throughout pregnancy, or in a heated room between the 30th and 80th days of pregnancy followed by a thermoneutral environment until the 140th day of pregnancy. The placental weight of the heat-treated ewes was lower than that of the control ewes at the 80th (P< 0·05) and 140th (P< 0·01) days of pregnancy. Fetal weight and dimensions did not differ significantly between control and heat-treated ewes at the 80th day of pregnancy, although fetal weight (P< 0·01) and fetal dimensions (P< 0·05) for the previously heat-treated ewes were lower than those for the control ewes at the 140th day of pregnancy. Placental and fetal weight at the 140th day of pregnancy were correlated (P< 0·05) with the rectal temperature of ewes measured at 08.00 and 16.30 h during the period of heat-treatment, but not with the change in rectal temperature between 08.00 and 16.30 h. It was concluded that restricted placental growth in heat-treated ewes retarded fetal growth during late pregnancy even in the absence of heat treatment, and it is suggested that selection of ewes which can maintain normal rectal temperatures during periods of heat stress would produce lambs of normal birthweight in a hot climate.

scholarly journals Effect of Post-Hatch Heat-Treatment in Heat-Stressed Transylvanian Naked Neck Chicken

Animals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1575
Author(s):  
Roland Tóth ◽  
Nikolett Tokodyné Szabadi ◽  
Bence Lázár ◽  
Kitti Buda ◽  
Barbara Végi ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Heat Stress ◽  
Heat Shock ◽  
Egg Production ◽  
Sperm Quality ◽  
Expression Level ◽  
Heat Shock Factors ◽  
Naked Neck ◽  
Heat Treated ◽  
Shock Proteins

Although numerous studies reported the effects of heat stress in chickens, it was not investigated in the Transylvanian Naked Neck breed. In our research, Transylvanian Naked Neck chickens, 24 hours after hatching, were heat-treated at 38.5 °C for 12 hours. We compared the control and heat-treated adult chickens’ productivity parameters following 12 weeks of heat-stress at 30°C. We found that the heat-treated layers had significantly higher egg production in heat stress, but in cockerels, the sperm quality did not differ significantly between the two groups. To detect the effect of heat-treatment on a molecular level, the expression of two heat-shock proteins and four heat-shock factors were analysed in the gonads of control and heat-treated chickens. We found that the expression level of HSP90 and HSF4 increased significantly in heat-treated female chicken gonads. Still, in adult females, the expression of HSF2 and HSF3 were substantially lower compared to the control. In adult heat-treated males, the HSP70, HSF1 and HSF3 expression levels showed a significant increase in both gonads compared to the control. We think that the presented significant differences in egg production might be related to the increased expression level of HSP90 and HSF4 in heat-treated female gonads.

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