Effect of Constant Temperature Treatments Followed by Fluctuating Temperatures on the Softening of Hard Seeds of Trifolium subterraneum L

1981 ◽  
Vol 8 (6) ◽  
pp. 547 ◽  
Author(s):  
GB Taylor
Keyword(s):  
Constant Temperature ◽  
Early Period ◽  
Trifolium Subterraneum ◽  
Degradation Process ◽  
Temperature Treatment ◽  
Temperature Dependent ◽  
Thermal Degradation Process ◽  
Softening Process ◽  
Distinct Temperature ◽  
Fluctuating Temperatures

Three experiments are described in which the effects of constant temperatures ranging from 15 to 80°C, followed by diurnally fluctuating temperatures of 60/15°C were compared on seed softening in three cultivars of T. subterraneum. Constant temperature treatments alone produced relatively few soft seeds, but rapid seed softening ensued within a few days of subsequent fluctuating temperature treatment. The higher and the longer the constant temperature pretreatment, the more soft seeds were obtained. The rate at which this preconditioning of the seed took place was highest in the early stages of exposure to constant temperatures. Differences between cultivars and between temperature treatments were established mainly during this early period of constant temperature treatment. Rates of change of temperature in the 60/15°C fluctuation treatment were important in the final seed softening process: the slower the rate of temperature change the more soft seeds were produced. It is suggested that two distinct temperature dependent processes are involved in seed softening. The first appears to be a thermal degradation process which probably results in weakening of the strophiolar region. Fluctuating temperatures bring about the second stage of softening in which the strophiole is rendered permeable to water.

Structural comparisons of pyrodextrins during thermal degradation process: The role of hydrochloric acid

2021 ◽  
Vol 349 ◽  
pp. 129174
Author(s):  
Huijia Mao ◽  
Zhijun Chen ◽  
Jie Li ◽  
Xueyang Zhai ◽  
Hongyan Li ◽  
...  
Keyword(s):  
Hydrochloric Acid ◽  
Thermal Degradation ◽  
Degradation Process ◽  
Thermal Degradation Process

Non-isothermal degradation kinetics for polycarbonate/ polymethylphenylsilsesquioxane composites

e-Polymers ◽  
2010 ◽  
Vol 10 (1) ◽  
Author(s):  
Jiangbo Wang ◽  
Zhong Xin
Keyword(s):  
Activation Energy ◽  
Thermogravimetric Analysis ◽  
Thermal Degradation ◽  
Flame Retardancy ◽  
Degradation Kinetics ◽  
Degradation Process ◽  
Nitrogen Atmosphere ◽  
Ozawa Method ◽  
Degradation Behaviors ◽  
Thermal Degradation Process

AbstractThe thermal degradation behaviors of PC/PMPSQ (polymethylphenylsilsesquioxane) systems were investigated by thermogravimetric analysis (TGA) under non-isothermal conditions in nitrogen atmosphere. During non-isothermal degradation, Kissinger and Flynn-Wall-Ozawa methods were used to analyze the thermal degradation process. The results showed that a remarkable decrease in activation energy ( E ) was observed in the early and middle stages of thermal degradation in the presence of PMPSQ, which indicated that the addition of PMPSQ promoted the thermal degradation of PC. Flynn-Wall-Ozawa method further revealed that PMPSQ significantly increased the activation energy of PC thermal degradation in the final stage, which illustrated that the PMPSQ stabilized the char residues and improved the flame retardancy of PC in the final period of thermal degradation process

scholarly journals A thermal degradation study of Y and La methanesulfonates

2006 ◽  
Vol 71 (8-9) ◽  
pp. 905-915
Author(s):  
Moura de ◽  
Jivaldo Matos ◽  
Farias de
Keyword(s):  
Thermal Analysis ◽  
Differential Scanning Calorimetry ◽  
Differential Thermal Analysis ◽  
Thermal Degradation ◽  
Degradation Process ◽  
Oxide Formation ◽  
Scanning Calorimetry ◽  
Degradation Study ◽  
Thermogravimetric Data ◽  
Thermal Degradation Process

The synthesis, characterization and thermal degradation of yttrium and lanthanum methanesulfonates is reported. The prepared salts were characterized by elemental analysis and infrared spectroscopy. The thermal degradation study was performed using thermogravimetry (TG), differential thermal analysis (DTA) and differential scanning calorimetry (DSC).Using the thermogravimetric data, a kinetic study of the dehydration ofY and Lamethanesulfonates was performed employing the Coats-Redfern and Zsak?methods. It was verified that under heating, yttrium and lanthanum methanesulfonates undergo three main processes: dehydration, thermal degradation and oxide formation. Furthermore, depending on the nature of the atmosphere, i.e., inert or oxidant, the thermal degradation process could be endothermic (N2) or exothermic (air).

scholarly journals Simultaneous Determination and Stability Studies on Diminazene Diaceturate and Phenazone Using Developed Derivative Spectrophotometric Method

2017 ◽  
Vol 2017 ◽  
pp. 1-6 ◽  
Author(s):  
Ruaa Mohamed Akode ◽  
Shaza Wagiealla Shantier ◽  
Elrasheed Ahmed Gadkariem ◽  
Magdi Awadalla Mohamed
Keyword(s):  
Simultaneous Determination ◽  
Correlation Coefficients ◽  
Degradation Process ◽  
Stability Studies ◽  
Temperature Dependent ◽  
First Order Kinetics ◽  
First Derivative Spectrophotometry ◽  
Aqueous Mixture ◽  
Photo Stability

This work presents UV first derivative spectrophotometry as a precise, accurate, and feasible method for simultaneous determination of diminazene diaceturate and phenazone in bulk and dosage forms. The absorbance values of diminazene diaceturate and phenazone aqueous mixture were obtained at 398 nm and 273 nm, respectively. The developed method was proved to be linear over the concentration ranges (2–10) μg/mL and (2.496–12.48) μg/mL for diminazene diaceturate and phenazone, respectively, with good correlation coefficients (not less than 0.997). The detection and quantitation limits were found to be (LOD = 0.63 and 0.48 μg/mL; LOQ = 1.92 and 1.47 μg/mL, resp.). The developed method was employed for stability studies of both drugs under different stress conditions. Diminazene diaceturate was prone to degrade at acidic pH via first-order kinetics. The degradation process was found to be temperature dependent with an activation energy of 7.48 kcal/mole. Photo-stability was also investigated for this drug.

Effect of pod burial, light, and temperature on seed softening in yellow serradella

1999 ◽  
Vol 50 (7) ◽  
pp. 1203 ◽  
Author(s):  
G. B. Taylor ◽  
C. K. Revell
Keyword(s):  
Final Stage ◽  
Soil Surface ◽  
Light Level ◽  
Inhibitory Effect ◽  
Temperature Treatment ◽  
Diurnal Temperature ◽  
Light Levels ◽  
Buried Seeds ◽  
Softening Process ◽  
A Site

Studies were made on the preconditioning stage (which produces latent soft seeds) and the final stage of seed softening in newly ripened seeds of the GEH72-1A accession of yellow serradella (Ornithopus compressus L.). Pods grown at Yelbeni, Western Australia, in 1996 were collected in December and placed on the soil surface or buried at a depth of 0.5 cm at a site near Perth. Other pods were subjected to a gradual diurnal temperature fluctuation of 60/15°C in darkness in a laboratory chamber. Pod samples were taken from the field at intervals from January to June in 1997, and over 336 days from the 60/15°C treatment. Pods were broken into segments and the number of soft seeds determined. Numbers of latent soft seeds were then determined by subjecting residual hard seeds to 7 gradual diurnal temperature cycles of 48/15°C in darkness and retesting for permeability. In a second experiment, seeds preconditioned at the soil surface until 3 March were subjected to a range of light levels in the field in March before testing for permeability. The time taken for seeds to precondition under a range of constant temperatures between 30° and 70°C was determined in a third experiment. Preconditioning commenced early in summer in both surface and buried seeds. All buried seeds that preconditioned completed the softening process to produce about 80% soft seeds, with most seeds softening in March when diurnal temperatures fluctuated between maxima of 45–50°C and minima of 10–20°C. Only 15% of the seeds at the soil surface softened so that relatively few preconditioned seeds completed the softening process. Preconditioning occurred more rapidly than did the completion of softening in the 60/15°C treatment, indicating that this temperature regime was above optimum for the final stage of softening. Reversal of the preconditioning process took place in the field as temperatures declined during May. Effects of reduced temperatures in causing this reversion were confirmed in the laboratory on seeds preconditioned at 60/15°C. The final stage of softening was inhibited in some seeds by light levels as low as 0.3% of daylight, and in all seeds at a light level between 5 and 25%. A close negative linear relation was obtained between the log of the time taken for 50% of seeds to precondition and the constant temperature treatment between 30°C and 70°C, with the rate of preconditioning doubling with every 5.2°C rise in temperature within this range. Although many seeds preconditioned at the soil surface, the main constraint to completion of the seed softening process during autumn was the inhibitory effect of light.

Effect of Solution Content ZnO Nanoparticles on Thermal Stability of Polyvinyl Chloride

2013 ◽  
Vol 4 (2) ◽  
Author(s):  
Farshad Farahbod ◽  
Narges Bagheri ◽  
Fereshteh Madadpour
Keyword(s):  
Thermal Stability ◽  
Chain Length ◽  
Polyvinyl Chloride ◽  
Zno Nanoparticles ◽  
Degradation Process ◽  
Treatment Conditions ◽  
Thermal Degradation Process ◽  
The Stability ◽  
Thermal Stability Of ◽  
Better Than

Today's pipe made of polyvinyl chloride (PVC) is used as basic good in different industries. The thermal stability of the PVC while is filled with ZnO nanoparticles was studied in this paper. This paper show that the stability of the PVC resin mixed with ZnO nanoparticles solution and Sn was better than that of the PVC resin mixed with Sn alone. The UV (ultraviolet)–vis spectra is showed that under certain heat treatment conditions, the PVC samples without ZnO nanoparticles solution embodied relatively high content of the conjugated double bonds with the chain length of about 3–5. However, the content of the conjugated double bond with the chain length of about 6 was greatly increased when the nanoparticles was filled into the PVC resin. This work shows the ZnO nanoparticles could inhibit the thermal degradation process of PVC resin in ionic mechanism.

Sex determination in northern painted turtles: effect of incubation at constant and fluctuating temperatures

1985 ◽  
Vol 63 (11) ◽  
pp. 2543-2547 ◽  
Author(s):  
Lin Schwarzkopf ◽  
Ronald J. Brooks
Keyword(s):  
Sex Determination ◽  
Sex Ratios ◽  
Chrysemys Picta ◽  
Temperature Dependent ◽  
Northern Population ◽  
Painted Turtles ◽  
Threshold Temperatures ◽  
Warm Summer ◽  
Summer Temperatures ◽  
Fluctuating Temperatures

Temperature-dependent sex determination was studied in a northern population of painted turtles (Chrysemys picta) in both laboratory and field. Eggs incubated at constant temperatures of 30 and 32 °C produced females only, whereas those kept at 22, 24, and 26 °C produced males only. Both sexes occurred at 20 and 28 °C. The threshold temperatures (temperatures producing 50% males) were estimated to be 27.5 and 20.0 °C, and were similar to those reported for more southerly populations of C. picta. In both 1983 (a relatively warm summer) and 1984 (an average summer), temperatures in natural nests regularly fluctuated above and below both threshold temperatures. Mean nest temperatures were warmer in 1983 than in 1984, but were not useful to predict nest sex ratios. Mean nest temperatures were not similar to constant temperatures in their effect on sex ratio. Sex ratios in nests could be described best by the total number of hours for which the temperature at each nest was intermediate to the two threshold temperatures. Sex ratios (proportion male) of hatchlings in 1983 and 1984 were similar and female biased (0.12 and 0.13, respectively).

scholarly journals Studies of Dormancy in the Seeds of Subterranean Clover (Trifolium Subterraneum L.) II. The Interaction of Time, Temperature, and Carbon Dioxide During Passage Out of Dormancy

1961 ◽  
Vol 14 (2) ◽  
pp. 173 ◽  
Author(s):  
LAT Ballard
Keyword(s):  
Carbon Dioxide ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Dormancy Breaking ◽  
Temperature Dependent

The dormancy-breaking action of C02 on imbibed seeds of subterranean clover ('1'rijolium 8ubterraneum L.) is temperature dependent, the efficiency falling off sharrlly above 25�C and approaching zero at 30�C. Within the effective temp. erature range the action is rapid, exposure of seeds to CO2 for 6 hr having signifiC!,fit effect.

scholarly journals Thermal pyrolysis characteristics and kinetic analysis of nanofibrillated cellulose/graphene oxide composites

BioResources ◽  
2020 ◽  
Vol 15 (3) ◽  
pp. 4851-4865
Author(s):  
Xia Meng ◽  
Shengdan Wang ◽  
Wenhua Gao ◽  
Wenjia Han ◽  
Lucian A. Lucia
Keyword(s):  
Graphene Oxide ◽  
Degradation Process ◽  
Nanofibrillated Cellulose ◽  
Casting Method ◽  
Evaporation Method ◽  
Pyrolysis Characteristics ◽  
Thermal Pyrolysis ◽  
Thermal Degradation Process ◽  
The One ◽  
Oxide Composites

The fabrication process determines the microstructure and physical properties of material to some extent. In this study nanofibrillated cellulose /graphene oxide (NFC/GO) composites were fabricated by casting and evaporation methods, respectively. The microstructure and thermostability of the composites were investigated. The composites fabricated by the casting method had more uniform layered microstructure than those made by the evaporation method. The thermogravimetry analysis indicated that in the stage of 100 to 220 °C diffusion, the mechanisms of the Ginstling-Brounstein equation (D4) and the one-way transport equation (D1) can be regarded as the most suitable thermal pyrolysis reaction models for the composites made by the casting method and the evaporation method, respectively. However, in the stage of 220 to 380 °C, the two types of composites showed totally different thermal pyrolysis mechanisms. The results manifested that forming methods could indeed affect the microstructure and thermal degradation process of composites.

scholarly journals Thermal degradation of the anthocyanins extracts from jabuticaba peels and red cabbage leaves

2020 ◽  
Vol 16 (6) ◽  
Author(s):  
Priscila Pereira Souza ◽  
Weber Silva Robazza ◽  
Alessandro Cazonatto Galvão
Keyword(s):  
Thermal Degradation ◽  
Degradation Kinetics ◽  
Degradation Process ◽  
Differential Method ◽  
Red Cabbage ◽  
Average Value ◽  
Extraction And Purification ◽  
Different Temperatures ◽  
Thermal Degradation Process ◽  
Experimental Values

Anthocyanins are phenolic compounds with tinctorial capacity. Their successful extraction and purification depends on information associated with their thermal stability. This work presents a study on the degradation kinetics of the anthocyanins in the peels of the jabuticaba fruits and the leaves of red cabbage through assays performed at different temperatures (ranging from 323.15 K to 363.15 K) and degradation times (up to 10 hours for jabuticaba and 30 hours for red cabbage). Total monomeric anthocyanins were determined through the pH differential method. Regarding the extraction, it was observed a larger quantity of anthocyanins from red cabbage extracts, with an average value of 1.3774 mg‧gdb-1, when compared to jabuticaba extracts, with an average value of 1.0479 mg‧gdb-1. The results suggest that the anthocyanins in the red cabbage leaves are much more thermally stable than the anthocyanins in the jabuticaba peels. The experimental assays suggest that the thermal degradation reaction proceeds according to a first-order kinetics model for the anthocyanins in both sources under study. The experimental values were treated according to their thermodynamic relations, which indicated that the thermal degradation process of the evaluated anthocyanins is endothermic and not spontaneous, with similar values of 64.8 kJ‧mol-1 for the red cabbage and 70.2 kJ‧mol-1 for the jabuticaba. 

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