Leaf Temperature Kinetics Measure Plant Adaptation to Extreme High Temperatures

1996 ◽  
Vol 23 (4) ◽  
pp. 445 ◽  
Author(s):  
SN Shabala
Keyword(s):  
Ambient Temperature ◽  
High Temperatures ◽  
Leaf Temperature ◽  
Rate Of Change ◽  
Plant Age ◽  
Leading Role ◽  
Regulatory Systems ◽  
Adaptive Ability ◽  
Critical Ambient Temperature ◽  
Simple Equations

Leaf temperature kinetics were studied as a function of the rate of change of ambient temperature (Vt), light conditions, plant age, and genotypic and species diversity for Zea mays, Cucumis sativus, Lycopersicon esculentum, Phaseolus vulgaris, Beta vulgaris, Cucurbita pepo and Raphanus sativus. Ambient temperature was varied from 26 to 60�C at rates from 0.5 to 8�C/min. Leaf-air temperature differences (LATD) were registered with differential copper-constantan thermocouples. As the ambient temperature rose LATD increased because stomata had been closed in darkness. Still in the darkness, at some critical ambient temperature stomata opened and the leaf temperature reduced dramatically as result of stomatal transpiration. The critical temperature is strongly dependent upon Vt. Simple equations for the calculation of a threshold of plant temperature sensitivity and of a time constant for stomatal signal transduction have been obtained. These parameters show a high correlation with plant heat tolerance both in genotypic and species aspects. This is consistent with the idea that temporal organisation of plant regulatory systems plays a leading role in evolution and in adaptation to extreme environmental conditions. Both characteristics measured tend to change with plant age. It is concluded that the measurement of leaf temperature kinetics is a very convenient procedure for estimating plant adaptive ability to high temperatures.

Change in the Properties of a Lead-acid Battery Depending on the Cycling Speed and the Ambient Temperature

2021 ◽  
Vol 105 (1) ◽  
pp. 119-134
Author(s):  
Jana Zimáková ◽  
Petr Baca ◽  
Martin Langer ◽  
Tomáš Binar
Keyword(s):  
Ambient Temperature ◽  
High Temperatures ◽  
Room Temperature ◽  
Lead Acid Battery ◽  
Ambient Temperatures ◽  
Lead Acid Batteries ◽  
Temperature Dependences ◽  
Cycling Speed ◽  
Lead Acid

This work deals with lead-acid batteries, their properties and individual types that are available on the market. The temperature dependences of the battery parameters at different ambient temperatures and at different discharging and charging modes are measured. 6 batteries are tested at different charging currents, which provides information about their behavior both during discharge and at the time of charging. During the experiments, testing is not only performed at room temperature, but the batteries are also exposed to high temperatures up to 75 °C.

Consideration of the Cross-Anisotropy of Different Materials of the Asphalt Surface Layer and Temperature to Determine Pavement Responses

2021 ◽  
Vol 13 (1) ◽  
pp. 140-151
Author(s):  
Minrui Guo ◽  
Xinglin Zhou
Keyword(s):  
Surface Layer ◽  
High Temperatures ◽  
Low Temperatures ◽  
Compressive Strain ◽  
Fatigue Cracking ◽  
Element Model ◽  
Rate Of Change ◽  
Temperature Relationship ◽  
The Cross ◽  
Cross Anisotropy

The effects of the cross-anisotropy of different materials of the asphalt surface layer and the depth-temperature relationship on pavement responses and damage are investigated. A three-dimensional Finite-Element Model (FEM) of the pavement, which considers the depth-temperature relationship of the surface layer under moving tire load, is developed. Pavement damage models are established to evaluate the damage ratio for primary rutting and fatigue cracking. The results show that the compressive strain at the bottom of the surface layer increases as the temperature increases, and the cross-anisotropy (n-value) decreases, indicating that a decrease in the horizontal modulus of different materials of the surface layer increases the damage ratio for primary rutting at high temperatures. The tensile strain at the bottom of the surface layer declines as the n-value increases to 1. For the same change in the n-value, the rate of change of the damage ratio for fatigue cracking is greater at low temperatures than at high temperatures, demonstrating that the number of allowable load repetitions is more sensitive at low temperatures. In addition, the effect of cross-anisotropy and temperature on the vertical stress are larger on the top of the base than in the subbase and subgrade.

scholarly journals Transient Analysis of Thermal Treatment Processes Carburizing and Nitriding of Steel Components by Numerical Modeling and Simulation

2019 ◽  
Vol 9 (2) ◽  
pp. 2584-2593
Keyword(s):  
Differential Equation ◽  
Numerical Modeling ◽  
Ambient Temperature ◽  
Modeling And Simulation ◽  
Geometric Dimension ◽  
Rate Of Change ◽  
Critical Parameters ◽  
Numerical Modeling And Simulation ◽  
Linear Differential ◽  
Energy Balance Approach

The purpose of carburizing, nitriding and carbonitriding is to increase the strength of components. Elements such as carbon, nitrogen and carbon-nitride are diffused into the components at high temperature convective environment. The amount of diffusion is to be regulated by controlling the temperature and time of diffusion. Time and temperature of process govern diffusion rate and strength of the component. Numerical modeling is applied by energy balance approach i.e., equating rate of change of energy is equal to energy transferred by conduction, convection and radiation. By non dimensionalising relations for the mentioned critical parameters were obtained. The phenomenon of convection, radiation and conduction are taken together for the purpose of numerical modeling. Variation of temperature and depth of diffusion of component for the taken components i.e., sphere and cube was plotted in transient state. For both numerical analysis and simulation the boundary conditions i.e., for carburization the ambient temperature is 9500C with carbon monoxide as the carburizing agent and for nitriding the ambient temperature is 5300C with nitrogen as nitriding agent and the component taken is of steel which is initially at room temperature were taken. Results obtained from numerical modeling and simulation were compared with each other and observed that in both analyses the variation of temperature with time and depth of diffusion is almost linear. Final differential equation obtained in numerical modeling is a single order non linear differential equation which is solved in MATLAB using finite difference approach. Data obtained from MATLAB were plotted for variation of surface temperature and geometric dimension with respect to time.

scholarly journals Effect of milk chocolate supplementation with lyophilised Lactobacillus cells on its attributes

2010 ◽  
Vol 28 (No. 5) ◽  
pp. 392-406 ◽  
Author(s):  
D. Żyżelewicz ◽  
E. Nebesny ◽  
I. Motyl ◽  
Z. Libudzisz
Keyword(s):  
Ambient Temperature ◽  
High Temperatures ◽  
Functional Food ◽  
Lactobacillus Casei ◽  
Probiotic Bacteria ◽  
Live Cells ◽  
Bacterial Cells ◽  
Bacterial Strains ◽  
Milk Chocolate ◽  
Live Bacterial Cells

Manufacturing of novel foodstuffs supplemented with live probiotic bacteria has recently been intensively investigated. The supplementation of confectionery with probiotics is troublesome since some unit technological processes are conducted at high temperatures and the products are usually stored at ambient temperature. Our group has developed a method of the production of milk chocolate, sweetened with either sucrose or isomalt and aspartame, containing 32, 36, or 40 g/100 g fat, and supplemented with live cells of probiotic bacterial strains: Lactobacillus casei and paracasei. This new milk chocolate displayed the same sensory properties as the reference, probiotic-free chocolate. The number of live bacterial cells was maintained at the functional level of 10<sup>6</sup> &divide; 10<sup>8</sup> cfu/g after keeping for 12 months irrespective of the temperature. The highest number of live probiotic bacteria survived in the chocolate kept at 4&deg;C. Thus the product can be regarded as functional food.

scholarly journals The Stability of Icosahedral Cd-Yb

2003 ◽  
Vol 805 ◽  
Author(s):  
Günter Krauss ◽  
Sofia Deloudi ◽  
Andrea Steiner ◽  
Walter Steurer ◽  
Amy R. Ross ◽  
...  
Keyword(s):  
Low Temperature ◽  
Ambient Temperature ◽  
Mechanical Stress ◽  
Single Crystals ◽  
High Temperatures ◽  
Low Temperatures ◽  
Ambient Pressure ◽  
X Ray Diffraction ◽  
X Ray ◽  
The Stability

ABSTRACTThe stability of single-crystalline icosahedral Cd-Yb was investigated using X-ray diffraction methods in the temperature range 20 K ≤ T ≤ 900 K at ambient pressure and from ambient temperature to 873 K at about 9 GPa. Single-crystals remain stable at low temperatures and in the investigated HP-HT-regime. At high temperatures and ambient pressure, the quasicrystal decomposes. The application of mechanical stress at low temperatures yields to the same decomposition, the formation of Cd. A reaction of icosahedral Cd-Yb with traces of oxygen or water causing the decomposition seems reasonable, but a low-temperature instability of this binary quasi-crystal cannot be ruled out totally.

scholarly journals EFFECT OF AMBIENT TEMPERATURE ON THERMAL RESPONSES TO DRUGS

1958 ◽  
Vol 36 (1) ◽  
pp. 1243-1249 ◽  
Author(s):  
Irving Shemano ◽  
Mark Nickerson
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Ambient Temperature ◽  
Ambient Temperatures ◽  
The Central Nervous System ◽  
Critical Ambient Temperature

Thermal responses to a variety of drugs have been investigated at various ambient temperatures, using unanesthetized rats, either lightly restrained or paralyzed with tubocurarine. The results indicate that ambient temperature is a major factor determining thermal responses to many drugs. Experiments on lightly restrained rats demonstrated that the critical ambient temperature, the temperature above which hyperthermia is evoked and below which hypothermia is produced, is about 30 °C (in the thermoneutral range) for Hydergine, ergotamine, LSD-25, and serotonin. The critical ambient temperature for chlorpromazine is approximately 36 °C, and that for 2,4-dinitrophenol, 20 °C. Reserpine produced a consistent hypothermia at 23 °C, but somewhat inconsistent effects at ambient temperatures above this up to 39 °C. Complete curarization abolished the hypothermic effects of all the above agents except chlorpromazine. The production of both hyperthermia and hypothermia by most of the drugs studied suggests that they influence temperature-regulating centers of the central nervous system.

High temperature mechanical properties of steel bars available in Pakistan

2018 ◽  
Vol 9 (3) ◽  
pp. 203-221 ◽  
Author(s):  
Muhammad Masood Rafi ◽  
Abdul Basit Dahar ◽  
Tariq Aziz
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Ambient Temperature ◽  
High Temperatures ◽  
Elevated Temperatures ◽  
Experimental Testing ◽  
Local Market ◽  
Content Type ◽  
Yield Plateau ◽  
Steel Bars

Purpose The purpose of this paper is to present the results of experimental testing of steel rebars at elevated temperatures. Three types of bars available in the local market in Pakistan were used. These data are not available in Pakistan. Design/methodology/approach Three types of bars were used, which included cold-twisted ribbed (CTR), hot-rolled deformed (HRD) and thermo-mechanically treated (TMT) bars. The diameter of the bar of each type was 16 mm. The bars were heated in an electrical furnace at temperatures which were varied from 100°C to 900°C in increment of 100°C. Bars of each type were also tested at ambient temperature as control specimens. The change of strength, strain and modulus of elasticity of the bars at high temperatures were determined. Findings The mechanical properties of the bars were nearly unaffected by the temperatures up to 200°C. CTR bars did not show yield plateau and strain hardening both at ambient and high temperatures. The high temperature yield strength and elastic modulus for all the three types of bars were similar at all temperatures. The yield plateau of both the HRD and TMT bars disappeared at temperatures greater than 300°C. The ultimate strength at high temperature of the HRD and TMT bars was also similar. The behaviours of the HRD and TMT bars changed to brittle beyond 400°C as compared to their behaviours at ambient temperature. The CTR bars exhibited ductile characteristics at failure at all the exposure temperatures relative to their behaviour at ambient temperature. Research limitations/implications The parameters of the paper included the rebar type and heating temperature and the effects of temperature on strength and stiffness properties of the steel bars. Practical implications Building fire incidents have increased in Pakistan. As reinforced concrete (RC) buildings exist in the country in significant numbers, the data related to elevated temperature properties of steel is required. These data are not available in Pakistan presently. The presented paper aims at providing this information for the design engineers to enable them to assess and increase fire resistance of RC structural members. Originality/value The presented paper is unique in its nature in that there is no published contribution to date, to the best of authors’ knowledge, which has been carried out to assess the temperature-dependent mechanical properties of steel reinforcing bars available in Pakistan.

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