THE EFFECT OF TEMPERATURE ON THE RATE AND VARIATION OF OPERCULAR MOVEMENT IN FUNDULUS DIAPHANUS DIAPHANUS

1947 ◽  
Vol 25d (2) ◽  
pp. 91-95
Author(s):  
Benjamin N. Kropp
Keyword(s):  
Constant Temperature ◽  
Beat Frequency ◽  
Nervous Activity ◽  
Respiratory Movement ◽  
Effect Of Temperature ◽  
Temperature Range ◽  
Sources Of Variation ◽  
Fundulus Diaphanus

The rates of opercular beat of 16 specimens of Fundulus diaphanus diaphanus were recorded over a temperature range from 4.3° to 17.5 °C. in order to determine how this respiratory movement varied with temperature and some of the sources of variation in rate. While the rate of beat varies directly as the temperature, over a period of several hours at any constant temperature continuous recordings of the rate show recurring cycles of rise and fall in beat frequency that are chiefly responsible for the scatter of the observations. Both the duration of a cycle and the limits of rise and fall for each cycle are definitely set by the temperature. The possible dependence of these phenomena upon central nervous activity is discussed.

Acetylene chemisorption at palladium: Effect of temperature and structure of the surface

1984 ◽  
Vol 49 (6) ◽  
pp. 1448-1458
Author(s):  
Josef Kopešťanský
Keyword(s):  
Work Function ◽  
Atomic Hydrogen ◽  
Effect Of Temperature ◽  
Thermally Stable ◽  
Template Effect ◽  
Temperature Range ◽  
Adsorbed Layers ◽  
Different Types ◽  
Adsorption Complexes ◽  
Low Coverage

The effect of temperature and structure of the palladium surfaces on acetylene chemisorption was studied along with the interaction of the adsorbed layers with molecular and atomic hydrogen. The work function changes were measured and combined with the volumetric measurements and analysis of the products. At temperature below 100 °C, acetylene is adsorbed almost without dissociation and forms at least two different types of thermally stable adsorption complexes. Acetylene adsorbed at 200 °C is partly decomposed, especially in the low coverage region. Besides the above mentioned effects, the template effect of adsorbed acetylene was studied in the temperature range from -80° to 25 °C. It has been shown that this effect is a typical phenomenon of the palladium-acetylene system which is not due to surface impurities.

Mitochondrial membrane fluorescence and temperature adaptation in Schistocephalus solidus (Cestoda: Pseudophyllidea)

Parasitology ◽  
1985 ◽  
Vol 90 (1) ◽  
pp. 131-135 ◽  
Author(s):  
R. W. Walker ◽  
J. Barrett
Keyword(s):  
Gasterosteus Aculeatus ◽  
Arrhenius Plot ◽  
Gallus Domesticus ◽  
Temperature Adaptation ◽  
Effect Of Temperature ◽  
Acclimation Temperature ◽  
Membrane Composition ◽  
Mitochondrial Membranes ◽  
Temperature Range ◽  
Schistocephalus Solidus

The fluorescent probe 1-anilino-8-naphthalene suiphonic acid (ANS) was used to investigate the effect of temperature on the physical state of the mitochondrial membranes of adult and larval schistocephalus solzdus together with that of their hosts Gasterosteus aculeatus and Gallus domesticus. Arrhenius plots of ANS/membrane fluorescence for S. solidus plerocercoids was linear over the temperature range 15 to 58 °C, while that for the adult was biphasic with a discontinuity at 39·9 °C. This was interpreted as a physical change which occurred in the adult membrane but not in the plerocercoid membrane and pointed to an alteration in membrane composition during infection. Gasierosteus aculeatus showed a linear Arrhenius plot for membrane fluorescence, irrespective of acclimation temperature. Gallus domesticus showed a discontinuity in the Arrhenius plot for membrane fluorescence at 46·9 °C, outside the normal physiological temperature range.

NQR Relaxation Studies on Halogenomethyl Groups in Halogenoacetates

1998 ◽  
Vol 53 (6-7) ◽  
pp. 480-483 ◽  
Author(s):  
Maria Zdanowska-Fnjczek
Keyword(s):  
Room Temperature ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Effect Of Temperature ◽  
Relaxation Theory ◽  
Temperature Range ◽  
Spin Lattice ◽  
Relaxation Studies

Abstract The effect of temperature on the chlorine NQR spin-lattice relaxation times in CsH(ClH2-CCOO)2 , KH(Cl3 CCOO) 2 and N(CH3)4 H(ClF2CCOO)2 has been studied in the temperature range 77 K to room temperature. The results were discussed on the basis of NQR relaxation theory.

scholarly journals Effect of Temperature, Pressure, and Chemical Composition on the Electrical Conductivity of Schist: Implications for Electrical Structures under the Tibetan Plateau

Materials ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 961 ◽  
Author(s):  
Wenqing Sun ◽  
Lidong Dai ◽  
Heping Li ◽  
Haiying Hu ◽  
Changcai Liu ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
High Pressures ◽  
High Conductivity ◽  
Effect Of Temperature ◽  
The Tibetan Plateau ◽  
Temperature Range ◽  
Electrical Conductivities ◽  
Conductivity Anomalies ◽  
Lower Temperature Range ◽  
Lower Temperature

The experimental study on the electrical conductivities of schists with various contents of alkali ions (CA = K2O + Na2O = 3.94, 5.17, and 5.78 wt.%) were performed at high temperatures (623–1073 K) and high pressures (0.5–2.5 GPa). Experimental results indicated that the conductivities of schist markedly increased with the rise of temperature. Pressure influence on the conductivities of schist was extremely weak at the entire range of experimental temperatures. Alkali ion content has a significant influence on the conductivities of the schist samples in a lower temperature range (623–773 K), and the influence gradually decreases with increasing temperature in a higher temperature range (823–1073 K). In addition, the activation enthalpies for the conductivities of three schist samples were fitted as being 44.16–61.44 kJ/mol. Based on the activation enthalpies and previous studies, impurity alkaline ions (K+ and Na+) were proposed as the charge carriers of schist. Furthermore, electrical conductivities of schist (10−3.5–10−1.5 S/m) were lower than those of high-conductivity layers under the Tibetan Plateau (10−1–100 S/m). It was implied that the presence of schist cannot cause the high-conductivity anomalies in the middle to lower crust beneath the Tibetan Plateau.

Effect of temperature on damage mechanisms and mechanical behaviour of an acrylic-thermoplastic-matrix and glass-fibre-reinforced composite

2020 ◽  
Vol 54 (27) ◽  
pp. 4269-4282
Author(s):  
E Boissin ◽  
C Bois ◽  
J-C Wahl ◽  
T Palin-Luc
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Polymer Matrix ◽  
Mechanical Response ◽  
Polymer Matrix Composites ◽  
Effect Of Temperature ◽  
Matrix Composites ◽  
Service Temperature ◽  
Damage Mechanisms ◽  
Temperature Range

The mechanical response of polymer matrix composites exhibits a temperature dependency even if the service temperature range is lower than the glass transition temperature of the polymer matrix. This dependency is mainly due to the temperature effect on the mechanical behaviour of the polymer matrix. However, the micro- and meso-structures driving the composite anisotropy and local stress distribution play an essential role regarding the effect of temperature on damage mechanisms specific to reinforced polymers. There are few data in the literature on the sensitivity to temperature of damage mechanisms and scenarios of polymer matrix composites regardless of loading type. In this paper, after a synthetic literature review of the effect of temperature on polymers and polymer composites, several complementary tests are proposed to analyse the temperature effect on damage mechanisms undergone by laminated composites under in-plane quasi static loadings. These tests are applied to an acrylic-thermoplastic composite reinforced by glass fibres in its service temperature range of –20℃ to 60℃. The results show that the testing temperature has a significant impact on the mechanical response and damage mechanisms of the composite material in the selected temperature range, which is markedly lower than the glass transition temperature (around 100℃). While the temperature rise generates a gradual decrease in matrix stiffness and strength, the increase in matrix ductility associated to the stress heterogeneity in the composite microstructure produces a rise in the transverse cracking threshold and removes this damage mode during quasi-static tensile tests when the temperature shifts from 15℃ to 40℃.

THERMAL STUDIES ON ASBESTOS: I. EFFECT OF TEMPERATURE AND TIME OF HEATING ON LOSS IN WEIGHT AND RESORPTION OF MOISTURE

1941 ◽  
Vol 19b (2) ◽  
pp. 49-55
Author(s):  
D. Wolochow ◽  
W. Harold White
Keyword(s):  
Rapid Method ◽  
Thermal Studies ◽  
Effect Of Temperature ◽  
Chrysotile Asbestos ◽  
Prolonged Heating ◽  
Temperature Range ◽  
Free Moisture

Heating a chrysotile asbestos mill fibre has shown that in the approximate temperature range of 500 to 700 °C. the loss in weight depends on both the time and temperature. At other temperatures the loss is practically independent of the time.Prolonged heating at about 490 °C. expelled about 25%, and at 510 °C. about 50%, of the combined water. Complete dehydration occurred on prolonged heating at about 580 °C., but only above 700 °C. was the loss in weight rapid.On the basis of the data obtained on the resorption of moisture it is suggested that heating for half an hour at 215 °C. would be a more accurate and rapid method for determining free moisture than that commonly employed.

scholarly journals Effect of pretreatments on drying behavior of eggplant

2019 ◽  
Vol 17 (1) ◽  
pp. 105-109
Author(s):  
Md Junaeid Khan ◽  
Farjana Yeasmin ◽  
Md Nazrul Islam ◽  
Raju Ahmmed ◽  
Pabitra Chandra Das ◽  
...  
Keyword(s):  
Constant Temperature ◽  
Rate Constant ◽  
Hot Water ◽  
Effect Of Temperature ◽  
Constant Thickness ◽  
Drying Rate ◽  
Fresh Sample ◽  
Drying Time ◽  
Preservation Method ◽  
Drying Behavior

Eggplant is a familiar and admired vegetable in Bangladesh. It is a highly perishable vegetable and cannot be preserved long. Drying is an ancient preservation method used to extend shelf-life of fruits and vegetables. Different Pretreatments may affect the drying kinetics of foods. A study was conducted to evaluate how pretreatments affect the drying behavior of eggplant. Proximate composition of fresh eggplant was analyzed. The samples of constant thickness (8 mm) were dried at 50°C, 55°C and 60°C to determine the effect of temperature on drying rate constant, while for determining the effect of thickness on rate constant, eggplant slices of 4, 6 and 8 mm thicknesses were dried at a constant temperature of 55°C. It was observed that, drying rate decreased with the increase in thickness and the index ‘n’ was found to be 0.89 at 55°C. Under similar drying condition at constant thickness (8 mm), drying time showed an inverse relationship with temperature. The activation energy (Ea) was calculated as 3.242 Kcal/g-mole. Eggplant slices having the highest thickness (8 mm) were blanched at 70°C, 75°C and 80°C for 1, 2 and 2.5 minutes, respectively using hot water bath to determine the effective blanching time and temperature. It was observed that the samples blanched at 75°C and 80°C for 2 minute were enough to inactivate the enzymes. Pretreated (blanched, sulphited and blanched plus sulphited) eggplant slices having constant thickness (8 mm) were dried at constant temperature of 55°C. The drying time was influenced by pretreatments. The highest drying rate was observed for eggplant slices with blanched plus sulphited (5% KMS solution) samples while eggplant slices with 5%KMS solution dipped for 10 minutes showed the lowest drying rate. In case of fresh slices, drying time was lower than blanched and sulphited samples but higher than blanched plus sulphited samples. Pretreatment was also found effective on the color changes (preservation or degradation). Blanching gave a bright color compared to fresh sample but less bright compared to sulphited samples. In case of SO2 retention, blanched plus sulphited sample showed higher retention than sulphited sample. Sulphited sample retains 44.8 ppm SO2/100g of sulphited sample, while the blanched plus sulphited sample retains 280 ppm SO2/100 g of blanched plus sulphited sample. J. Bangladesh Agril. Univ. 17(1): 105–109, March 2019

scholarly journals Revisiting nucleosynthesis in globular clusters

2017 ◽  
Vol 608 ◽  
pp. A28 ◽  
Author(s):  
N. Prantzos ◽  
C. Charbonnel ◽  
C. Iliadis
Keyword(s):  
Nuclear Reaction ◽  
Constant Temperature ◽  
Globular Clusters ◽  
Chemical Properties ◽  
Reaction Network ◽  
Stellar Populations ◽  
Reaction Rates ◽  
Temperature Range

Context. Motivated by recent reports concerning the observation of limited enrichment in He but excess K in stars of globular clusters, we revisit the H-burning conditions that lead to the chemical properties of multiple stellar populations in these systems. Aims. In particular, we are interested in correlations of He and K with other elements, such as O, Na, Al, Mg and Si, reported in stars of NGC 2808. Methods. We performed calculations of nucleosynthesis at constant temperature and density, exploring the temperature range of 25 to 200 × 106 K (25 to 200 MK), using a detailed nuclear reaction network and the most up-to-date nuclear reaction rates. Results. We find that Mg is the most sensitive “thermometer” of hydrostatic H-burning conditions, pointing to a temperature range of 70–80 MK for NGC 2808, while He is a lesser – but not negligible – constraint. Potassium can be produced at the levels reported for NGC 2808 at temperatures >180 MK and Si at T > 80 MK. However, in the former temperature range Al and Na are totally destroyed and no correlation can be obtained, in contrast to the reported observations. None of the putative polluter sources proposed so far seem to satisfy the ensemble of nucleosynthesis constraints.

THE EFFECT OF TEMPERATURE ON THE CRITICAL OXYGEN PRESSURE FOR HEART-BEAT FREQUENCY IN EMBRYOS OF ATLANTIC SALMON AND SPECKLED TROUT

1942 ◽  
Vol 20d (1) ◽  
pp. 1-12 ◽  
Author(s):  
Kenneth C. Fisher
Keyword(s):  
Atlantic Salmon ◽  
Partial Pressure ◽  
Oxygen Pressure ◽  
Critical Pressure ◽  
Beat Frequency ◽  
Heart Beat ◽  
Effect Of Temperature ◽  
Limiting Factor ◽  
Partial Pressure Of Oxygen ◽  
Critical Oxygen

Intact embryos of speckled trout and Atlantic salmon were exposed to solutions of oxygen and nitrogen in distilled water. It was observed that as the partial pressure of oxygen was reduced a pressure was found below which the frequency of the heart-beat was not maintained at the normal level characteristic of higher partial pressures of oxygen. A "critical" partial pressure of oxygen for heart-beat frequency can therefore be said to exist. Data have been obtained from which its value at five different temperatures can be determined. The critical pressures for the two organisms are similar, rising from approximately 3 to 5 mm. of mercury at 1.5 °C. to 40 to 50 mm. of mercury at 20 °C. Possible mechanisms leading to the establishment of a critical oxygen partial pressure are discussed. It seems likely that diffusion is not the limiting factor in these preparations so that the critical pressure, and its temperature coefficient, must be the property of the intracellular respiratory systems concerned. The finding that the logarithm of the critical partial pressure can be represented as a linear function of the reciprocal of the absolute temperature is consistent with this view. Temperature exercises a more pronounced effect on the critical oxygen pressure of the pacemaking process, than it does on the over-all velocity of that process as indicated by the normal frequency of the heart. It is concluded that the critical pressure is a characteristic of the chemical systems in the pace-making cells of the heart.

Effect of Temperature on Ozone Cracking of Butyl Rubbers

1968 ◽  
Vol 41 (5) ◽  
pp. 1294-1299 ◽  
Author(s):  
A. N. Gent ◽  
H. Hirakawa
Keyword(s):  
Crack Growth ◽  
Ozone Concentration ◽  
Effect Of Temperature ◽  
Segmental Mobility ◽  
Temperature Range ◽  
Styrene Copolymers ◽  
The Difference ◽  
Rates Of Growth ◽  
Rate Controlling Step ◽  
Butadiene Styrene

Abstract Rates of growth of single ozone cracks have been measured for vulcanizates of two butyl rubbers over the temperature range of 20-160° C. Over most of this range the rates are quantitatively related to the segmental mobility of the polymer and depend upon temperature in accord with the appropriate form of the WLF relation. The rates are also proportional to the concentration of ozone. It is therefore concluded that diffusion of ozone into the polymer before reaction is the rate-controlling step. This is contrasted with the behavior of butadiene styrene copolymers, for which rates of crack growth are also quantitatively related to the segmental mobility, but the rates are somewhat larger at equivalent mobilities and the dependence upon ozone concentration is smaller. The difference is attributed to different penetration distances before reaction in polymers containing low and high densities of reactive sites.

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