An experimental study on the effect of elevated temperature on the heterotrophic and autotrophic food resources of aquatic insects in a forested stream

1986 ◽  
Vol 64 (11) ◽  
pp. 2457-2466 ◽  
Author(s):  
Robert S. Rempel ◽  
John C. H. Carter
Keyword(s):  
Organic Matter ◽  
Elevated Temperature ◽  
Aquatic Insects ◽  
Elevated Temperatures ◽  
Food Resources ◽  
Decay Rates ◽  
Effect Of Temperature ◽  
Stone Surface ◽  
Organic Layers ◽  
Autotrophic Activity

The effect of temperature on the heterotrophic and autotrophic food resources of aquatic insects was investigated in outdoor experimental channels and in the laboratory. Elevated temperatures in outdoor channels resulted in accelerated decay rates and accumulation of organic layers on introduced tiles. Heterotrophic activity (substrate respiration) increased with temperature in the laboratory for leaf strips, flocculent organic matter, and stone surface organic layers. Autotrophic activity (substrate photosynthesis) was greater in the laboratory for flocculent detritus (per milligram ash-free dry weight) than for stone surface organic layers. These results indicate that the primary food resources of shredder, collector, and scraper functional guilds are enhanced by elevated temperature, but also suggest that coarse particulate organic matter may disappear from the stream more quickly. The results also point out that substantial autotrophic activity occurs within flocculent organic detritus.

scholarly journals Acidovorax citrulli is sensitive to elevated temperatures during early stages of watermelon seed germination

2020 ◽  
Vol 48 (1) ◽  
pp. 11-20
Author(s):  
Mei Zhao ◽  
Ron Walcott
Keyword(s):  
Elevated Temperature ◽  
Seed Germination ◽  
Elevated Temperatures ◽  
Transmitted Disease ◽  
Effect Of Temperature ◽  
Crop Species ◽  
Inoculum Concentration ◽  
Bacterial Fruit Blotch ◽  
Acidovorax Citrulli ◽  
Germinating Seeds

Bacterial fruit blotch (BFB), caused by Acidovorax citrulli, is a seed-transmitted disease of cucurbit crop species. During seed-to-seedling transmission of BFB, A. citrulli initially grows as a saprophyte on germinating seeds and subsequently switches to a pathogenic mode. We investigated the effect of temperature on A. citrulli colonisation of germinating watermelon seeds. Seeds were vacuum-infiltrated with 106 CFU/ml A. citrulli, germinated at 28°C and 100% relative humidity, and transferred to 40°C at different times. Mean BFB incidence was significantly lower for seeds that were sown at 28°C and transferred to 40°C three days after sowing (DAS), compared with seeds incubated constantly at 28°C. Seeds showed reduced mean BFB transmission percentages when transferred from 28 to 40°C at 3 DAS, regardless of initial A. citrulli concentration. The effect of increased temperature on BFB seedling transmission was reversible regardless of the initial A. citrulli inoculum concentration. Furthermore, the A. citrulli population on germinating watermelon seedlings that were transferred from 28 to 40°C at 3 DAS was significantly lower than seedlings maintained at 28°C. We conclude that A. citrulli cells associated with germinating watermelon seeds are more sensitive to elevated temperature during the first 3 DAS relative to the later days.

Effect of temperature on the heart in the alligator

1960 ◽  
Vol 198 (4) ◽  
pp. 861-863 ◽  
Author(s):  
Charles G. Wilber
Keyword(s):  
Heart Rate ◽  
Elevated Temperature ◽  
Elevated Temperatures ◽  
Well Being ◽  
Effect Of Temperature ◽  
Optimal Temperature ◽  
General Behavior ◽  
Colonic Temperature

Electrocardiograms were taken on 12 alligators, 18–30 inches in length. Some were exposed to elevated temperatures; the resulting ECG's were compared with controls obtained at 22°C, which were as follows: rate, 40/min.; P-R, 0.4 seconds; Q-T, 0.6 seconds; T, 0.24 second, 0.05 mv; QRS, 0.04 second. Heart rate increased with increased colonic temperature. At 34°C there was marked increase in variability of rate. Above 40°C the heart became irregular and was damaged irreversibly. Duration of T decreased with elevated temperature to about 33°C above which T was prolonged. Optimal temperature for the alligator in terms of tolerance and general behavior is between 32°C and 35°C, with a critical maximum of 38°C. Slightly above that temperature the heart became disorganized. The present results suggest that the alligator's temperature preferendum is sound with respect to cardiac well being.

scholarly journals Study on Tensile Properties of CFRP Plates under Elevated Temperature Exposure

Materials ◽  
2019 ◽  
Vol 12 (12) ◽  
pp. 1995 ◽  
Author(s):  
Yongxin Yang ◽  
Yanju Jiang ◽  
Hongjun Liang ◽  
Xiaosan Yin ◽  
Yue Huang
Keyword(s):  
Tensile Strength ◽  
Elastic Modulus ◽  
Elevated Temperature ◽  
Tensile Properties ◽  
Failure Mode ◽  
Elevated Temperatures ◽  
Strain Curve ◽  
Effect Of Temperature ◽  
Temperature Exposure ◽  
The Impact

Elevated temperature exposure has a negative effect on the performance of the matrix resin in Carbon Fiber Reinforced Plastics (CFRP) plates, whereas limited quantitative research focuses on the deteriorations. Therefore, 30 CFRP specimens were designed and tested under elevated temperatures (10, 30, 50, 70, and 90 °C) to explore the degradations in tensile properties. The effect of temperature on the failure mode, stress-strain curve, tensile strength, elastic modulus and elongation of CFRP plates were investigated. The results showed that elevated temperature exposure significantly changed the failure characteristics. When the exposed temperature increased from 10 °C to 90 °C, the failure mode changed from the global factures in the whole CFRP plate to the successive fractures in carbon fibers. Moreover, with temperatures increasing, tensile strength and elongation of CFRP plates decreases gradually while the elastic modulus shows negligible change. Finally, the results of One-Way Analysis of Variance (ANOVA) show that the degradation of the tensile strength of CFRP plates was due to the impact of elevated temperature exposure, rather than the test error.

Fatigue Strength of Maraging Steel at Elevated Temperatures

2008 ◽  
Vol 385-387 ◽  
pp. 161-164 ◽  
Author(s):  
T. Iwamoto ◽  
Norio Kawagoishi ◽  
Nu Yan ◽  
Eiji Kondo ◽  
Kazuhiro Morino
Keyword(s):  
Elevated Temperature ◽  
Fatigue Strength ◽  
Maraging Steel ◽  
Fracture Mechanism ◽  
Elevated Temperatures ◽  
Surface Oxidation ◽  
Fatigue Tests ◽  
Age Hardening ◽  
Effect Of Temperature ◽  
Rotating Bending Fatigue

Rotating bending fatigue tests were carried out to investigate the effects of temperature on the fatigue strength and the fracture mechanism of an 18 % Ni maraging steel at room and elevated temperatures of 473K and 673K. Fatigue strength was higher at elevated temperatures than at room temperature, though static strength was decreased by softening at elevated temperature. There was no effect of temperature on crack morphology and fracture mechanism. On the other hand, during fatigue process at elevated temperature, the specimen was age-hardened and the specimen surface was oxide. That is, the increase in fatigue strength at elevated temperature was mainly caused by the increase in hardness due to age-hardening and suppression of a crack initiation due to surface oxidation.

Effect of Elevated Temperature Exposures on Shear Properties of Sheathing Panels

2020 ◽  
Vol 70 (1) ◽  
pp. 115-121
Author(s):  
Rajendra Soti ◽  
Cody Knight ◽  
Shanmathi Mageshwar ◽  
Srikar D. Valluri ◽  
Arijit Sinha
Keyword(s):  
Shear Strength ◽  
Elevated Temperature ◽  
Shear Modulus ◽  
Exposure Time ◽  
Elevated Temperatures ◽  
Oriented Strand Board ◽  
Effect Of Temperature ◽  
Structural Wall ◽  
Timber Frame ◽  
Existing Structures

Abstract Structural wall sheathing such as oriented strand board (OSB) and plywood have been heavily used in residential and commercial timber frame construction. The response of these wood-based composites under elevated temperatures between 100°C and 200°C (herein referred to as elevated temperatures) and exposure time needs to be characterized to assess residual strength of the materials in the existing structures. The main objective of this work is to study the effect of temperature and exposure time on shear strength and shear modulus of plywood and OSB. A total of 110 test specimens was tested in shear after exposure to five different temperatures and two exposure durations, followed by cooling to ambient temperature. The results indicated that the plywood and OSB behaved differently after exposure to elevated temperatures and exposure duration. Plywood showed a consistent degradation of shear strength with elevated temperature and time, while OSB did not exhibit a clear picture of thermal degradation. The results further indicated that the shear modulus of plywood and OSB remained unaffected after exposure to elevated temperatures.

scholarly journals A Constitutive Relation Based on the Johnson–Cook Model for Ti-22Al-23Nb-2(Mo, Zr) Alloy at Elevated Temperature

Crystals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 754
Author(s):  
Yanju Wang ◽  
Duo Zhou ◽  
Yi Zhou ◽  
Aixue Sha ◽  
Huaxing Cheng ◽  
...  
Keyword(s):  
Elevated Temperature ◽  
Flow Stress ◽  
Constitutive Relation ◽  
Deformation Behavior ◽  
Elevated Temperatures ◽  
Peak Stress ◽  
Testing Temperature ◽  
Effect Of Temperature ◽  
Different Temperatures ◽  
Zr Alloy

Although several schemes have been proposed to modify the classical Johnson–Cook (J-C) model, the effect of temperature on the flow stress of materials at different temperatures has not been clarified. In the current study, to investigate the deformation behavior of Ti-22Al-23Nb-2(Mo, Zr) alloy at different temperatures, uniaxial tension experiments were performed at both room (RT, 28 °C) and elevated temperatures, and a modified J-C model was developed to describe the temperature-dependent plastic flow. In tensile experiments, Ti2AlNb-based alloy showed a continuous work hardening until reaching the ultimate strength at RT, while an apparent drop appeared in the flow stress after the peak stress at elevated temperature. Moreover, the experimental peak stress significantly depends on the testing temperature. To correctly describe the different variations of flow stresses at different temperatures, a parameter, S, which represents the softening behavior of flow stress, is integrated into the classical J-C model. In addition, the applicability and validity of the proposed J-C model were verified by calibration with experimental curves of different temperatures. On the other hand, the fractography of post-test specimens was examined to interrupt the increased fracture brittleness of Ti2AlNb-based alloy at elevated temperatures. The proposed constitutive relation based on the J-C model is applicable to predict the deformation behavior of other Ti2AlNb-based alloys at different temperatures.

Effect of Temperature, Velocity Gradient and I.V. Heparin on in Vitro Blood Coagulation and Platelet Aggregation

1967 ◽  
Vol 17 (01/02) ◽  
pp. 112-119 ◽  
Author(s):  
L Dintenfass ◽  
M. C Rozenberg
Keyword(s):  
Blood Coagulation ◽  
Velocity Gradient ◽  
Elevated Temperatures ◽  
Morphological Changes ◽  
Effect Of Temperature ◽  
Clotting Time ◽  
Progressive Change ◽  
Aggregation Of Platelets ◽  
Microscopic Techniques

SummaryA study of blood coagulation was carried out by observing changes in the blood viscosity of blood coagulating in the cone-in-cone viscometer. The clots were investigated by microscopic techniques.Immediately after blood is obtained by venepuncture, viscosity of blood remains constant for a certain “latent” period. The duration of this period depends not only on the intrinsic properties of the blood sample, but also on temperature and rate of shear used during blood storage. An increase of temperature decreases the clotting time ; also, an increase in the rate of shear decreases the clotting time.It is confirmed that morphological changes take place in blood coagula as a function of the velocity gradient at which such coagulation takes place. There is a progressive change from the red clot to white thrombus as the rates of shear increase. Aggregation of platelets increases as the rate of shear increases.This pattern is maintained with changes of temperature, although aggregation of platelets appears to be increased at elevated temperatures.Intravenously added heparin affects the clotting time and the aggregation of platelets in in vitro coagulation.

scholarly journals Effect of Elevated Temperature on Mechanical Properties of High-Volume Fly Ash-Based Geopolymer Concrete, Mortar and Paste Cured at Room Temperature

Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1473
Author(s):  
Jun Zhao ◽  
Kang Wang ◽  
Shuaibin Wang ◽  
Zike Wang ◽  
Zhaohui Yang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Elevated Temperature ◽  
Fly Ash ◽  
Residual Strength ◽  
Elevated Temperatures ◽  
High Volume ◽  
Sem Analysis ◽  
Geopolymer Concrete ◽  
Ordinary Concrete ◽  
Exposure Temperature

This paper presents results from experimental work on mechanical properties of geopolymer concrete, mortar and paste prepared using fly ash and blended slag. Compressive strength, splitting tensile strength and flexural strength tests were conducted on large sets of geopolymer and ordinary concrete, mortar and paste after exposure to elevated temperatures. From Thermogravimetric analyzer (TGA), X-ray diffraction (XRD), Scanning electron microscope (SEM) test results, the geopolymer exhibits excellent resistance to elevated temperature. Compressive strengths of C30, C40 and C50 geopolymer concrete, mortar and paste show incremental improvement then followed by a gradual reduction, and finally reach a relatively consistent value with an increase in exposure temperature. The higher slag content in the geopolymer reduces residual strength and the lower exposure temperature corresponding to peak residual strength. Resistance to elevated temperature of C40 geopolymer concrete, mortar and paste is better than that of ordinary concrete, mortar and paste at the same grade. XRD, TGA and SEM analysis suggests that the heat resistance of C–S–H produced using slag is lower than that of sulphoaluminate gel (quartz and mullite, etc.) produced using fly ash. This facilitates degradation of C30, C40 and C50 geopolymer after exposure to elevated temperatures.

Effects of Elevated Temperatures on the Compressive Strength of HFCC

2011 ◽  
Vol 261-263 ◽  
pp. 416-420 ◽  
Author(s):  
Fu Ping Jia ◽  
Heng Lin Lv ◽  
Yi Bing Sun ◽  
Bu Yu Cao ◽  
Shi Ning Ding
Keyword(s):  
Compressive Strength ◽  
Elevated Temperature ◽  
Fly Ash ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Relative Strength ◽  
Ordinary Concrete ◽  
Residual Compressive Strength ◽  
Fly Ash Concrete ◽  
The Relationship

This paper presents the results of elevated temperatures on the compressive of high fly ash content concrete (HFCC). The specimens were prepared with three different replacements of cement by fly ash 30%, 40% and 50% by mass and the residual compressive strength was tested after exposure to elevated temperature 250, 450, 550 and 650°C and room temperature respectively. The results showed that the compressive strength apparently decreased with the elevated temperature increased. The presence of fly ash was effective for improvement of the relative strength, which was the ratio of residual compressive strength after exposure to elevated temperature and ordinary concrete. The relative compressive strength of fly ash concrete was higher than those of ordinary concrete. Based on the experiments results, the alternating simulation formula to determine the relationship among relative strength, elevated temperature and fly ash replacement is developed by using regression of results, which provides the theoretical basis for the evaluation and repair of HFCC after elevated temperature.

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