Effect Of Cooling Temperature Research Articles

The Effect of Cooling Temperature on Microstructure and Mechanical Properties of Al 6061-T6 Aluminum Alloy during Submerged Friction Stir Welding

Submerged friction stir welding (SFSW) is a new modification of friction stir welding. In this paper, 6 mm thick 6061Al-T6 alloy plates were welded using the friction stir technique under normal air and submerged water conditions at 108 mm/min welding speeds and a rotational rate of 900 rpm. The cooling water temperature in SFSW varied at 0 °C, 35 °C, and 80 °C to clarify the effect of water temperature. The characteristic hourglass-shaped stir zone was observed in the macrostructure of all the samples. All the samples exhibited defect-free joints. The results revealed that the finer grain size of 2.43 μm was at 0 °C. The macrostructure of SFSW joints separated into the shoulder-driven zone and pin-driven zone due to the low-temperature difference between the environment and water media and the high heat absorption capacity of the water, which caused a more substantial cooling rate during water-submerged welded joints. The microhardness distribution of all the joints showed typical “W” shape characteristics. The microhardness for all submerged samples was higher than in normal air conditions due to the higher thermal cycling effect in submerged conditions. Improved dynamic recrystallization in the joint welded at 80 °C resulted in the highest tensile strength (~249 MPa) and microhardness (~95 HV).

The Role of Temperature in Moral Decision-Making: Limited Reproducibility.

Temperature is one of the major environmental factors that people are exposed to on a daily basis, often in conditions that do not afford control. It is known that heat and cold can influence a person’s productivity and performance in simple tasks. With respect to social cognition, it has also been suggested that temperature impacts on relatively high-level forms of decision-making. For instance, previous research demonstrated that cold temperature promotes utilitarian judgment in a moral dilemma task. This effect could be due to psychological processing, when a cool temperature primes a set of internal representations (associated with “coldness”). Alternatively, the promotion of utilitarian judgment in cold conditions could be due to physiological interference from temperature, impeding on social cognition. Refuting both explanations of psychological or physiological processing, however, it has been suggested that there may be problems of reproducibility in the literature on temperature modulating complex or abstract information processing. To examine the role of temperature in moral decision-making, we conducted a series of experiments using ambient and haptic temperature with careful manipulation checks and modified task methodology. Experiment 1 manipulated room temperature with cool (21°C), control (24°C) and hot (27°C) conditions and found only a cool temperature effect, promoting utilitarian judgment as in the previous study. Experiment 2 manipulated the intensity of haptic temperature but failed to obtain the cool temperature effect. Experiments 3 and 4 examined the generalizability of the cool ambient temperature effect with another moral judgment task and with manipulation of exposure duration. However, again there were no cool temperature effects, suggesting a lack of reproducibility. Despite successful manipulations of temperature in all four experiments, as measured in body temperature and the participants’ self-reported perception, we found no systematic influence of temperature on moral decision-making. A Bayesian meta-analysis of the four experiments showed that the overall data tended to provide strong support in favor of the null hypothesis. We propose that, at least in the range of temperatures from 21 to 27°C, the cool temperature effect in moral decision-making is not a robust phenomenon.

Temperature-mortality relationship in dairy cattle in France based on an iso-hygro-thermal partition of the territory

The issue of global warming and more specifically its health impact on populations is increasingly concerning. The aim of our study was to evaluate the impact of temperature on dairy cattle mortality in France during the warm season (April–August). We therefore devised and implemented a spatial partitioning method to divide France into areas in which weather conditions were homogeneous, combining a multiple factor analysis with a clustering method using both weather and spatial data. We then used time-series regressions (2001–2008) to model the relationship between temperature humidity index (an index representing the temperature corrected by the relative humidity) and dairy cattle mortality within these areas. We found a significant effect of heat on dairy cattle mortality, but also an effect of cooler temperatures (to a lesser extent in some areas), which leads to a U-shaped relationship in the studied areas. Our partitioning approach based on weather criteria, associated with classic clustering methods, may contribute to better estimating temperature effects, a critical issue for animal health and welfare. Beyond the interest of its use in animal health, this approach can also be of interest in several situations in the frame of human health.

Cool temperature effects on photosynthetic parameters of two biomass fuel feedstocks in a low light intensity environment

The ability to attain the feedstock production goal in the USA for biofuel production is limited by available arable land, cool temperatures, and periods of low light intensity. This study investigates the effects of warm and cool temperatures growth conditions in a low light regime on the photosynthesis and growth of switchgrass (Panicum virgatum cv. Alamo) and giant miscanthus (Miscanthus giganteus). Alamo switchgrass did not acclimate to low light conditions and had a 47% lower growth and significantly lower mean light saturated photosynthetic rate (Asat = 10.3 μmol m−2s−1) at 14/12°C day/night, compared with 28/25°C (Asat = 18.8 μmol m−2s−1). In contrast, photosynthesis of giant miscanthus acclimated to low light conditions, but there was no significant decrease in quantum requirement or light saturated photosynthetic rates in cool growing conditions (Asat = 8.2 μmol m−2s−1 and 7.0 μmol m−2s−1 for warm and cool conditions, respectively). In summary, giant miscanthus growth and photosynthesis is relatively more tolerant of cool temperature than switchgrass, but is severely limited by low radiation. In contrast, Alamo switchgrass growth and photosynthesis is very sensitive to cool conditions, but is able to maintain higher growth than miscanthus at low radiation conditions.

Effects of Cooling Temperature and Duration on Flowering of the Nobile Dendrobium Orchid

The effects of cooling temperature [constant (10, 13, 15, or 18 °C, or 15, 18, or 21 °C)] and duration (2, 3, 4, 5, or 6 weeks, or 3, 4, 5, 6, or 7 weeks) at two separate locations (College Station and Weslaco, TX) on growth and flowering of Dendrobium Sea Mary ‘Snow King’, a Dendrobium nobile Lindl. hybrid, were investigated and the cooling requirement for flowering was quantified. Interactions between temperature and cooling duration were significant on time required to reach anthesis from either the beginning or completion of cooling, average flower number per flowering node, and percentage of nodes with aborted buds. Increasing cooling duration from 2 to 6 or 3 to 7 weeks resulted in less time to reach anthesis after the completion of cooling. However, the increased cooling durations extended the time needed for producing a flowering crop. Plants cooled at a relatively higher temperature among 10, 13, and 15 °C required less time to reach anthesis after the completion of cooling. Plants had more flowering nodes and total flowers when cooled at 10, 13, or 15 °C than at 18 °C in College Station or at 15 or 18 °C than at 21 °C in Weslaco. The results suggest that 3 weeks at 13 °C has saturated the cooling requirement, and 3 weeks at 13 or 15 °C is a recommended cooling treatment that saves production cost without retarding flower development.

Photoperiod, Irradiance, and/or Cool Temperature Effects on Lobivia × Chamaecereus Hybrid `Rose Quartz' Flowering

Photoperiod, irradiance, and/or a cool temperature effects on Chamaelobivia hybrid `Rose Quartz' flowering was studied. Two- to 3-year-old plants were grown for 4 months under natural daylight (DL; August–November) in a greenhouse maintained at 26 ± 2 °C. Plants were then placed in either of two greenhouses: a cool temperature house (5 ± 2 °C; natural daylight), or a lighting treatment house (22 °C day/18 ± 1 °C night temperature, respectively). The lighting treatment house had eight light environments: 1) short day (SD; 8 h; 0800–1600 HR); 2) SD+25–35 μmol·m-2·s-1; 3) SD+45-50 μmol·m-2·s-1; 4) SD+85-95 μmol·m-2·s-1; 5) DL plus night interruption lighting (NI; 2200–0200 HR; 2 μmol·m-2·s-1 from incandescent lamps); 6) DL+25-35 μmol·m-2·s-1 (lighted from 0800–0200 HR); 7) DL+45-50 μmol·m-2·s-1; and 8) DL+85-95 μmol·m-2·s-1. Supplemental lighting was provided using high-pressure sodium lamps. Plants were placed in the cool temperature environment for 0, 4, 8, or 12 weeks before being placed under lighting treatments. All plants received a 6-week lighting treatment and were then placed in the finishing greenhouse (22 ± 2 °C). Data were collected on the date when each flower opened (five only), the flower number per plant, and flower longevity (five only). Vernalization interacted with photoperiod to affect flowering. Unvernalized plants exhibited an obligate long-day requirement for flowering. Vernalized plants exhibited a facultative long-day requirement for flowering. The impact of vernalization, photoperiod, and irradiance on flower number, time to flower, and longevity will also be discussed.

Cool Temperature-Induced Chlorosis in Rice Plants (II. Effects of Cool Temperature on the Expression of Plastid-Encoded Genes during Shoot Growth in Darkness).

It has been proposed that cool temperature-induced chlorosis (CTIC) in Indica cultivars of rice (Oryza sativa L.) is caused by cell growth and plastid development being impeded at cool temperatures. Since it is well known that the overall rate of transcription of plastid-encoded genes changes dramatically during the early phases of plastid development, in this study we focused on the patterns of expression of these genes. Northern blot analysis revealed that the level of 16S rRNA is decreased in a CTIC-sensitive rice cultivar grown at a cool temperature. The expression of the gene for the [beta] subunit of plasmid RNA polymerase (rpoB) was shown to be somewhat disturbed, particularly in terms of its resuppression under cool conditions. The level of transcripts or proteins of plastid-encoded photosynthetic genes was also decreased in a CTIC-sensitive cultivar at a cool temperature. These results suggest that the temperature-dependent inhibition of the onset of gene expression encoding the transcription/translation apparatus may be primarily involved in the mechanism causing CTIC.

Effects of Cooling Temperature on the Separation of Phosphoamino Acids

Effects of Cooling Temperature on the Separation of Phosphoamino Acids

Cultured Ovules as Models for Cotton Fiber Development under Low Temperatures

Cotton fibers (Gossypium hirsutum L.) developing in vitro responded to cyclic temperature change similarly to those of field-grown plants under diumal temperature fluctuations. Absolute temperatures and rates of temperature change were similar under both conditions. In vitro fibers exhibited a "growth ring" for each time the temperature cycled to 22 or 15 degrees C. Rings were rarely detected when the low point was 28 degrees C. The rings seemed to correspond to alternating regions of high and low cellulose accumulation. Fibers developed in vitro under 34 degrees C/22 degrees C cycling developed similarly to constant 34 degrees C controls, but 34 degrees C/22 degrees C and 34 degrees C/15 degrees C cycling caused delayed onset and prolonged periods of elongation and secondary wall thickening. Control fiber length and weight were finally achieved under 34 degrees C/22 degrees C cycling, but both parameters were reduced at the end of the experiment under 34 degrees C/15 degrees C cycling. Fibers developed under all conditions had equal bundle tensile strength. These results demonstrate that: (a) cool temperature effects on fiber development are at least partly fiber/ovule-specific events; they do not depend on whole-plant physiology; and (b) cultured ovules are valid models for research on the regulation of the field cool temperature response.

Planting Depth and Tillage Interactions on Corn Emergence

AbstractSurface crop residues lower soil temperatures delaying emergence of corn (Zea mays L.) under no‐till tillage systems in the northern Corn Belt. This study evaluates the use of planting depth as a management tool to overcome the disadvantages of cool temperature under residue covered soils. Growth chamber experiments evaluated the effects of planting depths, ranges of soil temperatures, and soil matric potentials on corn emergence. The seeding medium was aggregates of Webster clay loam (fine‐loamy, mixed, mesic Typic Haplaquolls). Deep planting (75 mm) delayed emergence from 2.8 to 18 d as the soil temperatures decreased from ranges of 15 to 25 °C and 5 to 15 ° C. Seed zone growing degree days (GDD) needed to achieve 75% emergence increased with an increase in planting depth and a decrease in soil matric potential. Relationships of corn emergence vs. seed zone GDD needed to achieve 75% corn emergence at various planting depths were tested in the field for three planting depths, three tillage and three surface residue conditions during 1984 and 1985. Predicted time to 75% corn emergence was within 2 d of the field‐measured values for three planting depths, and seven tillage and surface residue conditions, over two seasons. Simulation studies were conducted to predict the effects of tillage, planting depth, and planting date on the probability of obtaining 75% corn emergence within 14 d of planting. Input data for simulation studies included 10 to 20 yr of daily maximum and minimum air temperatures from Morris, MN and Lexington, KY. Tillage treatments included moldboard plow, no surface residue, and no‐till surface residues. Reducing the planting depth from 50 to 25 mm advanced the planting date from 2 d to several weeks, depending on the weather, soil matric potential, and tillage‐surface residue conditions. When soil water is nonlimiting, the effect of cooler temperatures on corn emergence under a no‐till tillage system (with surface residues) can be compensated for by reducing the planting depth by 25 mm or less from that of average planting depth under conventional tillage systems.