Regulation of body temperature in the blue-tongued lizard

Lizards (Tiliqua scincoides) regulated their internal body temperature by moving back and forth between 15 degrees and 45 degrees C environments to maintain colonic and brain temperatures between 30 degrees and 37 degrees C. A pair of thermodes were implanted across the preoptic region of the brain stem, and a reentrant tube for a thermocouple was implanted in the brain stem. Heating the brain stem to 41 degrees C activated the exit response from the hot environment at a colonic temperature 1 degrees to 2 degrees C lower than normal, whereas cooling the brain stem to 25 degrees C delayed the exit from the hot environment until the colonic temperature was 1 degrees to 2 degrees C higher than normal. The behavioral thermoregulatory responses of this ectotherm appear to be activated by a combination of hypothalamic and other body temperatures.     

Ultraviolet damage to bacteria and bacteriophage at low temperatures

The survival of Escherichia coli B/r WP2 (tryptophan-requiring) from ultraviolet irradiation when suspended in 0.067M phosphate buffer (pH 7) has been studied over the temperature range 22 degrees to -269 degrees C. In unfrozen suspensions there was no appreciable change in sensitivity between 22 degrees and -10 degrees C. The sensitivity in the presence of ice progressively increased by a factor of 7 when the temperature was lowered to -79 degrees C. Between -79 degrees and -196 degrees C the sensitivity decreased to less than four times the sensitivity at 22 degrees C and was not appreciably different at -269 degrees C. Evidence from experiments with bacteriophage T1 and E. coli WP2 HCR(-) (a strain unable to excise thymine dimers) indicates that a new, qualitatively different lesion, less amenable to repair, may replace the thymine dimer in E. coli irradiated at -79 degrees C.     

Kinetics of the fe2+-mg, order-disorder reaction in anthophyllites: quantitative cooling rates

The kinetics of the Fe(2+)-Mg, order-disorder phenomenon in a highly ordered natural anthophyllite have been determined over the temperature range from 400 degrees to 720 degrees C at a pressure of 2 kilobars. At temperatures of 600 degrees C and above, equilibrium is attained by disordering as well as ordering reactions. The intracrystalline exchange is defined by a standard Gibbs free energy of 4247 +/- 54 calories per formula unit. Rate studies at 550 degrees and 500 degrees C show that equilibrium is attained by ordering but not by disordering within the same time scale and that the exchange reaction is characterized by an activation energy of approximately 55 kilocalories per formula unit. An equilibration temperature for the natural anthophyllite of 270 degrees C is determined from the termination of the ordering process owing to excessively slow reaction kinetics after approximately 10(7) years. From the rate constants of the exchange process, for different crystallization temperatures, the apparent equilibration temperature of 270 degrees C defines a maximum linear cooling rate for the rock of 1 x 10(4) degrees C per year.     

Bacterial Sulfate Reduction Above 100{degrees}C in Deep-Sea Hydrothermal Vent Sediments

The currently known upper temperature limit for growth of organisms, shared by a number of archaebacteria, is 110 degrees C. However, among the sulfate-reducing bacteria, growth temperatures of greater than 100 degrees C have not been found. A search for high-temperature activity of sulfate-reducing bacteria was done in hot deep-sea sediments at the hydrothermal vents of the Guaymas Basin tectonic spreading center in the Gulf of California. Radiotracer studies revealed that sulfate reduction can occur at temperatures up to 110 degrees C, with an optimum rate at 103 degrees to 106 degrees C. This observation expands the upper temperature limit of this process in deep-ocean sediments by 20 degrees C and indicates the existence of an unknown group of hyperthermophilic bacteria with a potential importance for the biogeochemistry of sulfur above 100 degrees C.     

Flight of Winter Moths Near 0{degrees}C

Some noctuid winter moths fly at near 0 degrees C by maintaining an elevated(30 degrees to 35 degrees C) thoracic muscle temperature. Geometrid winter moths sustain themselves in free flight at subzero muscle temperatures. However, the temperature characteristics of citrate synthase and pyruvate kinase from both of these different kinds of moths and from a sphinx moth that flies with a muscles temperature of 40 degrees C are nearly identical. Furthermore, mass-specific rates of energy expenditure of both kinds of winter moths are also similar at given thoracic temperature (near 0 degrees C). The geometrids that are able to fly with a thoracic temperature near 0 degrees C do so largely because of unusually low wing-loading, which permits a low energetic cost of flight.     

Starch accumulation associated with growth reduction at low temperatures in a tropical plant

Growth of Digitaria decumbens is severely reduced by night temperatures of 10 degrees C or below. Ultra-structure of leaves and chemical analyses show a high starch content in chloroplasts of plants illuminated and kept at a temperature of 30 degrees C. This starch disappears after a period in the dark at 30 degrees C, but it remains if the temperature during the dark period is 10 degrees C. The inhibition or slowing of starch translocation out of chloroplasts appears to account for reduced photo-synthesis and growth at low night temperatures.     

New phases of c60 synthesized at high pressure

The fullerene C(60) can be converted into two different structures by high pressure and temperature. They are metastable and revert to pristine C(60) on reheating to 300 degrees C at ambient pressure. For synthesis temperatures between 300 degrees and 400 degrees C and pressures of 5 gigapascals, a nominal face-centered-cubic structure is produced with a lattice parameter a(o) = 13.6 angstroms. When treated at 500 degrees to 800 degrees C at the same pressure, C(60) transforms into a rhombohedral structure with hexagonal lattice parameters of a(o) = 9.22 angstroms and c(o) = 24.6 angstroms. The intermolecular distance is small enough that a chemical bond can form, in accord with the reduced solubility of the pressure-induced phases. Infrared, Raman, and nuclear magnetic resonance studies show a drastic reduction of icosahedral symmetry, as might occur if the C(60) molecules are linked.     

Triops (Entomostraca) eggs killed only by boiling

Temporary rainpools near Khartoum, Sudan, are inhabited by the notostracan crustacean Triops which completes its life cycle within 4 weeks. The annual rains fall in late summer, and throughout the winter and early summer the eggs of Triops remain in the dried mud or dust where they may be exposed to temperatures up to 80 degrees C. Laboratory experiments show that they can withstand temperatures up to within 1 degrees C of boiling, but are killed in partial vacuum by 70 degrees C, at atmospheric pressure by 100 degrees C, or under pressure by 105 degrees C. Exposure to high temperature seems to be necessary to break the egg diapause.     

Heat production and temperature regulation in eastern skunk cabbage

The spadix of Symplocarpus foetidus L. maintains an internal temperature 15 degrees to 35 degrees C above ambient air temperatures of -15 degrees to +15 degrees C. For at least 14 days it consumes oxygen at a rate comparable to that of homeothermic animals of equivalent size. Temperature regulation is accomplished by variations in respiratory rate.     

Bulk isolation in nonaqueous media of nuclei from lyophilized cells

Intact lyophilized nuclei are obtainable from a variety of tissues, either in situ or in culture, by freezing at -156 degrees C, drying at -25 degrees C, and mechanical disassociation in glycerol at 2 degrees C. Centrifugal separation of nuclei is accomplished in an 85 : 15 by volume mixture of glycerol and 3-chloro-1,2 propanediol at 2 degrees C. The method gives homogeneous nuclear preparations in high yield with preservation of labile and water-soluble constituents.     

Interferon binding: the first step in establishment of antiviral activity

Chick cells incubated at 1 degrees C with interferon fail to develop antiviral activity, but this activity appears subsequent to a 7-hour incubation at 37 degrees C after removal of interferon by repeated washings. Treatment with actinomycin D blocks the development of the latter activity. Cells incubated with interferon at 1 degrees C for up to 1 hour and then washed and incubated for 2 hours at 37 degrees C develop a degree of antiviral activity proportional to the concentration of interferon at initial incubation; at any concentration, the antiviral activity increased with the duration of initial incubation at 1 degrees C, but a maximal response was reached at 10 or 20 minutes. Treatment with trypsin after incubation with interferon at 1 degrees C inhibited development of antiviral activity. Interferon is rapidly bound to a superficial cell site, and this binding is necessary for development of antiviral activity in chick cells.     

Thermophilic ostracod: aquatic metazoan with the highest known temperature tolerance

The upper lethal temperature for an ostracod of the genus Potamocypris collected from a thermal stream ranged from 49 degrees C for incubation of more than 5 hours to 55.75 degrees C for 1-minute incubations. Field collections were held at 35 degrees C for less than 24 hours before experimental incubations. Calculated temperatues for 50 percent mortality for 60, 40, 20, 10, 5, and 1 minute of exposure were 50.44 degrees , 50.96 degrees , 51.43 degrees , 52.03 degrees , 52.77 degrees , and 55.12 degrees C, respectively.     

Temperature Regulation in the Bumblebee Bombus vagans: A Field Study

Bombus vagans forages for nectar at 5 degrees C in shade and at 31 degrees C in sunshine. The production of heat while the bumblebee is on flowers, at ambient temperatures below 24 degrees C, helps to maintain a thoracic temperature that is near the minimum for flight between flowers. However, at ambient temperatures above 24 degrees C the thoracic temperature is no longer regulated at 32 degrees to 33 degrees C and rises.     

Strength of diamond

The yield strength of diamond is measured under a pressure of 10 gigapascals at temperatures up to 1550 degrees C by the analysis of x-ray peak shapes on diamond diffraction lines in a powdered sample as a function of pressure and temperature. At room temperature, the diamond crystals exhibit elastic behavior with increasing pressure. Significant ductile deformation is observed only at temperatures above 1000 degrees C at this pressure. The differential yield strength of diamond decreases with temperature from 16 gigapascals at 1100 degrees C to 4 gigapascals at 1550 degrees C. Transmission electron microscopy observations on the recovered sample indicate that the dominant deformation mechanism under high pressure and temperature is crystal plasticity.     

Hemoglobin Kinetics of the Galapagos Rift Vent Tube Worm Riftia pachyptila Jones (Pogonophora; Vestimentifera)

Kinetics of the reactions of Riftia pachyptila hemoglobin with oxygen were followed spectrophotometrically by stopped-flow and laser flash photolysis techniques. The rate of oxygen dissociation increases eightfold over the range of 5 degrees to 20 degrees C (k = 2.2 sec(-1)at 10 degrees C). Oxygen recombination after flash photolysis was biphasic. The rates of both slow and fast phases of the reaction were independent of temperature from 0 degrees to 20 degrees C(k'fast = 7 x 10(6); k'slow = 1 x 16(6) liter mole (-1) sec(-1)). As the oxygen affinity is relatively temperature independent, analysis in terms of the two-state model of cooperativity requires that the conformational equilibrium constant L decrease by about 50-fold between 3 degrees and 15 degrees C.     

Cooperative critical thermal transition of potassium accumulation in smooth muscle

The steady-state levels of potassium and sodium of taenia coli of guinea are critically affected by varying temperature in the narrow range 12 degrees to degrees C. For the accumulation of both cations the critical temperature, T(c), is 13.8 degrees C the presence of millimolar external potassium. The value of T(c), decreases 10.0 degrees C when the external potassium is raised to 10 millimolar. Since, at a fixed Temperature, the potassium accumulation follows a cooperative mechanism, the results are compared with the quantitative predictions of this approach. The itical thermal transition behavior can be described in terms of the cooperative cumulation process.     

High-thermoelectric performance of nanostructured bismuth antimony telluride bulk alloys

The dimensionless thermoelectric figure of merit (ZT) in bismuth antimony telluride (BiSbTe) bulk alloys has remained around 1 for more than 50 years. We show that a peak ZT of 1.4 at 100 degrees C can be achieved in a p-type nanocrystalline BiSbTe bulk alloy. These nanocrystalline bulk materials were made by hot pressing nanopowders that were ball-milled from crystalline ingots under inert conditions. Electrical transport measurements, coupled with microstructure studies and modeling, show that the ZT improvement is the result of low thermal conductivity caused by the increased phonon scattering by grain boundaries and defects. More importantly, ZT is about 1.2 at room temperature and 0.8 at 250 degrees C, which makes these materials useful for cooling and power generation. Cooling devices that use these materials have produced high-temperature differences of 86 degrees , 106 degrees , and 119 degrees C with hot-side temperatures set at 50 degrees, 100 degrees, and 150 degrees C, respectively. This discovery sets the stage for use of a new nanocomposite approach in developing high-performance low-cost bulk thermoelectric materials.     

温度和叶表化学物质对松杨栅锈菌夏孢子萌发的影响

松杨栅锈菌夏孢子萌发适宜温度范围为10～24℃,最适温度20℃左右。供试的2菌株对温度有不同的依赖性。TH菌株温度适应性范围较宽,GL菌株较窄。在最适温度范围内,供试的2个菌株呈现相同的萌发动力学模式,萌发最大速率出现在4～12h,温度越高,最大萌发速率出现时间越晚,并随时间的延长,萌发速率逐渐减小。在5、30℃,萌发速率有2～3个峰值,第1峰值最大,第2、第3峰值逐渐减小或消失。26℃下峰值呈现过渡型状态,有1个较小的次高峰。供试的2菌株,TH的萌发速率较GL稍高并在出现时间上略前。最适萌发条件下,石油醚、乙醚、乙酸乙酯、正丁醇、水的卜氏杨和毛白杨提取物对松杨栅锈菌夏孢子萌发有不同的影响。毛白杨所有提取物在接种12h内,均抑制夏孢子的萌发,而卜氏杨乙醚提取物则促进夏孢子萌发,其余则抑制夏孢子萌发。所有水提取物在接种12h均表现为抑制作用。接种12～24h,2种杨树叶片正丁醇萃取物对夏孢子萌发速率均有一定程度的促进作用。     

The silica-alumina system: stable and metastable equilibria at 1.0 atmosphere

Diffusion couples, consisting of sapphire and fused silica, which were annealed in the temperature range from 1678 degrees to 2003 degrees C and analyzed by electron beam microprobe, have provided data on the stable phase equilibrium of the silica-alumina system. Under stable equilibrium conditions, the intermediate compound of this system, mullite (3Al(2)O(3) . 2SiO(2)), melts incongruently at 1828 degrees +/- 10 degrees C and its solid solution field extends from 70.5 to 74.0 percent (by weight) alumina. The stable phase diagram is a composite of the two binary eutectic diagrams: silica-mullite in the absence of alumina and silica-alumina in the absence of mullite. Under metastable conditions, mullite melts congruently at approximately 1890 degrees +/- 10 degrees C and its solid solution field extends to approximately 83.2 percent (by weight) alumina.     

Feeding and core temperature in albino rats: changes induced by preoptic heating and cooling

At an ambient temperature of 25 degrees C, selective cooling of the area preoptica medialis to 24 degrees +/- 1 degrees C produced a significant decrease in food intake together with hyperthermia. Heating the same area to 43 degrees +/- 1 degrees C resulted in the opposite effects. At an ambient temperature of 35 degrees C, heating the area preoptica medialis to 43 degrees C resulted in a decrease in food intake despite concomitant hypothermia.