Field measurement of slow metamorphic reaction rates at temperatures of 500 degrees to 600 degrees C

High-temperature metamorphic reaction rates were measured using strontium isotopic ratios of garnet and whole rock from a field site near Simplon Pass, Switzerland. For metamorphic conditions of cooling from 612 degrees +/- 17 degrees C to 505 degrees +/- 15 degrees C at pressures up to 9.1 kilobars, the inferred bulk fluid-rock exchange rate is 1.3(-0.4)(+1.1) x 10(-7) grams of solid reacted per gram of solid per year, several orders of magnitude lower than laboratory-based estimates. The inferred reaction rate suggests that mineral chemistry may lag the evolving conditions in Earth's crust during mountain building.     

Deformation twins in hornblende

Hornblende deformation twins with twin planes parallel to ( 101) are produced experimentally in single crystals by compression parallel to the c axis. Twinning occurs at confining pressures from 5 to 15 kilobars and temperatures from 400 degrees to 600 degrees C (strain rate, 10(-5) per second).     

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.     

Biological damage from intranuclear tritium: DNA strand breaks and their repair

Isotopic decay in tritiated thymidine in the DNA of frozen (-196 degrees C) Chinese hamster cells causes breaks in DNA strands to accumulate at a rate of 2.1 breaks per decay. After DNA is thawed the tritium-induced breaks repair rapidly with a half-time of 15 minutes at 37 degrees C. In comparison to breakage by x-rays, the efficiency of DNA strand breakage by tritium is equivalent to 0.48 rad per decay. This dose per decay is close to that predicted by simple dosimetric considerations (0.38 rad per decay) for irradiation by the beta particles from tritium.     

Photosynthetic adaptation to high temperatures: a field study in death valley, california

The photosynthesis of Tidestromia oblongifolia (Amranthaceae) is remarkably well adapted to operate at the very high summer temperatures of the native habitat on the floor of Death Valley. The photosynthetic rate was very high and reached its daily maximum when the light intensity reached its noon maximum at the high leaf temperatures of 460 degrees to 50 degrees C which occurred at this time. At the intensity of noon sunlight the rate decreased markedly when the leaf temperature was experimentally reduced to below 44 degrees C. The optimum rate occurred at 47 degrees C. At this temperature the photosynthetic rate was essentially directly proportional to light intensity up to full sunlight.     

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.     

白条锦蛇耗氧量和耗氧率

测定了5种温度(14 、17、 20、 24和29℃)下,白条锦蛇的耗氧量及耗氧率.结果表明:在这5种温度条件下,白条锦蛇的耗氧量均随体质量的增加而明显增大,而白条锦蛇的耗氧率则刚好相反,随体质量的增加耗氧率反而减小; 另外,白条锦蛇的耗氧量、耗氧率与温度均呈显著的线性回归关系.在14～29℃白条锦蛇的耗氧量、耗氧率均随温度升高而增加,并得出耗氧量x0与温度t的一元线性回归方程:x0=-25.25+3.51t,耗氧率Q0与温度t的一元线性回归方程Q0=-230.25+27.14t.白条锦蛇的耗氧率与温度的变化关系,说明白条锦蛇的新陈代谢率随环境温度改变而改变,在14～29℃白条锦蛇的新陈代谢随环境温度升高而加快.     

Energetics of honeybee swarm thermoregulation

Honeybee swarms regulate their core temperature at a high set point (near 36 degrees C) and the mantle at a low set point (near 15 degrees C). The temperature gradient from core to mantle permits considerable energy economy, and it is abolished only shortly before swarm takeoff.     

Temperature regulation of bacterial activity during the spring bloom in newfoundland coastal waters

While the spring phytoplankton bloom in Newfoundland coastal waters is in progress during April and May, at water temperatures between -1 degrees and +2 degrees C, bacterial growth and respiratory rates remain low. Microbial community respiration is not measurable at -0.2 degrees C. Particulate materials that would be utilized by microorganisms in 2 to 3 days at 20 degrees to 25 degrees C require 11 days at 4 degrees C and 18 days at -0.2 degrees C. Thus, photosynthesis is active but microbial utilization of the products is suppressed. High secondary production in cold water may result from the low rate of microbial decomposition, enabling herbivores to utilize much of the primary production.     

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.     

温度对水曲柳种子萌发过程中物质转化和内源激素含量的影响

以经过层积处理解除休眠的水曲柳(Fraxinus mandshurica Rupr.)种子为材料,在两种不同温度条件下进行萌发试验,探讨温度对种子萌发过程中物质转化和内源激素含量的影响.结果表明:与适宜温度下萌发相比,较高温度(25 ℃)下萌发时,种胚中GA3和ZT含量降低,种胚和胚乳中ABA含量升高,种胚中GA3/ABA、IAA/ABA、ZT/ABA的比值降低.内源激素向利于种子休眠的方向发展,从而使种子中脂肪酶和β-淀粉酶活性受抑制,脂肪和淀粉的分解缓慢,可溶性蛋白和糖的进一步代谢受到不同程度的抑制,导致种子不能正常萌发.     

Activation volume for creep in the upper mantle

The activation volume for creep, V*, of olivine-rich rocks has been determined in pressure-differential creep experiments on dunite at temperatures from 1100 degrees to 1350 degrees C and confining pressures from 5 to 15 kilobars. Values of V* range from 10.6 to 15.4 cubic centimeters per mole with a mean value of 13.4 cubic centimeters per mole, near that expected for oxygen ion self-diffusion. The quantity V* is incorporated into existing flow equations; in combination with observations on naturally deformed mantle xenoliths, estimates are given of the variation with depth of stress, strain rate, and viscosity.     

Triblock copolymer syntheses of mesoporous silica with periodic 50 to 300 angstrom pores

Use of amphiphilic triblock copolymers to direct the organization of polymerizing silica species has resulted in the preparation of well-ordered hexagonal mesoporous silica structures (SBA-15) with uniform pore sizes up to approximately 300 angstroms. The SBA-15 materials are synthesized in acidic media to produce highly ordered, two-dimensional hexagonal (space group p6mm) silica-block copolymer mesophases. Calcination at 500 degrees C gives porous structures with unusually large interlattice d spacings of 74.5 to 320 angstroms between the (100) planes, pore sizes from 46 to 300 angstroms, pore volume fractions up to 0.85, and silica wall thicknesses of 31 to 64 angstroms. SBA-15 can be readily prepared over a wide range of uniform pore sizes and pore wall thicknesses at low temperature (35 degrees to 80 degrees C), using a variety of poly(alkylene oxide) triblock copolymers and by the addition of cosolvent organic molecules. The block copolymer species can be recovered for reuse by solvent extraction with ethanol or removed by heating at 140 degrees C for 3 hours, in both cases, yielding a product that is thermally stable in boiling water.     

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.     

Thermal preference and tolerance of alvinellids

The highest oceanic temperatures are found at hydrothermal vents, where the polychaete Paralvinella sulfincola lives on vent sulfides within steep and dynamic thermal gradients. To determine P. sulfincola thermotolerance and preference, we developed a high-pressure aquarium that mimics in situ thermal gradients and permits P. sulfincola to move within the gradient. These polychaetes were thermotaxic, preferring temperatures of 40 degrees to 50 degrees C. Some individuals remained at 50 degrees C for 7 hours (the duration of the experiment), whereas others endured exposure to 55 degrees C for over 15 minutes, demonstrating that alvinellids prefer high temperatures and are among the most thermotolerant of marine organisms.     

Steelhead migration: potential temperature effects as indicated by gill adenosine triphosphatase activities

Yearling steelhead trout held in fresh water at cold temperatures (6.5 degrees or 10 degrees C) showed an increase in gill microsomal Na(+), K(+)-stimulated adenosine triphosphatase activity during parr-smolt transformation, whereas trout held in warm water (15 degrees or 20 degrees C) did not. Adenosine triphosphatase activity increased and other indications of transformation were observed in fish transferred from warm to cold water, whereas the reverse occurred on transfer from cold to warm water.     

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.     

A Relationship between Photoperiod and Cold-Storage Treatment in the Spruce Budworm

Exposure of diapausing second-instar larvae of Choristoneura fumiferana to continuous light at 21 degrees C, after only 6 weeks' storage at 0 degrees C, induces emergence of larvae that will not emerge in photoperiods of 15 or 18 hours. Following the normal storage period (20 weeks) there is no such effect. Complete dark or 12-hour photoperiods inhibit emergence after storage periods of all lengths.     

Temperature regulation by the inflorescence of philodendron

The inflorescence of Philodendron selloum temporarily maintains a core temperature of 38 degrees to 46 degrees C, despite air temperatures ranging from 4 degrees to 39 degrees C, by means of a variable metabolic rate. The heat is produced primarily by small, sterile male flowers that are capable of consuming oxygen at rates approaching those of flying hummingbirds and sphinx moths.     

Silicon oxynitride stability

Silicon oxynitride occurs as a mineral (sinoite) in meteorites. Equilibrium measurements are reported which provide information on the approximate ratios of pressures of oxygen to nitrogen required for existence of this phase under equilibrium conditions at elevated temperatures. This ratio is approximately 10-(15) at 1400 degrees to 1500 degrees C.