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"Temperature Experiments."
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Cool experiments with heat and cold
Reading about heat and cold is just the tip of the iceberg. This book lets readers create their own icebergs! Hands-on activities make learning about heat and cold both tangible and fun. Simple explanations help readers grasp complex concepts while step-by-step instructions and accompanying photographs ensure they will master each experiment.
Book
Element loss to platinum capsules in high-temperature–pressure experiments
Element partition coefficients play key roles in understanding various geological processes and are typically measured by performing high-temperature–pressure (HTP) experiments. In HTP experiments, samples are usually enclosed in capsules made of noble metals. Previous studies have shown that Fe, Ni, and Cu readily alloy with noble metals, resulting in significant loss of these elements from the experimental samples. The loss of elements could severely undermine phase equilibrium and compromise the validity and accuracy of the obtained partition coefficients. However, it remains unclear if other elements (in addition to Fe, Ni, and Cu) will also be lost from samples during HTP experiments, and how to minimize such losses. We performed a series of experiments at 1 GPa and 1400 °C to investigate which elements will be lost from samples and explore the influence of capsule materials and oxygen fugacity (
) on the loss behavior of elements. The starting material is a synthesized basaltic glass consisting of 8 major elements and 37 trace elements. The sample capsules included platinum (Pt), graphite-lined Pt, and rhenium-lined Pt, and the experimental oxygen fugacity (
) was buffered from
Journal Article
How hot is hot? : science projects with temperature
Provides instructions for doing experiments involving temperature using items found around the house.
Book
Thirty years of coral heat-stress experiments: a review of methods
For over three decades, scientists have conducted heat-stress experiments to predict how coral will respond to ocean warming due to global climate change. However, there are often conflicting results in the literature that are difficult to resolve, which we hypothesize are a result of unintended biases, variation in experimental design, and underreporting of critical methodological information. Here, we reviewed 255 coral heat-stress experiments to (1) document where and when they were conducted and on which species, (2) assess variability in experimental design, and (3) quantify the diversity of response variables measured. First, we found that two-thirds of studies were conducted in only three countries, three coral species were more heavily studied than others, and only 4% of studies focused on earlier life stages. Second, slightly more than half of all heat-stress exposures were less than 8 d in duration, only 17% of experiments fed corals, and experimental conditions varied widely, including the level and rate of temperature increase, light intensity, number of genets used, and the length of acclimation period. In addition, 95%, 55%, and > 35% of studies did not report tank flow conditions, light–dark cycle used, or the date of the experiment, respectively. Finally, we found that 21% of experiments did not measure any bleaching phenotype traits, 77% did not identify the Symbiodiniaceae endosymbiont, and the contribution of the coral host in the physiological response to heat-stress was often not investigated. This review highlights geographic, taxonomic, and heat-stress duration biases in our understanding of coral bleaching, and large variability in the reporting and design of heat-stress experiments that could account for some of the discrepancies in the literature. Development of some best practice recommendations for coral bleaching experiments could improve cross-studies comparisons and increase the efficiency of coral bleaching research at a time when it is needed most.
Journal Article
Rapid surficial oxidation of synthetic Fe-Ti oxides at high temperature: Observations and consequences for magnetic measurements
Synthetic polycrystalline samples of Fe‐Ti oxides (titanomagnetite, Tmtss; ilmenite‐hematitess, Ilmss; pseudobrookitess, Psbss) are very sensitive to changes in the redox conditions at high temperatures, either during synthesis experiments or during thermomagnetic measurements. For instance, exposure to air for a few seconds at the end of a synthesis run at 1300°C of a Tmtss‐Ilmss sample produces surficial oxidation down to a depth of some 100 μm. This oxidation zone is well visible on backscattered electron images of polished sections through the sample pellet. It is characterized by so‐called trellis “oxyexsolution” textures, i.e., fine lamellae of Ilmss within the Tmtss crystals and lamellae of Psbss within the Ilmss crystals. In this oxidation zone the newly grown Ilmss lamellae and the surrounding Tmtss are more Fe rich than the original crystals. The presence of trellis textures in the crystals of both coexisting phases, Tmtss and Ilmss, show that only short‐scaled elemental transport within the crystals was involved and that equilibrium was not attained. Even though the oxidation zone is very narrow, the imprint of the new Tmtsscompositions is well recognizable in temperature‐dependent magnetic susceptibility curves. In temperature‐dependent saturation magnetization (MS‐T) curves, however, the contribution of more Fe‐rich Tmtss from the oxidation zone can be easily overseen. However, surficial oxidation of Tmtss does occur during MS‐T measurements with a variable field translation balance, apparently in relation with insufficient Ar flowing around the sample. Further examples of rapid surficial oxidation of Fe‐Ti oxide samples are also discussed. Key Points The surface of Fe‐Ti oxides oxidizes within seconds in air above 700 degrees C Surface oxidation of Fe‐Ti oxides produces oxyexsolutions Surface oxidation is revealed by T‐dependent magnetic susceptibility curves
Journal Article
Trace-element mobility in pelite-derived supercritical fluid-melt at subduction-zone conditions
The mobility of trace elements in supercritical fluid-melt derived from pelite rich in volatiles has been studied experimentally at pressures from 3.0 to 7.8 GPa and temperatures from 750 to 1090 °С using the diamond trap method. The experiments simulate the conditions of warm and hot subduction, in which pelite either retains the whole inventory of volatiles or releases a fluid in three successive devolatilization steps. The 3.0 GPa and 750 °С runs with pelite rich in volatiles yield a supercritical fluid (SCF) which attains equilibrium with an eclogitic residue bearing phengite and accessory rutile, zircon, and monazite. At ≥5.5 GPa and ≥850 °С, above the second critical endpoint, the SCF transforms into a supercritical fluid-melt (SCFM) which acquires higher concentrations of almost all incompatible trace elements while the mineral assemblage of the equilibrium eclogitic residue remains the same but lacks monazite. The trace-element enrichment of SCFM is most prominent for Ba, Sr, LREE, Th, and U. At the hot subduction conditions, the fluid-melt likewise contains more K, Rb, Zr, and Hf, though LREE contents become lower. The negative Nb anomaly persists in all cases. SCFM has its trace-element composition generally similar to that of hydrous melt derived from oceanic sediments, but contains more REEs and water. Partitioning of LILE, HFSE, and LREE between the SCFM and residue phases mainly depends on the fluid-melt fraction and stability of host phengite, monazite, zircon, and rutile. Thus, sediment-derived SCFM can carry both fluid-mobile and sediment-melt elements to regions of arc- and back-arc magma generation and can translate the negative Nb anomaly inherited from sediment into the magmas. Early devolatilization of pelite increases the stability of monazite and phengite in the residue and provides efficient LREE, K and Rb transport to the mantle depths of ~ 250 km. Effective LREE and Th depletion of UHP metamorphic rocks is possible by SCFM release near peak metamorphic conditions.
Journal Article
Thermodynamic and kinetic controls on phase stability and incorporation of water in larnite (β-Ca2SiO4): implications for calcium silicate inclusions in diamonds
Larnite (β-Ca
2
SiO
4
) has previously been reported as an inclusion in sub-lithospheric diamonds and is generally interpreted as a retrograde reaction product of calcium silicate perovskite. In this study, we review the controls on the stability of the Ca
2
SiO
4
polymorphs and show that phosphorus is likely essential for the preservation of β-Ca
2
SiO
4
. We also report a detailed study of the solubility of water and its incorporation mechanisms in γ-Ca
2
SiO
4
and phosphorus-doped β-Ca
2
SiO
4
using FTIR spectroscopy on high-pressure experiments quenched from 4–9.5 GPa and 1000–1200 °C combined with ab initio calculations. The experimentally determined water solubilities are in the range of 107–178 ppm. Our FTIR spectra and ab initio calculations indicate that for phosphorus-free γ-Ca
2
SiO
4
the incorporation mechanism involves protonated Si and Ca1 vacancies. For phosphorus-bearing β-Ca
2
SiO
4
, our preferred incorporation mechanism involves one Si
4+
ion replaced by one P
5+
ion with a single protonated Ca2 vacancy. The low water solubility observed here for larnite implies that if primary calcium silicate perovskite inclusions trap high water concentrations during diamond growth from a volatile-rich fluid, measurements of the concentration of water in larnite will not provide a useful record of the initial volatile concentration. Instead, water would be hosted in other retrograde reaction products, possibly including exsolved fluids.
Journal Article
Sensing Properties of Fused Silica Single-Mode Optical Fibers Based on PPP-BOTDA in High-Temperature Fields
The strain of fiber-reinforced polymer (FRP) bars at high temperatures is currently difficult to measure. To overcome this difficulty, a method of smart FRP bars embedded with optical fibers was proposed and studied, in which an ordinary single-mode optical fiber was applied as a distributed sensor. In this paper, both the distributed temperature and strain-sensing characteristics of optical fiber were studied based on pulse pre-pump Brillouin optical time-domain analysis (PPP-BOTDA) under high temperature. The temperature and strain coefficients were investigated under a thermomechanical coupling environment with consideration of large strain levels. The experimental results show that the temperature and strain coefficients decreased as the temperature increased, because the properties of silica and coating materials changed with temperature. Then, the formulas for determining the temperature and strain coefficients at high temperatures were introduced and discussed. The excellent sensing performance of the optical fiber indicated that smart FRP bars have the potential for use at high temperatures.
Journal Article
Composition of supercritical fluid in carbonate- and chlorine-bearing pelite at conditions of subduction zones
The composition of fluid from carbonate- and chlorine-bearing pelite has been studied at 5.5 GPa, 850–1030 °C and at 7.8 GPa, 940–1090 °C using the diamond trap method. The run products include a residue composed of an eclogitic assemblage (garnet, coesite, clinopyroxene, and kyanite ± phengite and accessory pyrite/pyrrhotite, rutile, and zircon) and fluid solutes captured in the trap. The new data show that the pelite-derived supercritical fluid, with nearly equal amounts of solutes and H2O + CO2 [at the weight ratio H2O/(H2O + CO2) from 0.8 to 0.9], is stable at the applied P–T conditions. At higher temperatures, the amount of solutes in the supercritical fluid increases only slightly, apparently, due to the presence CO2 and 0.4–0.5 wt% Cl in the fluid. The reconstructed supercritical fluid composition includes components decreasing in the series SiO2 > Al2O3 > K2O > Na2O ≈ CaO ≈ MgO ≈ FeO. At 7.8 GPa, phengite becomes unstable, and K2O in the supercritical fluid increases from 3 to 8 wt% (on hydrous basis) while Al2O3 decreases from 8 to 5–6 wt%. Among the elements that fractionated into the fluid, B, Sr, Rb and P, as well as K at 7.8 GPa and 1090 °C, are the least compatible. The fluid-residue Sr partition coefficient varies from 4 to 10 and is notably lower at higher temperatures. Thus, supercritical fluids can form in carbonate- and chlorine-bearing sediments under subduction back arc-conditions, in cases of fluid-fluxing of the slab. Such supercritical fluids penetrating into the mantle together with H2O and CO2 can transport large amounts of major elements, B, Sr, Rb and P. The formation of potassium-rich silicic supercritical fluids is possible during subduction of pelite to ~ 250 km depths. They can be important agents in metasomatism of lithospheric mantle, with its composition reconstructed from data on micro-inclusions from fibrous diamond.
Journal Article
Gold solubility in silicate melts and fluids: Advances from high-pressure and high-temperature experiments
The solubility of Au in silicate melts and fluids governs the enrichment and migration of Au during the formation of magmatic-hydrothermal Au deposits. Large Au deposits require vast amounts of Au to migrate from the upper mantle-lower crust to the shallow crust, and high Au solubility in magma and hydrothermal fluid facilitates the formation of Au-rich magma and fluid in the crust and mantle source and efficient transport This paper reviews recent high-pressure and high-temperature experimental studies on Au species in magmas and hydrothermal fluids, the partitioning behavior of Au between silicate melts and fluids, and the effects of temperature, pressure, oxygen fugacity, sulfur fugacity, silicate melt composition, and volatiles (H
2
O, CO
2
, chlorine, and sulfur) on the solubility of Au in magma. We show that the solubility of Au in magma is largely controlled by the volatiles in the magma: the higher the content of reduced sulfur (S
2−
and HS
−
) in the magma, the higher the solubility of Au. Under high-temperature, high-pressure, H
2
O-rich, and intermediate oxygen fugacity conditions, magma can dissolve more reduced sulfur species, thus enhancing the ability of the magma to transport Au. If the ore-forming elements of the Au deposits in the North China Craton originate from mantle-derived magmas and fluids, we can conclude, in terms of massive Au migration, that these deep Au-rich magmas might have been generated under H
2
O-rich and moderately oxidized conditions (S
2−
coexists with S
6+
). The big mantle wedge beneath East Asia was metasomatized by melts and fluids from the dehydration of the Early Cretaceous paleo-Pacific stagnant slab, which not only caused thinning of the North China Craton, but also created physicochemical conditions favorable for massive Au migration.
Journal Article