Conventional Thermometry Research Articles

A novel high-sensitive upconversion thermometry strategy: Utilizing synergistic effect of dual-wavelength lasers excitation to manipulate electron thermal distribution

Conventional upconversion thermometry strategy, based on the thermally coupled levels (TCL) of lanthanide ions, confronts a dilemma in simultaneously achieving high absolute/relative temperature (T) sensitivities (Sa and Sr) and good signal discriminability. Herein, a novel thermometry strategy by utilizing the synergistic effect of dual-wavelength lasers to manipulate electron thermal distribution is proposed to go beyond the limitation of the TCL-based strategy. In the case of NaGdF4: 20%Yb3+, 2%Er3+ nanoparticles upon 980 & 1530 nm dual-excitation, it is found that more efficient utilization of excited photons results in a higher electron concentration in ladder-like energy levels of Er3+, owing to the diverse pumping routes, which increases transition rate of the T-dependent phonon-assisted cross-relaxation process, and in turn establishes a thermally-sensitive electronic connection between Er3+: 2H11/2,4S3/2 and Er3+: 4F9/2. Remarkably, not only a highest record value of Sa (0.0365 K−1) for the Er3+ doped host materials in the physiological temperature range (303–343 K) is achieved, but also a high Sr (1.29% K-1) and an excellent signal discriminability (Δλ = 112 nm) are obtained. Combining a much intensified upconversion (UC) signal and a good size/shape homogeneity in nanometer scale, the investigated NaGdF4: 20%Yb3+, 2%Er3+ upon dual-wavelength excitation is potentially applicable in the intracellular thermal sensing and imaging. This work exploits an effective way to develop high-performance T-sensors, and the proposed thermometry strategy can be extended to surges of the other lanthanide ions doped systems pumped by multiple-wavelength lasers.

Non-invasive Measurements of Oilseed Temperature in Soil and Soil Thermal Diffusivity Using Time-Domain NMR Relaxometry

Global warming is threatening food production in tropical areas, because the increase of soil temperature may limit seed germination and plant growth. Soil temperature and thermal diffusivity (λ) have been measured using the conventional thermometry. In this study, we are demonstrating that time-domain nuclear magnetic resonance (TD-NMR) relaxometry can be a non-invasive method to determine oilseed temperature in soils and soil thermal diffusivity (λ). The correlation between oilseed transverse relaxation times (T2) and seed temperature has been used to measure the temperatures of intact oilseed in soil samples. To calculate soil thermal diffusivity, spherical soil samples with 7 cm in diameter containing a macadamia nut in the center were heated to 70 °C and then placed in an air bath at room temperature. λ values were calculated using the time constant of oilseed temperature decay, measured by TD-NMR and sample dimensions. The λ values of dry entisol, yellow oxisol, and red oxisol soils were 1.89 × 10−7, 1.52 × 10−7, and 1.03 × 10−7 m2 s−1, respectively. These values were within the same order of magnitude range observed for the values measured by both thermocouple and Dickerson methods. The λ values of dry and moist typic hapludox were 1.16 × 10−7 and 2.29 × 10−7 m2 s−1, respectively. Therefore, TD-NMR is shown to be a feasible method to measure seed temperature in soils and soil thermal diffusivity, and is a potential non-invasive tool to investigate the effect of temperature on seed germination and seedling.

Miniature ammonia loop heat pipe for terrestrial applications: Experiments and modeling

Thermal management is always an exigent topic in various applications like electronic equipment cooling, aerospace, and avionics, defence electronics, etc. Loop Heat Pipes (LHPs) are highly efficient, robust, two-phase, passive heat-transfer devices, increasingly becoming popular for thermal management of terrestrial and avionics applications. Miniaturization of the device and its ability to perform well in different orientations with respect to the gravitational vector are essential for its employment in terrestrial applications. In the present study, complete thermal characterization of the developed ammonia miniature loop heat pipe (mLHP) in different orientations, keeping into view possible terrestrial applications, has been carried out utilizing infrared thermography coupled with conventional thermometry. The maximum capacity obtained is about 225 W (for maximum evaporator temperature of 70 °C) and the thermal resistance was better than 0.5 K/W in all experimental trials irrespective of the orientations. The effect of orientation on the operation of mLHP is insignificant because of its small dimensions and the device can be safely considered to be orientation-free. From the results of the study, mLHP can regard as a quite promising thermal management technology for terrestrial applications. A mathematical model is developed to predict the steady-state evaporator temperature of the mLHP for a given heat load, sink temperature and surrounding temperature. The model has been validated with the experimental results and a good match is obtained.

Gneiss domes of the Danba Metamorphic Complex, Songpan Ganze, eastern Tibet

In this paper we address the formation and exhumation of the Danba Metamorphic Complex (DMC) that represents the deepest structural level of the Songpan Ganze terrane situated along the eastern margin of the Tibetan plateau. The DMC comprises a variety of gneiss domes and offers a unique opportunity to decipher their development during orogenic evolution. For that purpose, PTtD paths of metamorphic rocks sampled at different structural levels have been reconstructed. The DMC is composed of Triassic metaturbidites of the Xikang group, Paleozoic metasedimentary cover and basement of the Yangtze craton. The DMC is structurally marked by transposition of the upright S1 foliation of the Triassic metaturbidites into a NW-SE trending S2 composite foliation dipping to the NE. Transposition is associated with a localized top-to-the-northeast shear zone along the northeastern edge of the DMC and with pervasive top-to-the-southwest shearing from the core to the border of the complex. These structures are consistent with extrusion of the core of the DMC relative to the lower grade Triassic metaturbidites. The position of the biotite isograd overlapping the structural boundary of the DMC suggests that the Triassic metaturbidites have been affected by an increase in temperature as a result of extrusion. Within the DMC, the position of the metamorphic index minerals relative to the composite S2 foliation reveals that biotite, garnet, staurolite and kyanite grew before the transposition into S2, in contrast with sillimanite which crystallizes in the hinge of F2 folds and along the axial planar S2 schistosity. The sillimanite isograd delineates regional-scale overturned F2 folds and cross-cuts the staurolite and kyanite isograds consistent with an increase in temperature during D2. The melt-in isograd characterizes the deepest structural level of the DMC. PT conditions for these metamorphic rocks, determined using pseudosections and conventional thermometry, indicate a temperature increase from 400°C to more than 600°C from the edge to the core of the DMC for a relatively homogeneous pressure ranging from 5 to 6.5kbar suggesting that isograds and isotherms represent the syn-D2 thermal structure of the orogenic crust. Migmatites exposed in the deepest structural level of the DMC yield a pressure significantly lower than the surrounding metamorphic rock suggesting that they crystallized after D2 and after some exhumation of their hosts. Three different types of gneiss domes are distinguished on the basis of their position relative to the isograds, their structural characteristics, and their position relative to the margin of the Yangtze craton. Close to the craton and at the highest structural level, the Gezong dome represents a basement-rooted tectonic slice, in an intermediate position, the Gongcai dome corresponds to a basement-cored nappe, and further away and at the deepest structural level, the Bawang, Cunuchan and Qingaling domes are migmatite-cored domes. The presence at the current-day surface of this variety of gneiss domes reflects the difference in burial of the margin during the Mesozoic Indosinian orogeny.

A combined diffusion and thermal modeling approach to determine peak temperatures of thermal metamorphism experienced by meteorites

Carbonaceous chondrites are affected to different degrees by thermal and aqueous metamorphism on their parent bodies. However, the degree of alteration has been categorized mainly by relative scales and achieving quantitative information about metamorphic temperature by conventional mineral thermometry is problematic for low petrologic types. We have developed a general approach to estimate the metamorphic peak temperature experienced by type 3 chondrites from diffusion zoning in minerals, and have applied this approach to olivine in type I and type II chondrules of CO3 chondrites.To obtain metamorphic temperatures from diffusion zoning, we have combined diffusion modeling with thermal modeling of the meteorite parent body. The integrated diffusion coefficient over time (Γ) was identified as a useful parameter to quantify the extent of chemical change by diffusion occurring in a mineral during a given thermal history. Knowing the temperature dependence of the diffusion coefficient, Γ values can be calculated for each thermal history and be compared to the Γ values obtained from diffusion modeling. For thermal histories realistic for the parent body, Γ depends primarily on the metamorphic peak temperature, so that Γ values determined from diffusion profiles in meteorite minerals can be directly related to the metamorphic peak temperature. This general approach is relatively insensitive to uncertainties in the input parameters for the thermal model.We found that chemical zoning in type I and type II chondrule olivine of the CO chondrites Kainsaz and Lancé was largely influenced by solid state diffusion, which is evident from the observed correlation of zoning anisotropy with the crystallographic orientation. Chemical zoning in type II chondrule olivine is mainly igneous for CO chondrites of petrologic types up to at least 3.2 (Kainsaz) and was influenced only minor by diffusion during parent body metamorphism. Fe–Mg zoning in type II chondrule olivine and around sealed cracks in type I chondrule olivine yields similar Γ values, indicating a formation of both zoning features during a common thermal history on the parent body. In addition, Γ values for type II chondrule olivine correlate with metamorphic grade. The application of this approach on Fe–Mg zoning in type II chondrule olivine of CO3 chondrites yields estimates of maximum metamorphic peak temperatures ranging from 653 to 849K for different petrologic subtypes. The Fe–Mg zoning of type I chondrule olivine is not consistent with the peak temperature estimates from type II chondrule olivine, suggesting an additional contribution of solar nebular processes to type I chondrule olivine zoning prior to accretion into the parent body.

Thermal characterization of carbon nanotube fiber by time-domain differential Raman

Most conventional Raman thermometry for thermal properties measurement is on steady-state basis, which utilizes either Joule heating effect or two lasers configurations coupled with increased complexity of system or measurement uncertainty. In this work, a new comprehensive approach including both transient and steady-state Raman method is proposed for thermal properties measurement of micro/nanowires. The transient method employs a modulated (pulsed) laser for transient heating and Raman excitation, and is termed time-domain differential Raman. The average elevated temperature during the transient heating period is probed simultaneously based on Raman thermometry. Thermal diffusivity can be readily determined by fitting normalized temperature rise against heating time with a transient heat conduction model. On the other hand, thermal conductivity can be obtained in the steady-state measurement by adjusting modulation settings. To verify this method, a carbon nanotube (CNT) fiber is measured with the thermal diffusivity of 1.74−0.20+0.20×10−5 m2/s and the thermal conductivity of 34.3−0.4+0.4 W/m K. The relatively low thermal transport values stem from numerous CNT-glue matrix and CNT–CNT thermal contact resistances. Compared with the conventional steady-state Raman method, the transient method requires no detailed laser absorption value and no temperature coefficient calibration. It can be easily applied to study transient thermal transport in materials.

Initial investigation of a novel noninvasive weight loss therapy using MRI-Guided high intensity focused ultrasound (MR-HIFU) of visceral fat.

MRI-guided high intensity focused ultrasound (MR-HIFU) allows noninvasive heating of deep tissues. Specifically targeting visceral fat deposits with MR-HIFU could offer an effective therapy for reversing the development of obesity, diabetes, and metabolic syndrome. Overweight rats received either MR-HIFU of visceral fat, sham treatment, no treatment, or ex vivo temperature calibration. Conventional MR thermometry methods are not effective in fat tissue. Therefore, the T2 of fat was used to estimate heating in adipose tissue. HIFU treated rats lost 7.5% of their body weight 10 days after HIFU, compared with 1.9% weight loss in sham animals (P = 0.008) and 1.3% weight increase in untreated animals (P = 0.004). Additionally, the abdominal fat volume in treated animals decreased by 8.2 mL 7 days after treatment (P = 0.002). The T2 of fat at 1.5 Tesla increased by 3.3 ms per °C. The fat T2 was 103.3 ms before HIFU, but increased to 128.7 ms (P = 0.0005) after HIFU at 70 watts for 16 s and to 131.9 ms (P = 0.0005) after HIFU at 100 watts for 16 s. These experiments demonstrate that MR-HIFU of visceral fat could provide a safe, effective, and noninvasive weight loss therapy for combating obesity and the subsequent medical complications. Magn Reson Med 76:282-289, 2016. © 2015 Wiley Periodicals, Inc.

Improved k-space-based MR thermometry by joint PRF phase shift and T1/T2* attenuation estimation

MR temperature mapping based on the proton resonance frequency (PRF) shift is used in MR-guided focused ultrasound procedures for dosimetry and safety monitoring. While conventional PRF-shift thermometry is based on calculating a phase difference between two reconstructed MR images, Gaur et al [1,2] have recently described two algorithms that estimate temperature-induced phase shifts directly from MR k-space data, prior to image reconstruction. The approach enables large dynamic scan acceleration factors[1] and the correction of chemical-shift (CS) effects that geometrically distort the temperature maps.[2] However, that work neglected image attenuation that accompanies the PRF phase shift and is primarily caused by increasing T1 with temperature.[3] Here it is shown that attenuation degrades the accuracy of k-space-based reconstructions, but that it can be accounted for in the reconstructions.

Dual echo gradient echo imaging for simultaneous thermal mapping in cortical bone and soft tissue

MRI-guided high-intensity focused ultrasound (MR-HIFU) therapy can relieve pain associated with metastatic and benign bone tumours in patients who fail to respond to conventional radiation therapy. However, since existing MR-thermometry techniques do not provide temperature information within the bone, HIFU exposures in bone are currently monitored using temperature changes in adjacent soft tissues. In this study, a standard dual echo spoiled gradient echo (SPGR) sequence is proposed to monitor thermal effects in both bone and soft tissue simultaneously. Magnitude signal changes at the shorter TE (~1ms) reflect thermal changes in cortical bone, while phase changes at the longer TE (~10ms) allow conventional PRF thermometry in surrounding tissues.

Thermometry via light shifts in optical lattices.

For atoms or molecules in optical lattices, conventional thermometry methods are often unsuitable due to low particle numbers or a lack of cycling transitions. However, a differential spectroscopic light shift can map temperature onto the line shape with a low sensitivity to trap anharmonicity. We study narrow molecular transitions to demonstrate precise frequency-based lattice thermometry, as well as carrier cooling. This approach should be applicable down to nanokelvin temperatures. We also discuss how the thermal light shift can affect the accuracy of optical lattice clocks.

A common high-pressure metamorphic evolution of interlayered eclogites and metasediments from the ‘ultrahigh-pressure unit’ of the Tianshan metamorphic belt in China

Petrological and mineralogical data of interlayered eclogite, marble and quartz–mica schist from a drill core are used to constrain the metamorphic evolution of metavolcanics and intercalated metasediments in the Tianshan (ultra-)high-pressure/low-temperature [(U)HP/LT] metamorphic belt, NW China. The eclogite mainly consists of varying amounts of garnet, omphacite, quartz and zoisite, the marble of calcite (>95vol.%) with minor zoisite and phengite, and the schist of quartz and mica with minor calcite, chlorite, albite and garnet. Using garnet isopleth thermobarometry, pseudosection calculations for the eclogite and quartz–mica schist reveal a common metamorphic evolution under HP condition of both rock types that is also consistent with the temperature estimates for the marble using conventional thermometry. The uniform P–T paths of the interlayered eclogite and quartz–mica schist, as well as compatible temperature data of the marble, document that the whole rock suite constitutes a coherent HP unit during peak metamorphic conditions and exhumation. Thus protoliths of eclogite and associated sediments are believed to have undergone the same metamorphic evolution. In addition, the data gained by the present study of the HP rocks, which were collected in the northern part of the Chinese Tianshan (U)HP/LT belt, do not support the recently proposed tectonic scheme that this metamorphic terrane consists of a northern “coherent UHP unit” and a southern “coherent HP unit”.

Space Measurement System Design and Space Environment Adaptation Experiment of Commercial Sensor DS18B20

In order to solve the problem of the complexity satellite temperature acquisition network cabling connectivity, diversity in temperature acquisition circuits, low temperature acquisition accuracy, complicated computation of temperature formula and so on. A single bus thermometry technology based on 1-wire commercial temperature measurement sensor DS18B20 instead of the conventional thermometry technology on the satellite was proposed. In the study, the space measurement system based on DS18B20 including the design of measurement temperature circuit, software and reliability was designed, and space environment adaptability experiment system was built to study on the temperature measurement performance and spatial adaptation of the commercial sensor DS18B20 in the space environment. The results show that commercial temperature measurement sensor DS18B20 is accurate in a vacuum environment at-50~100°C; the new temperature measurement circuit design makes the temperature collection network cabling easier, and makes solving formula simpler by directly reading the temperature value.

Advancements in Rayleigh scattering thermometry by means of structured illumination

Laser-induced Rayleigh scattering is commonly employed for two-dimensional temperature measurements and offers benefits such as high accuracy, easily interpreted data and low experimental complexity. Yet the approach suffers from an interference often referred to as stray light, an umbrella term used for all spurious light being detected. As Rayleigh scattering is an elastic scattering phenomenon, distinguishing between stray light and the signal of interest is not straightforward. In high-temperature environments, Rayleigh signals are weak due to low molecular densities, which make stray light interferences particularly cumbersome, impairing both the reliability and accuracy of Rayleigh thermometry, especially when applied in harsh combustion environments. In this paper we present an experimental solution to greatly mitigate this issue. The method, Structured Laser Illumination Planar Imaging (SLIPI), employs an intensity modulated laser light sheet to add a recognizable signature to the signal photons. This unique signature allows utilization of a post-processing algorithm that isolates and extracts the desired Rayleigh signal, thereby minimizing measurement uncertainties caused by stray light. The fidelity of the proposed method is first verified by comparing with conventional Rayleigh thermometry under ideal, i.e., stray light-free, measurement conditions. The technique is then employed under more realistic measurement conditions, where the results conclusively illustrate that the current operating range for Rayleigh thermometry can be increased significantly by means of SLIPI.

Temperature of the magnetic nanoparticle microenvironment: estimation from relaxation times

Accurate temperature measurements are essential to safe and effective thermal therapies for cancer and other diseases. However, conventional thermometry is challenging so using the heating agents themselves as probes allows for ideal local measurements. Here, we present a new noninvasive method for measuring the temperature of the microenvironment surrounding magnetic nanoparticles from the Brownian relaxation time of nanoparticles. Experimentally, the relaxation time can be determined from the nanoparticle magnetization induced by an alternating magnetic field at various applied frequencies. A previously described method for nanoparticle temperature estimation used a low frequency Langevin function description of magnetic dipoles and varied the excitation field amplitude to estimate the energy state distribution and the corresponding temperature. We show that the new method is more accurate than the previous method at higher applied field frequencies that push the system farther from equilibrium.

Metamorphic and magmatic overprint of garnet pyroxenites from the Beni Bousera massif (northern Morocco): Petrography, mineral chemistry and thermobarometry

A detailed mineralogical and textural study of two pyroxenites from the Beni Bousera massif, a garnet clinopyroxenite (GP) and a garnet clinopyroxenite containing graphite pseudomorphs after diamond (GGP), indicates a strong metamorphic overprint associated with the massif exhumation. In both pyroxenites, the primary assemblage [Cpx(I)+Gt(I)±Opx] originally stable with diamond, records temperatures in excess of 1200°C. Along the exhumation path, Cpx(I) has decomposed according to the reaction:CpxI=0.55–0.60CpxII+0.30–0.35OpxII+0.03–0.05GtII+0.03–0.5Pl.This breakdown reaction occurred under sub-solidus conditions in at least two stages, which first led to Cpx and Opx exsolution lamellae and second to garnet crystallization at the expense of the newly formed Cpx lamellae. Successive garnet generations, Gt(II), can be distinguished by their REE content; primary garnets Gt(I) have the highest HREE content. Secondary garnets, Gt(II), have grown in the 850–950°C temperature range. We show that these conditions are below the blocking temperature of Mg–Fe exchange between garnet and pyroxene (ca. 1050°C) and above the blocking temperature of Mg–Fe interdiffusion in garnet. Consequently, the original composition of the secondary garnet has not been modified upon further cooling; equilibrium with the appropriate pyroxene can be used to retrieve meaningful P–T conditions. This is however not the case for pairs of pyroxene inclusion and their porphyroclastic garnet host, formed earlier in the Beni Bousera history (i.e. at higher grade) and for which decoupling between Al diffusion and (Mg, Fe) interdiffusion (in pyroxene) has occurred. In that particular case of decoupling, conventional thermometry which yield apparent conditions around 2GPa and 1000–1100°C based on Al-content in pyroxene on one hand and Mg–Fe partitioning between the pyroxenite silicates on the other, will intrinsically fail at providing reliable P and T estimates. Detailed chemical inspection of Gt–Cpx–Opx inclusions in the graphite pseudomorphs indicates that (1) these silicates are genetically related to the same minerals in the bulk rocks and (2) they were chemically isolated from the bulk rock (included in diamond and/or graphite). Finally, the pyroxenite samples from Beni Bousera have recorded two major events pertaining to the late evolution of this massif: (1) the increase of the water activity in GP as shown by the crystallization of pargasitic amphibole which suggests the proximity to crustal units, and (2) a temperature increase up to ca. 1050°C, which led to water-present partial melting of both GP and GGP.

P-T estimates and timing of the sapphirine-bearing metamorphic overprint in kyanite eclogites from Central Rhodope, northern Greece

Sapphirine-bearing symplectites that replace kyanite in eclogites from the Greek Rhodope Massif have previously been attributed to a high-pressure granulite-facies metamorphic event that overprinted the eclogitic peak metamorphic assemblage. The eclogitic mineralogy consisted of garnet, omphacitic pyroxene, rutile and kyanite and is largely replaced by low-pressure minerals. Omphacite was initially replaced by symplectites of diopside and plagioclase that were subsequently replaced by symplectites of amphibole and plagioclase. Garnet reacted during decompression to form a corona of plagioclase, amphibole and magnetite. Rutile was partly transformed to ilmenite and kyanite decomposed to produce a high-variance mineral assemblage of symplectitic spinel, sapphirine, plagioclase and corundum. The presence of quartz and corundum in the kyanite eclogites is evidence for the absence of bulk equilibrium and obviates a conventional analysis of phase equilibria based on the bulk-rock composition. To circumvent this difficulty we systematically explored the pressure-temperature-composition (P-T-X) space of a thermodynamic model for the symplectites in order to establish the pressure-temperature (P-T) conditions at which the symplectites were formed after kyanite. This analysis combined with conventional thermometry indicates that the symplectites were formed at amphibolite-facies conditions. The resulting upper-pressure limit (∼0.7 GPa) of the sapphirine-producing metamorphic overprint is roughly half the former estimate for the lower pressure limit of the symplectite forming metamorphic event. Temperature was constrained (T ∼ 720°C) using garnet-amphibole mineral thermometry. The P-T conditions inferred here are consistent with thermobarometry from other lithologies in the Rhodope Massif, which show no evidence of granulite-facies metamorphism. Regional geological arguments and ion-probe (SHRIMP) zircon dating place the post-eclogite-facies metamorphic evolution in Eocene times.

Peak metamorphic temperatures from cation diffusion zoning in garnet

AbstractA model that relates the characteristic diffusion length and average cooling rate to peak temperature was developed for chemical diffusion in spherical geometries on the basis of geospeedometry principles and diffusion theory. The model is quantitatively evaluated for cation diffusion profiles in garnet. Important model parameters were calibrated empirically using diffusion zoning of Ca in garnet from the Pikwitonei Granulite Domain, a terrane for which the thermal history has been well characterized. The results are used: (i) to empirically test diffusion parameters for Mg and Fe(II) and (ii) to develop a tool that uses the diffusion zoning of these cations in garnet to constrain peak temperature conditions for garnet‐bearing rocks. The thermometric approach was externally tested by applying it to garnet crystals from various metamorphic terranes worldwide and comparing the results to published peak temperature estimates. The results overlap within uncertainties in all cases, but result that are based on Fe(II) and Mg chemical‐diffusion profiles are up to three times more precise than those acquired by conventional methods. The remarkable consistency of the results implies that the model is robust and provides a reliable means of estimating peak temperatures for different types of high‐grade metamorphic rock. The tool could be of particular advantage in rocks where critical assemblages for conventional thermometry do not occur or have been replaced during retrogression.

P-TEstimates and Timing of the Sapphirine-Bearing Metamorphic Overprint in Kyanite Eclogites from Central Rhodope, Northern Greece

Sapphirine bearing symplectites that replace kyanite in eclogites from the Greek Rhodope Massif have previously been attributed to a high pressure granulite facies metamorphic event that overprinted the eclogitic peak metamorphic assemblage. The eclogitic mineralogy consisted of garnet, omphacitic pyroxene, rutile and kyanite and is largely replaced by low pressure minerals. Omphacite was initially replaced by sym plectites of diopside and plagioclase that were subsequently replaced by symplectites of amphibole and pla gioclase. Garnet reacted during decompression to form a corona of plagioclase, amphibole and magnetite. Rutile was partly transformed to ilmenite and kyanite decomposed to produce a high variance mineral assemblage of symplectitic spinel, sapphirine, plagioclase and corundum. The presence of quartz and corun dum in the kyanite eclogites is evidence for the absence of bulk equilibrium and obviates a conventional anal ysis of phase equilibria based on the bulk rock composition. To circumvent this difficulty we systematically explored the pressure temperature composition (P–T–X) space of a thermodynamic model for the symplec tites in order to establish the pressure temperature (P T) conditions at which the symplectites were formed after kyanite. This analysis combined with conventional thermometry indicates that the symplectites were formed at amphibolite facies conditions. The resulting upper pressure limit (~0.7 GPa) of the sapphirine producing metamorphic overprint is roughly half the former estimate for the lower pressure limit of the sym plectite forming metamorphic event. Temperature was constrained (T ~ 720°C) using garnet amphibole mineral thermometry. The P T conditions inferred here are consistent with thermobarometry from other lithologies in the Rhodope Massif, which show no evidence of granulite facies metamorphism. Regional geo logical arguments and ion probe (SHRIMP) zircon dating place the post eclogite facies metamorphic evo lution in Eocene times. DOI: 10.1134/S0869591113050032

Prolactine et cortisol : valeur prédictive chez les polytraumatisés

The Inner Mongolia Suture Zone marks the Paleoproterozoic collisional boundary between the Yinshan Block and Ordos Block in the North China Craton. The ultrahigh-temperature (UHT) orogen developed within this collisional suture reflects the extreme thermal conditions associated with the tectonic processes during the incorporation of the North China Craton within the Columbia supercontinent. Here we report the results from a systematic petrological and phase equilibria modeling study of sapphirine-bearing granulites from Daqingshan, a region within the central domain of the Inner Mongolia Suture Zone. The sapphirine–spinel–garnet–sillimanite–biotite-bearing granulites in Daqingshan occur typically as dark lenses or layers within spinel–garnet–sillimanite–biotite-bearing gneisses, and are associated with mafic granulites carrying orthopyroxene + clinopyroxene + plagioclase + calcic amphibole. The sapphirine in these rocks is magnesian (XMg = 0.73–0.79) and occurs in various microstructural associations such as: (1) matrix coarse-grain mineral in plagioclase aggregates, (2) subidioblastic mineral mantling spinel or in direct contact with spinel, (3) fine-grained phase in sillimanite, and (4) vermicular symplectitic aggregates with plagioclase. Garnet + plagioclase + sapphirine + sillimanite + ilmenite + inferred melt is considered to represent the peak assemblage in these rocks. We apply systematic phase equilibria analysis in the system Na2O–CaO–K2O–FeO–MgO–Al2O3–SiO2–H2O–TiO2–Fe2O3 (NCKFMASHTO) to constrain the peak P–T conditions of the Daqingshan Mg–Al granulites. Our pseudosection analysis defines the stability of the peak assemblage at T > 970 °C at P > 11 kbar. The peak temperature derived from pseudosection analysis is broadly consistent with the temperature estimate from conventional thermometry of sapphirine–spinel pairs (ca. 940 °C). The extreme metamorphism recorded from the Mg–Al granulites from Daqingshan is also consistent with the occurrence of dry orthopyroxene + clinopyroxene + plagioclase, and orthopyroxene + pargasite + plagioclase in the associated mafic granulites, although conventional thermometry yields lower temperatures from these rocks (830–840 °C) marking the post-peak retrograde stage. Our data confirm UHT conditions in Daqingshan and indicate that the extreme metamorphism is of regional extent within the Inner Mongolia Suture Zone, in agreement with the model of ultra-hot metamorphic orogen developed within a Paleoproterozoic subduction–collision system.

Fat‐referenced MR thermometry in the breast and prostate using IDEAL

To demonstrate a three-echo fat-referenced MR thermometry technique that estimates and corrects for time-varying phase disturbances in heterogeneous tissues. Fat protons do not exhibit a temperature-dependent frequency shift. Fat-referenced thermometry methods exploit this insensitivity and use the signal from fat to measure and correct for magnetic field disturbances. In this study, we present a fat-referenced method that uses interpolation of the fat signal to correct for phase disturbances in fat free regions. Phantom and ex vivo tissue cool-down experiments were performed to evaluate the accuracy of this method in the absence of motion. Non-heated in vivo imaging of the breast and prostate was performed to demonstrate measurement robustness in the presence of systemic and motion-induced field disturbances. Measurement accuracy of the method was compared to conventional proton resonance frequency shift MR thermometry. In the ex vivo porcine tissue experiment, maximum measurement error of the fat-referenced method was reduced 42% from 3.3 to 1.9°C when compared to conventional MR thermometry. In the breasts, measurement errors were reduced by up to 70% from 6.4 to 1.9°C. Ex vivo and in vivo results show that the proposed method reduces measurement errors in the heterogeneous tissue experiments when compared to conventional MR thermometry.