An experimental study of dehydration melting of phengite-bearing eclogite at 1.5―3.0 GPa

Dehydration melting experiments were performed on ultrahigh-pressure eclogite from Bixiling in the Dabie orogen at 1.5--3.0 GPa and 800--950℃ using piston cylinder apparatus. The results show that （1） eclogite with -5% phengite started to melt at T≤800--850℃ and P = 1.5--2.0 GPa and produced about 3% granitic melt; （2） the products of dehydration melting of phengite-bearing eclogite vary with temperature and pressure. Fluid released from dehydration of phengite and zoisite leads to partial melting of eclogite and formation of plagioclase reaction rim around kyanite at pressures of 1.5--2.0 GPa and temperatures of 800--850℃; （3） phengite reacted with omphacite and quartz and produced oligoclase, kyanite and melt at elevated temperatures. Oligoclase is the primary reaction product produced by partial melting of phengite in the eclogite; and （4） the dehydration melting of phengite-bearing eclogite at pressures of 1.5--3.0 GPa and temperatures ≥900℃ results in formation of garnets with higher molar fraction of pyrope （37.67 wt.%--45.94 wt.%）. Potassium feldspar and jadeite occur at P = 2.4--3.0 GPa and T≥900℃, indicating higher pressure and fluid-absent conditions. Our results constrain the solidus for dehydration melting of phengite-bearing eclogite at pressures of 1.5--3.0 GPa. Combining experi- mental results with field observations of partial melting in natural eclogites, we concluded that phengite-bearing eclogites from the Dabie-Sulu orogen were able to partially molten at P= 1.5--2.0 GPa and T= 800--850℃ during exhumation. The ultrahigh-high pressure eclogites would have experienced partial melting in association with metamorphic phase transformation under different fluid conditions.     

Vp of muscovite-biotite gneiss up to 950℃ at 400 MPa: Constraints on the origin of abnormal seismic layers in continental crust

Here we present experimental results of compressional wave velocity (Vp) of muscovite-biotite gneiss from Higher Himalayan Crystallines (HHC) at the temperature up to 950℃ and the pressure of 0.1―400 MPa. At 400 MPa, when the temperature is lower than 600℃, Vp decreases linearly with increasing temperature at the rate of (Vp/T)p -4.43×10-4 km/s ℃. In the temperature range of 600―800℃, Vp drops significantly and the signal is degraded gradually due to the dehydration of muscovite and α-quartz softening. When the temperature rises from 800℃ to 875℃, Vp increases and the signals become clear again as a result of the temperature going through the β-quartz range. The experiments indicate that the duration has great influence on the experimental results when temperature is above the dehydration point of biotite. During the first 30 h at 950℃, the Vp decreases substantially from 5.9 to 5.4 km/s and the signal amplitude is attenuated by more than 80%. After the 30-h transition, the Vp and the amplitude of ultrasonic wave signals become steady. The decrease of Vp and attenuation of the signals at 950℃ are associated with the breakdown reactions of biotite. The experiments suggest that the breakdown of muscovite and/or quartz softening can contribute to the low seismic wave velocity in thickened quartz-rich felsic-crust such as what is beneath southern Tibet. Additionally, α-β quartz transition generates a measurable high seismic velocity zone, which provides a possibility of precisely constraining the temperature in the upper-middle continental crust. Our study also demonstrates that duration is a key factor to obtain credible experimental results.     

An experimental study on the solubility of copper bichloride in water vapor

Using the solubility method, the solubility of CuCl2 in liquid-undersaturated HCl-bearing water vapor was investigated experimentally at temperatures of 330-370 ℃ and pressures of 4.2-10 MPa. The re-sults have shown that hydration could significantly enhance copper solubility and the concentrations of copper were positively correlated with PH2O. The solubility of copper in vapor phase increased with increasing PH2O at the constant temperature. CuCl2 was transported as hydrated species CuCl2(H2O)ngas in water vapor. The formation of complexes is proposed to be the result of the following reaction: CuCl2solid nH2Ogas = CuCl2 (H2O)ngas The hydration number n decreased slightly with increasing temperature. Statistical hydration numbers are 4.0, 3.6 and 3.3 at 330, 350 and 370 ℃ , respectively.     

New Early Triassic paleomagnetic data from Huangben section, Guangdong and its tectonic implications

Continent China is composed of several blocks of variable sizes during different geological times, inwhich South China Block is composed of three tectonic units: Yangtze Block, Jiangnan Fold Belt and Southeast China Coastal Fold Belt (Fig. 1(a)), the last…     

Microwave sintering of Ca<Subscript>0.6</Subscript>La<Subscript>0.2667</Subscript>TiO<Subscript>3</Subscript> microwave dielectric ceramics

Ca_0.6La_0.2667TiO₃ ceramics were prepared by conventional and microwave sintering techniques and their sinterability, microstructure, and microwave dielectric properties were investigated in detail for comparison. Densified Ca_0.6La_0.2667TiO₃ ceramics were obtained by microwave sintering at 1350°C for 30 min and by conventional sintering at 1450°C for 4 h. An unusual phenomenon was found that some larger grains (grain size range: 8–10 μm) inclined to assemble in one area but some smaller ones (grain size range: 2–4 μm) inclined to gather in another area in the microwave sintered ceramics. The microwave dielectric properties of Ca_0.6La_0.2667TiO₃ ceramics prepared by microwave sintering at 1350°C were as follows: dielectric constant (ɛ _r) = 119.6, quality factor (Qf) = 17858.5 GHz, and temperature coefficient of resonant frequency (τ _f) = 155.5 ppm/°C. In contrast, the microwave dielectric properties of the ceramics prepared by conventional sintering at 1450°C were ɛ _r = 117.4, Qf = 13375 GHz, and τ _f = 217.2 ppm/°C.     

Dispersion of CoCl2 into γ-Al2O3 studied by positron

Co²⁺/γ-Al₂O₃ samples were prepared by incipient wetness impregnation of γ-Al₂O₃ with different concentration solution of CoCl₂ and dried at 40 °C. We measured the positron lifetime spectra of the samples of different Co²⁺ mass fractions (0%–8.24%) heated at different temperatures (100–500°C). All lifetime spectra were resolved into four components, in which the third and the fourth components were related to the surface state of the micropores and the secondary pores of the γ-Al₂O₃. The experimental results showed that the Co²⁺ was mainly located in the micropores and the secondary pores near to the exterior of the support. For low Co²⁺ mass fraction samples, when the heating temperature was above 400 °C, dispersal was almost finished. When the Co²⁺ mass fraction was above 5.59%, Co²⁺ and Cl⁻ were dispersed into the secondary pores in the form of multiple layers.     

Microstructure evolution and phase transformation of traditional cast and spray-formed hypereutectic aluminium-silicon alloys induced by heat treatment

Microstructural evolution and phase transformation induced by different heat treatments of the hypereutectic aluminium-silicon alloy, Al-25Si-5Fe-3Cu (wt%, signed as 3C), fabricated by traditional cast (TC) and spray forming (SF) processes, were investigated by differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) combined with energy dispersive X-ray spectroscopy and X-ray diffraction techniques. The results show that Al₇Cu₂Fe phase can be formed and transformed in TC- and SF-3C alloys between 802–813 K and 800–815 K, respectively. The transformation from β-Al₅FeSi to δ-Al₄FeSi₂ phase via peritectic reaction can occur at around 858–870 K and 876–890 K in TC- and SF-3C alloys, respectively. The starting precipitation temperature of δ-Al₄FeSi₂ phase as the dominant Fe-bearing phase in the TC-3C alloy is 997 K and the exothermic peak about the peritectic transformation of δ-Al₄FeSi₂→β-Al₅FeSi is not detected in the present DSC experiments. Also, the mechanisms of the microstructural evolution and phase transformation are discussed.     

Influence of isothermal aging on σ precipitation in super duplex stainless steel

The time-temperature-transformation (TTT) curve of the 00Cr25Ni7Mo4N duplex stainless steel was obtained with a Formastor-digital thermal dilatometer, and the influence of isothermal aging on σ precipitation was studied by metallographic observation, X-ray diffraction (XRD), and transmission electron microscopy (TEM). The results show that the decomposition of ferrite phase is accompanied by the formation of σ phase at 750–1000℃, especially in the range of 800–900℃. The longer the aging time, the higher the amount of σ precipitation. The area fraction of various phases remains at a certain value upon the completion of ferrite deformation. The temperature of 850℃ is the most sensitive transaction temperature, the incubation time for the formation of σ precipitation is less than 1 min, and aging for 20 min leads to the complete transformation of ferrite. The σ phase is formed preferentially at the α/α/γ junction, and then grows along the α/α boundary in the matrix.     

Ultrahigh-pressure (4.5–5.5 GPa) experimental research on pyroxene-garnet transition and its significance

Conclusions The transition from natural Al-enstatite to garnet and Al-poor pyroxene has taken place under the condition of about 1000°C and 4.5–5.5 GPa, and new phases of garnet and corundum have formed when 15% Al₂O₃ was added to the initial natural Al-enstatite. This experimental result has explained the ultrahigh pressure (3.5–5.0 GPa) and relatively low temperature (< 1000°C) genesis of the ultramafic rock of high-pressure metamorphic zone in Dabieshan-northern Jiangsu-Jiaodong and of red corundum garnetite coexisting with garnet peridotite. From the genetic mineralogy, petrology andP-T equilibrium conditions of garnet peridotite of the high-pressure metamorphic zone, kimberlite and Cenozoic basalt and the ultrahigh pressure experimental result, it is inferred that the upper mantle garnet peridotite is transformed with the increase of depth from Al-rich pyroxene garnet peridotite (80–120 km) to Al-poor pyroxene garnet peridotite (greater than 120–150 km).     

Organic solvent- and phase transfer catalyst-free oxidation of cyclohexanol to cyclohexanone with dilute H2O2

The oxidation of cyclohexanol to cyclohexanone with 30% aqueous hydrogen peroxide by using peroxotungstate complexes formed in situ from sodium tungstate dihydrate and various bidentate organic ligands as the catalysts, without organic solvents, halide and phase transfer catalyst has been carried out. The influence of 13 ligands on the oxidation is investigated. The maximum yield of cyclohexanone is obtained when using 1,10-phenanthroline (96%) and oxalic acid (95%) as the ligand. Very high yields (around 90%) have also been obtained for the instances of using salicylic acid, 3,5-dibromosalicylic acid, and 8-hydro- xylquinoline as ligands. A research to improve the reaction condition using cheap oxalic acid as the ligand indicates that the optimum condition is that the reaction mixture with a molar ratio of cycohexanol︰tungstate dihydrate︰oxalic acid︰30% H₂O₂=100︰2︰2︰120 was stirred at 85—90℃ for 12 h. :     

Myoglobin as Mimetic Enzyme and Its Analytical Application in Determination of H2O2

0 IntroductionSltougdiiceasl csoynstceermnsin gharveeac btieveen o txhyeg ei nm psopretcaienst ( oRbjOecSt) iinn bbiioo--medicine and analytical chemistry in recent years[1-4]. Manyi mportant life phenomena and diseases are relatedtotheinter-mediates of ROS[5-7].ROS have beeni mplicated as ani mpor-tant causative factor in cell damage,including apoptosis andnecrosis . Their proposed actions comprise lipid peroxidation,DNAdamage,the mitochondrial respiratory chain destructionand protein mo…     

Synthesis and characterization of monoclinic TiO<Subscript>2</Subscript> nanosheets

A novel two-step method for the synthesis of monoclinic titanium oxide （i.e. TiO2（B）） nanosheets is presented in this report. The method is featured by two steps： 1） synthesis of hydrogen titanate nanosheets, followed by 2） calcination of the titanate nanosheets at elevated temperatures. The hydrogen titanate nanosheets were prepared first by autoclaving anatase TiO2 powders, obtained by air cal- cining an ethanol-gel of Ti（OH）4 at 500℃, in aqueous NaOH （10 mol/L） at 150-200℃, and then by washing with hydro- chloric acid under supersonic irradiation. While sizes of the nanosheets were found to increase with increasing the temperature of the hydrothermal treatment, the calcination at 400-500℃ of the hydrogen titanate nanosheets that were synthesized at higher autoclaving temperatures （180-200℃） produced monoclinic TiO2 nanosheets with a uniform morphology. By contrast, the same calcination of the titanate nanosheets synthesized at the autoclaving temperature 180℃ led to anatase TiO2 nanoparticles.     

Reconstructing temperature change in Central East China during 601–920 AD

Using historical records on first and last frost and snow, spring cultivation, David peach blossom, autumn crop harvest, grade of sea freeze and change in northern citrus boundary, we reconstructed temperature change during 601–920 AD. The mean temperature of the winter half-year (October to April) over Central East China during this period was about −0.22°C higher than that of the present (1961–2000 AD mean). During 601–820 AD, mean temperature was about −0.52°C higher than the present. During 821–920 AD, the mean temperature was 0.42°C lower than the present. The temperature fluctuations were characterized by a maximum amplitude of 1.05°C at the centennial scale, 1.38°C at the 50–year scale, 2.02°C at the 30-year scale, and 2.3°C at the 20-year scale. There were four peaks warmer than today (601–620 AD, mean of 1°C higher temperature; 641–660 AD, 1.44°C; 701–720 AD, 0.88°C; 781–800 AD, 0.65°C). Three cold periods were in 741–760, 821–840, and 881–900 AD, the mean temperature of which was 0.37–0.87°C lower than the present.     

Preparation by a rheological phase reaction method and thermal decomposition reaction mechanism of nickelous salicylate tetrahydrate

0　IntroductionInrecentyears,studiesonBinghamfluid ,suchasElec trorheologicalfluid ,areactivelypursued[1 6] .Rheologicaltechniqueshavebeenplayinganimportantroleinsyntheticchem istry .Therheologicalphasereactionmethodisthe processofpreparingcompoundsormaterialsfromasolid liquidrheologicalmixture.Thatis,thesolidreactantsarefullymixedinapropermolarratio ,andmadeupbyaproperamountofwaterorothersolventstoaBinghambodyinwhichthesolidparticlesandliquidsubstanceareuniformlydistributed ,sothattheprodu…     

Temperature effects on ethylene and methane production from temperate forest soils

Change in temperature affects the activity of soil microorganisms.However,there is limited knowledge about temperature effects on ethylene(C2H4) and methane(CH4) production from forest soils.Topsoil samples(0―5 cm) collected from different temperate forest stands(e.g.,Pinus sylvestris L.,Cryptomeria japonica,and Quercus serrata) were used to compare C2H4 and CH4 production from soils at temperature from 5 to 35℃ under oxic and anoxic conditions.The rates of C2H4 and CH4 production from soils under oxic cond...     

Extraction of Aluminum and Iron from Boiler Slag by Sulfuric Acid

This paper presents a new method of recycling aluminum and iron in boiler slag derived from plants that use coal as fuel. The new method integrates efficient extraction and reuse of the leached pellets together. An elemental analysis of aqueous solutions leached by sulfuric acid was determined by EDTA-Naz-ZnCl2 titration method. The components and microstructures of the samples were examined by means of XRF, XRD and SEM. An aluminum extraction efficiency of 86.50% was achieved when the sintered pellets were leached using 4 mol · L^- 1 H2SO4 at solid/ liquid [m（g）/V（mL）] ratio of 1 ： 5 at 80 ℃ for 24 h. An iron extraction efficiency of 94.60% was achieved in the same conditions for the maximum extraction efficiency of Al. The extraction efficiencies of Al and Fe increased with an increase in temperature, leaching time and acidity. The concentration of alumina and iron hydroxide in the final product was determined to be 99.12% and 92.20% respectively. This product of alumina would be used directly for the production of metallic aluminum.     

Synthesis mechanism of LiNiVO4 by wet chemical method and mixed valence of nickel and vanadium

The single phase LiNiVO₄ has been successfully synthesized by adopting a new mild liquid route with oxalic acid as both complexant and precipitant, and this method is named the CPG method. The products were obtained by sintering the dry gel precursor which was prepared by the CPG method at 200—850℃ for 2—10 h in air. The products were tested by XRD, XPS, ESR and TGA-DTA, and the results indicate that the single phase LiNiVO₄ could be obtained at 450℃ for 2—3 h in air and LiNiVO₄ was still steady at 850℃ for 10 h. The valence analyses show that in LiNiVO₄ the valence of lithium is +1, both nickel and vanadium have the mixed valence, namely +2, +3 for nickel and +4, +5 for vanadium respectively. The LiNiVO₄ can be expressed as LiNi³⁺_xNi²⁺_1-xV⁴⁺_xV⁵⁺_1-xO₄ (0≤x<1). The pyrolysis mechanism of the dry gel is also discussed.     

Kinetic study of the hydrocarbon generation from marine carbonate source rocks characterization of products of gas and liquid hydrocarbon

The kinetic parameters of hydrocarbon generation from the marine carbonate source rocks were determined and calibrated through kinetic simulating experiment. The kinetic parameters of hydrocarbon generation then were extrapolated to geological condition by using the relative software. The result shows that gaseous hydrocarbons (C_1, C_2, C_3, C_(4-5)) were generated in condition of 150℃相似文献   

Cretaceous synfolding remagnetization components revealing tectonic rotation of the middle Yangtze fold belt

To reveal the deformation process of the middle Yangtze fold belt, we conducted a paleomagnetic study on Middle Triassic limestones and Middle to Late Jurassic sandstones from Wanzhou, Chongqing. Stepwise thermal and alternating field demagnetization were used to isolate the multi-component re-manent magnetizations. The Jurassic samples were overprinted by recent geomagnetic field, while three magnetization components were isolated from the Middle Triassic samples. A low temperature component (LTC) was isolated at temperatures below 200℃, an intermediate temperature component (ITC) at 200―360℃ and a high temperature component (HTC) at 400―460℃. The LTC is distributed around the present-day Earth magnetic field, probably a viscous component. Stepwise unfolding indi-cates that the maximum precision parameters of ITC and HTC components are achieved at 33±8% and 50±27% (with 95% confidence) unfolding, respectively. The best-clustered ITC mean direction, Dec = 11.2°, Inc = 45.2° (α₉₅ = 4.5°, N = 34), corresponding to a paleopole at 79.3°N, 219.5°E (d_p = 3.6°, d_m = 5.7°), is consistent with the Cretaceous reference direction of the South China Block (SCB). The best-clustered HTC mean direction (taking 70% unfolding), Dec = 24.2°, Inc =49.0° (α₉₅ = 3.6°, N = 23), corresponding to a paleopole at 69.2°N, 195.5°E (d_p =3.1°, d_m = 4.8°), suggests a clockwise rotation of 12.8°±3.5°. These synfolding remagnetization components clearly reveal that a clockwise rotation happened at the middle stage of folding, thus supporting that at least part of the variation in fold axis strikes is due to orocline rotation. Combined with published data, our analysis indicates that the Wan-zhou-Xiangxi segment of the middle Yangtze fold belt experienced oroclinal bending. Furthermore, a published post-folding component isolated from the Middle Triassic Puqi Formation suggests a 27.5°±5.8° clockwise rotation, confirming that at least 50% of the observed clockwise rotations in the eastern middle Yangtze fold belt can be attributed to oroclinal bending. The remagnetization data and geological evidence observed in the middle Yangtze fold belt suggest that collision between SCB and North China Block (NCB) probably lasted till the early period of Early Cretaceous.     

CeO2 thin films grown on biaxially textured nickel (001)

CeO\-2 films have been grown on biaxially textured Ni substrates at various temperatures. The results show that CeO\-2 films without IBAD are dominated by (111) orientation from room temperature to 800℃ while the preferential orientation of CeO\-2 films with IBAD is (001) at lower deposition temperature and (111) at deposition temperature higher than 450℃. CeO\-2 films with better in_plane texture and out_of_plane orientation can be grown at 360℃ with 240 eV ion energy and 200 μA/cm\+2 ion current density.