Implementation of a new model for pressure dependence of condensed phases in Thermo-Calc

The high pressure modelling of condensed phases has mainly been a topic for geophysics, but there is an interest in modelling moderate pressure dependence also for materials science and engineering. The Murnaghan equation of state has been implemented in the Thermo-Calc software to represent the pressure-dependent part of the Gibbs energy. Recently it has been shown by Jacobs and Oonk that an equation of state derived from an empirical relationship between volume and isothermal bulk modulus can be applied to represent experimental data in volume–pressure–temperature space with equal or better accuracy then the Murnaghan equation of state. In this paper we extend this equation of state and show that a simpler expression for the Gibbs energy can be derived than that given by Jacobs and Oonk. The resulting expression for the Gibbs energy has been implemented in the Thermo-Calc software.     

Use of the time constant to detect corrosion speed in reinforced concrete structures

The relatively simple to measure ‘time constant’ is presented as an index for characterizing the level of corrosion experienced by steel in concrete. This communication, largely in the form of a technical note, explicitly illustrates that the time constant determined from electrochemical testing has significant merit for monitoring corrosion of steel in concrete, and appears to be insensitive to the area of electrode being probed. In this work, the time constant, κ, is determined following a galvanostatic excitation signal, revealing a good correlation between the value of κ and corrosion status across specimens of widely varying geometry. Although this notion has been suggested in the past, this work presents both a survey and consolidated review to indicate the utility of the parameter as an index to corrosion rate on-site.     

南海北部陆缘晚期油气成藏机理及动力学过程

总结了南海北部陆缘晚期(或浅层)油气藏的勘探技术和方法,指出晚期油气成藏具有海底麻坑、气烟囱、"地震模糊带"和"亮点"等地震异常特征,从地化特征上可划分为浅层生物气、成熟—高成熟热解气和高含CO₂热解气等3种油气成藏类型.在研究新构造运动表现形式的基础上,分析了逆断层、正断层和底辟—走滑断层3个断层活动区的晚期油气成藏机理,指出断层晚期活动和后期快速沉降促进了油气的运移和再分配,晚期油气成藏主要沿莺歌海盆地莺东斜坡带、东方—乐东区和沿琼东南盆地二号断裂带及珠江口盆地坳陷边缘斜坡带等分布,有利于油气和天然气水合物的勘探.      

On the involvement of radical oxygen species O− in catalytic oxidation of benzene to phenol by nitrous oxide

Catalytic oxidation of benzene to phenol by nitrous oxide over Fe-MFI zeolites was studied in relation to the active oxygen species taking part in the oxidation. A linear dependence of the reaction rate on the concentration of independently identified active sites generating O⁻ radicals (α sites) was obtained within a broad range of values. The dependence is interpreted as convincing evidence of the O⁻ involvement in the catalytic (not only stoichiometric) oxidation of benzene to phenol. This conclusion is of particular importance in connection with a long discussion in the literature on a possible role of O⁻ radicals in selective oxidation catalysis over V and Mo oxides. Reliable evidence of the catalytic role of O⁻ obtained with zeolites may renew general interest in the once-suggested but not recognized role of radical oxygen in oxidation over widely used metal oxide catalysts.     

Improved electrochemical redox performance of 2,5-dimercapto-1,3,4-thiadiazole by poly(3-methoxythiophene)

High electrocatalytic activity of an electropolymerized film of poly(3-methoxythiophene) (PMOT) is reported toward the redox reaction of 2,5-dimercapto-1,3,4-thiadiazole (DMcT) as a promising cathode material for the lithium ion battery. Cyclic voltammetry showed improved electrochemical performance of DMcT on PMOT-coated Pt electrode, indicating accelerated redox kinetics. Moreover, charge-discharge tests exhibited higher discharge capacity and slower capacity fading of the PMOT-doped DMcT composite cathode compared with pure DMcT.     

Carburization of ferrochromium metals in chromium ore fines containing coal during voluminal reduction by microwave heating

Chromium ore fines containing coal (COFCC) can be rapidly heated by microwave to conduct the voluminal reduction, which lays a foundation of getting sponge ferrochromium powders with a lower content of C. Under the conditions of COFCC with n(O):n(C) (molar ratio) as 1.00:0.84 and n(SiO₂):n(CaO) as 1.00:0.39, the samples were heated by 10 kW microwave power to reach the given temperatures and held for different times respectively. The results show that the low-C-Cr ferrochromium metal phase in the reduced materials forms before the high-C-Cr ferrochromium metal phase does. With increasing temperature the C content of ferrochromium metals is in a positive correlation with the content of Cr. The C content of ferrochromium metal in reduced materials is 0–10.07% with an average value of 4.68%. With the increase of holding time the Cr content in ferrochromium metals is in a negative correlation with the content of C, while the content of Fe changes in the contrary way. In the microwave field the kinetic conditions of carburization are closely related with the temperature of microwave heating, holding time and carbon fitting ratio. Foundation item: Project(50474083) supported by the National Natural Science Foundation of China; Project supported by the Baoshan Iron & Steel Co. Ltd. of China     

江西浒坑钨矿含矿韧性剪切带及其^40Ar-^39Ar年代学约束

江西省浒坑钨矿是一个大型石英脉黑钨矿矿床,含矿石英脉除了块状石英脉以外,还大量发育条带状石英脉。本文针对条带状石英脉进行了专门研究,认为条带状石英脉实质上是韧性剪切带,以透入性发育的剪切面理和拉伸线理、剪切透镜体、剪切分异条带普遍发育为特色。剪切带岩石以石英质糜棱岩为主,具有丰富的塑性变形显微构造特征。显微剪切指向构造统计表明,东西向和北西向脉组的运动方式均以左旋正滑为主,近水平脉组则以正滑为主。北西向韧性剪切带的新生绢云母^40Ar-^39Ar坪年龄为140．3±1．0Ma,相应的等时线年龄为139．6±2．4Ma;而东西向韧性剪切带绢云母^40Ar-^39Ar坪年龄则比较复杂,高温阶段年龄可能受到成矿期白云母残斑的影响,中温阶段的表观年龄和总气体年龄更接近前一样品的坪年龄。据此认为韧性剪切变形的年龄为140Ma左右,韧性变形发生在成岩和成矿之后。条带状石英脉系块状石英脉韧性剪切改造而成,推测其形成主要与晚期补充岩体的斜向上侵作用有关,但更为合理的模式需要更多资料的进一步证实。     

Variability of sedimentary phosphorus fractions in the western and Sandusky basins of Lake Erie

Surface sediments and three sediment cores from the western basin and one sediment core from the Sandusky basin were analyzed to document spatial and temporal changes in five phosphorus fractions and total phosphorus (TP). The areal distributions of the bioavailable fractions NaCl-Pi, NaBD-Pi, and NaOH-Pi and the refractory organic fraction Res-P were broadly consistent and contrasted with those of the detrital fraction HCl-Pi which showed that high concentrations occurred mostly in high-energy littoral zones and low concentrations largely in profundal depositional areas. The contrasting distributions were induced by interactions among tributary inputs, wave action, circulation, and biogeochemical cycling and transfer in the basin. As revealed by the Sandusky basin sediment record, the detrital fraction HCl-Pi was dominant (70% of TP) during European settlement and decreased rapidly by 28.0% in the early 1910s due largely to impoundments of the Maumee and Sandusky Rivers. While HCl-Pi has ever since remained relatively constant, NaCl-Pi, NaBD-Pi, and NaOH-Pi increased significantly between 1950 and 1970 in the two basins. However, the post-regulation sediment records differed considerably among these coring sites. There was a marked increase of TP in two cores, corresponding to recent return of eutrophication and massive harmful algal blooms but contrasting with a relatively constant, low loading into the lake. This signified the role of internal loading as derived partialy from legacy pollution. Furthermore, NaCl-Pi has increased progressively throughout all the records. We conclude that the increased levels of NaCl-Pi in surface sediments may have altered the internal loading and contributed to the resurgences of harmful algal blooms in Lake Erie.     

Global estimates of evapotranspiration and gross primary production based on MODIS and global meteorology data

The simulation of gross primary production (GPP) at various spatial and temporal scales remains a major challenge for quantifying the global carbon cycle. We developed a light use efficiency model, called EC-LUE, driven by only four variables: normalized difference vegetation index (NDVI), photosynthetically active radiation (PAR), air temperature, and the Bowen ratio of sensible to latent heat flux. The EC-LUE model may have the most potential to adequately address the spatial and temporal dynamics of GPP because its parameters (i.e., the potential light use efficiency and optimal plant growth temperature) are invariant across the various land cover types. However, the application of the previous EC-LUE model was hampered by poor prediction of Bowen ratio at the large spatial scale. In this study, we substituted the Bowen ratio with the ratio of evapotranspiration (ET) to net radiation, and revised the RS-PM (Remote Sensing-Penman Monteith) model for quantifying ET. Fifty-four eddy covariance towers, including various ecosystem types, were selected to calibrate and validate the revised RS-PM and EC-LUE models. The revised RS-PM model explained 82% and 68% of the observed variations of ET for all the calibration and validation sites, respectively. Using estimated ET as input, the EC-LUE model performed well in calibration and validation sites, explaining 75% and 61% of the observed GPP variation for calibration and validation sites respectively.Global patterns of ET and GPP at a spatial resolution of 0.5° latitude by 0.6° longitude during the years 2000-2003 were determined using the global MERRA dataset (Modern Era Retrospective-Analysis for Research and Applications) and MODIS (Moderate Resolution Imaging Spectroradiometer). The global estimates of ET and GPP agreed well with the other global models from the literature, with the highest ET and GPP over tropical forests and the lowest values in dry and high latitude areas. However, comparisons with observed GPP at eddy flux towers showed significant underestimation of ET and GPP due to lower net radiation of MERRA dataset. Applying a procedure to correct the systematic errors of global meteorological data would improve global estimates of GPP and ET. The revised RS-PM and EC-LUE models will provide the alternative approaches making it possible to map ET and GPP over large areas because (1) the model parameters are invariant across various land cover types and (2) all driving forces of the models may be derived from remote sensing data or existing climate observation networks.