Viscosity-temperature relationships in the system Na2Si2O5-Na4Al2O5

The viscosity-temperature relationships of five melts on the join Na₂Si₂O₂-Na₄Al₂O₅ (5, 10, 20, 30 and 40 mole percent Na₄Al₂O₅) have been measured in air, at 1 atm and 1000–1350°C with a concentric cylinder viscometer. All the melts on this join of constant bulk polymerization behave as Newtonian fluids, in the range of shear rates investigated, and the melts exhibit Arrhenian viscosity-temperature relationships.Isothermal viscosities on this join initially decrease and then increase with increasing mole percent Na₄Al₂O₅. The minimum viscosity occurs near 20 mole percent Na₄Al₂O₅ at 1000°C and moves to higher Na₄Al₂O₅ content with increasing temperature.The observation of a viscosity minimum along the join Na₂Si₂-O₅-Na₄Al₂O₅ is not predicted based on earlier viscosity data for the system Na₂O-Al₂O₃-SiO₂ (RlEBLlNG, 1966) or based on calculation methods derived from this and other data (Bottinga and Weill, 1972). This unexpected behavior in melt viscosity-temperature relations emphasizes the need for a more complete data set in simple silicate systems.Previous spectroscopic investigation of melts on the join Na₂2Si₂O₅-Na₄Al₂O₅ offer a structural explanation for the observed viscosity data in terms of a disproportionation reaction involving polyanionic units. Macroscopically, the viscosity data may be qualitatively reconciled with the configurational entropy model for viscous flow (Richet, 1984).     

MIS 5a/5b时期亚洲夏季风变化的高分辨率石笋记录

由于深海氧同位素阶段5时期 (Marine Isotope Stage 5, MIS 5)高分辨率的亚洲夏季风记录较少,限制了对该时期亚洲夏季风变化的认识。本文利用重庆金佛山羊口洞石笋的δ18O记录,重建了MIS 5a/5b时期平均分辨率为38年的亚洲夏季风演变历史。发现该时段亚洲夏季风在千年—百年尺度上与北大西洋地区气候变化存在紧密联系。得益于误差小于0.4%的230Th测年结果,本文标定了中国间冰阶(Chinese Interstadial, CIS)21的开始时间为84.6±0.3 ka BP,CIS 22的起止时间分别为91.2±0.3 ka BP和88.9±0.3 ka BP。此外,羊口洞石笋记录的CIS 21和CIS 22的变化模式与格陵兰记录不同,而与南极冰芯记录呈反相对应,可能表示在此阶段亚洲夏季风受到了南半球气候变化的影响。      

SPOT5卫星影像在矿山环境调查中的应用

以吉林省辽源市煤炭矿山为研究对象,通过对SPOT5卫星影像纠正、融合、解译等处理,快速、便捷地查清矿区的地质环境问题:矿区固体废物堆放、尾矿库分布情况;矿山采空区地面塌陷、山体开裂、滑坡、崩塌、泥石流、岩溶塌陷、煤田自燃等地质灾害分布情况;由矿产开发引发的水土流失、土地沙化、侵占土地、植被破坏的情况;矿区水体、植被、土壤污染状况等。通过矿山地质环境调查实践,总结出了SPOT5卫星影像最优波段组合、融合方法及矿山地质环境调查中的地物判读标志,从而使SPOT5卫星影像在遥感环境地质调查中发挥了重要作用。     

Panel 5: Chemical processes at the ocean bottom

Novel techniques and existing knowledge from chemical research that could be applied to understanding processes at the ocean bottom are by and large analytical, but not entirely. Microelectrodes developed for both the study of electron transfer at interfaces and for application in medical research could be readily modified to investigate gradients at the sediment-water interface. The body of knowledge assembled for, and derived from, election transfer research should be a valuable resource of understanding the mechanisms of redox reactions that occur in the ocean. Chemiluminescent methods for measuring metals in seawater would become much more generally applicable if additional luminescing compounds that chelate metals with great specificity could be identified or synthesized. Collaboration with analytical chemists might enable the development of this method to a wide variety of marine analytical problems. Recent advances in optical detector technology should catalize the adaptation of chemiluminescent methods to in situ analysis.A variety of separation techniques developed for chemical research could be applied to the problems of separating both dissolved and particulate organic matter from their natural matrices. If this can be accomplished it will remove a major barrier in the characterization of organic matter in the ocean. A potential approach for determining the biochemical character of this material after separation is degradation using bacterial enzymes, and then identification of subunits of the polymers by techniques such as ¹³C-NMR.Relatively recent application of GC-MS and high pressure liquid chromatography to marine organic analysis has already produced more data than is interpretable by marine organic chemists. Chemometric and statistical methods developed by chemists to maximize data interpretation could be used to interpret large data sets plan future experimental approaches.High analytical precision and extremely low detection limits are prerequisites for solving many of the problems associated with hydrothermal circulation and paleoceanography. Some examples of emerging analytical methodology for improving these are echelle spectrography coupled with highly sensitive charge transfer device detectors to enable determination of elemental ratios at high precision, and ICP-mass spectrometry which achieves very low detection limits for some elements.     

Westward accretion of the Baltic Shield: implications from the 1.6 GaÅmål-Horred Belt, SW Sweden

Three new U-Pb zircon age determinations are reported from the Horred region, south-southeast of Göteborg, SW Sweden. This is a region of the Southwest Scandinavian Domain, within which a major NS trending shear zone and tectonic boundary, the Mylonite Zone, juxtaposes comparatively weakly migmatised lithologies in the west against more intensely migmatised gneisses in the east.West of the Mylonite Zone, a metavolcanic rock (the Mjösjödacite) yields an age of 1643 ± 29 Ma, whereas a cross-cutting plutonic rock (the Idala tonalite) has an age of 1584 ± 15 Ma. Together with a recent age for a volcanic rock from theÅmål region farther north (1.61 Ga, Lundqvist and Skiöld, 1992), these ages help to establish the existence of a coherent calc-alkaline igneous belt of 1.6 Ga age for which the nameÅmål-Horred Belt is proposed.East of the Mylonite Zone, a presumably metavolcanic rock (the Grimmared gneiss) yields an age of 1.61 Ga. The obtained age and the compositional similarity of rocks on each side of the Mylonite Zone indicate that more deformed and more strongly metamorphosed equivalents of the rocks in theÅmål-Horred Belt may occur also to the east of the Mylonite Zone in what is termed the Eastern Segment of the Southwest Scandinavian Domain.The new results establish theÅmål-Horred Belt as a major geological unit younger than most other crustal components in southern Sweden such as theÖstfold-Marstrand Belt ( 1.76 Ga), the Eastern Segment gneisses (> 1.66 Ga) and the three age groups of the Transscandinavian Igneous Belt ( 1.81 – 1.65 Ga; Larson and Berglund, 1992). The configuration of the crustal units in SW Sweden appears to necessitate more complex Proterozoic models than those with a persistent younging from the present east to the west.The present concept of the “Gothian orogeny” must be revised since at least two different orogenic episodes at 1.7 and 1.6 Ga can now be distinguished.     

Dislocation strain energy in the Al2SiO5 polymorphs

Molar elastic strain energy arising from dislocations in andalusite and sillimanite were calculated using equations derived from a non-core, linear elasticity model. For perfect (unit) c screw dislocations in these polymorphs, minimum dislocation densities of about 10¹⁰/cm² are necessary to significantly perturb the andalusite=sillimanite equilibrium boundary in P-T space. Compared to unit c dislocations, smaller energy perturbations arise from dissociated c screw dislocations, which are commonly observed in kyanite and sillimanite. A low computed value of stacking fault energy (～30 ergs/cm²) in these polymorphs is compatible with the large separations of dissociated dislocations in these phases. Dislocation densities in naturally occurring Al₂SiO₅ polymorphs are typically <10⁸/cm². Assuming that these densities are representative of those existing during metamorphism, as is supported by the lack of microtextures indicative of strong recovery, it is concluded that molar strain energies corresponding to observed dislocation densities (<10⁸/cm²) result in insignificant perturbation of P-T phase equilibrium boundaries of the Al₂SiO₅ polymorphs.     

ELF isosurface maps for the Al2SiO5 polymorphs

This study examines the electron localization function (ELF) isosurfaces of the Al₂SiO₅ polymorphs kyanite, sillimanite, and andalusite to see how differences in coordination and geometry of the cations and anions affect the ELF isosurfaces. Examination of the ELF isosurfaces indicates that their shapes are dependent on the coordination and geometry of the oxygen atoms and are not sensitive to coordination of the surrounding cations. Of the 18 crystallographically distinct oxygen atoms in the Al₂SiO₅ polymorphs, 13 are bonded to two aluminum atoms and one silicon atom (Al₂–O–Si) and are associated with two different ELF isosurface shapes. The shape of the ELF isosurface is dependent on the distance at which the oxygen atom lies from a plane defined by the three surrounding cations: at a distance greater than 0.2 Å the ELF can be defined as horseshoe-shaped and at a distance less then 0.2 Å it can be described as concave hemispherical. This feature is also seen in the ELF isosurfaces for the oxygens bonded to three aluminum atoms (Al₃–O) where the isosurfaces can be defined as trigonally toroidal and uniaxially trigonally toroidal. The changes in the ELF isosurfaces for the three coordinated oxygens are also indicative of changes in hybridization. The ELF isosurface for the two-fold coordinated oxygen (Al–O–Si) has a large mushroom-shaped isosurface along the Al–O bond and a concave hemispherical isosurface along the Si–O. The four-fold coordinated oxygen (Al₄–O) contains two concave hemispherical isosurfaces along the shorter Al–O bonds and a banana-shaped isosurface, which encompasses the longer Al–O bonds. In addition, this study shows the homeomorphic relationship between the ELF isosurfaces and electron density difference maps with respect to number and arrangement of domains.     

Contents to Volume 5

Volume Contents

Contents to Volume 5     

Thermodynamic data of the high-pressure phase Mg5Al5Si6O21(OH)7 (Mg-sursassite)

 Calorimetric and P–V–T data for the high-pressure phase Mg₅Al₅Si₆O₂₁(OH)₇ (Mg-sursassite) have been obtained. The enthalpy of drop solution of three different samples was measured by high-temperature oxide melt calorimetry in two laboratories (UC Davis, California, and Ruhr University Bochum, Germany) using lead borate (2PbO·B₂O₃) at T=700 ^∘C as solvent. The resulting values were used to calculate the enthalpy of formation from different thermodynamic datasets; they range from −221.1 to −259.4 kJ mol⁻¹ (formation from the oxides) respectively −13892.2 to −13927.9 kJ mol⁻¹ (formation from the elements). The heat capacity of Mg₅Al₅Si₆O₂₁(OH)₇ has been measured from T=50 ^∘C to T=500 ^∘C by differential scanning calorimetry in step-scanning mode. A Berman and Brown (1985)-type four-term equation represents the heat capacity over the entire temperature range to within the experimental uncertainty: C _P (Mg-sursassite) =(1571.104 −10560.89×T ^−0.5−26217890.0 ×T ⁻²+1798861000.0×T ⁻³) J K⁻¹ mol⁻¹ (T in K). The P V T behaviour of Mg-sursassite has been determined under high pressures and high temperatures up to 8 GPa and 800 ^∘C using a MAX 80 cubic anvil high-pressure apparatus. The samples were mixed with Vaseline to ensure hydrostatic pressure-transmitting conditions, NaCl served as an internal standard for pressure calibration. By fitting a Birch-Murnaghan EOS to the data, the bulk modulus was determined as 116.0±1.3 GPa, (K ^′=4), V _T,0 =446.49 ³ exp[∫(0.33±0.05) × 10⁻⁴ + (0.65±0.85)×10⁻⁸ T dT], (K _T/T) _P  = −0.011± 0.004 GPa K⁻¹. The thermodynamic data obtained for Mg-sursassite are consistent with phase equilibrium data reported recently (Fockenberg 1998); the best agreement was obtained with Δ_f H ⁰ ₂₉₈ (Mg-sursassite) = −13901.33 kJ mol⁻¹, and S ⁰ ₂₉₈ (Mg-sursassite) = 614.61 J K⁻¹ mol⁻¹. Received: 21 September 2000 / Accepted: 26 February 2001     

Hindcasting community-level building damage for the 2011 Joplin EF5 tornado

Resiliency of communities prone to natural hazards can be enhanced through the use of risk-informed decision-making tools. These tools can provide community decision makers key information, thereby providing them the ability to consider an array of mitigation and/or recovery strategies. The Center for Risk-Based Community Resilience Planning, headquartered at Colorado State University in Fort Collins, Colorado, developed an Interdependent Networked Community Resilience (IN-CORE) computational environment. The purpose of developing this computational environment is to build a decision-support system, for professional risk planners and emergency responders, but even more focused on allowing researchers to explore community resilience science. The eventual goal was being to integrate a broad range of scientific, engineering and observational data to produce a detailed assessment of the potential impact of natural and man-made hazards for risk mitigation, planning and recovery purposes. The developing computational environment will be capable of simulating the effects from different natural hazards on the physical and socioeconomic sectors of a community, accounting for interdependencies between the sectors. However, in order to validate this computational tool, hindcasting of a real event was deemed necessary. Therefore, in this study, the community of Joplin, Missouri in the USA, which was hit by an EF-5 tornado on May 22, 2011, is modeled in the IN-CORE v1.0 computational environment. An explanation of the algorithm used within IN-CORE is also provided. This tornado was the costliest and deadliest single tornado in the USA in the last half century. Using IN-CORE, by uploading a detailed topological dataset of the community and the estimated tornado path combined with recently developed physics-based tornado fragilities, the damage caused by the tornado to all buildings in the city of Joplin was estimated. The results were compared with the damage reported from field studies following the event. This damage assessment was done using three hypothetical idealized tornado scenarios, and results show very good correlation with observed damage which will provide useful information to decision makers for community resilience planning.     

硝化微生物对五日生化需氧量测定的影响研究

通过对清洁水样、受污染水样、严重污染水样和全程序空白加与不加抑制剂的对比实验研究,分析硝化微生物对五日 生化需氧量（ＢＯＤ５）测定的影响情况,指出了所加入的硝化微生物抑制剂本身也在培养中被微生物分解而发生耗氧,给ＢＯＤ５的测定带来正系统误差,提出了清除其误差影响的办法。