ALBERT

Description: The possibility of predicting the droplet size distribution from the particle size distribution was investigated. For that purpose, suspensions of different types of materials were dried in a laboratory-scale spray drier. Drying of suspensions was performed with different sizes of two-fluid nozzles. Droplet size distribution was evaluated from the data obtained for spray drying of bismuth molybdate suspension. The method was validated experimentally with other tested materials. Investigated systems involve processes of drying, crystallization, and coating. The proposed methodology can be applied when nonagglomerated particles, spherical particles, or spherical agglomerates were obtained by spray drying. Spray drying is a unique drying process since formation of solid phase and drying occur simultaneously. Droplet size distribution produced by a two-fluid nozzle during spray drying of bismuth molybdate suspension was evaluated simply from the particle size distribution. The proposed methodology enables prediction of the particle size distribution obtained by spray drying.

Description: The influence of vibration parameters on the segregation phenomenon of a binary mixture in a vibration fluidized bed is investigated. Initially, the mixture composed of spherical balls with different densities but same diameter is in a perfect mixing state in the bed. The motion of particles is simulated based on the discrete element method. The effects of friction coefficient, vibration frequency, amplitudes, and gas velocity are analyzed. The coefficient of segregation to the degree of particle segregation is calculated for different operating conditions. The segregation degree in the vibration fluidized bed is found to be higher than that in the bed without vibration. The curve for the segregation degree exhibits a single peak value which represents the optimal segregation result. The impact of vibration on gas phase- and particle flow is not yet clarified due to the complex motion of particles in vibrated fluidized beds. Discrete particle simulation is used to investigate the segregation behavior of binary mixtures in a fluidized bed. The effect of vibration parameters and suitable operating conditions for segregation, particle distribution, and particle motion are evaluated.

Description: The effects of a turbulence-generating grid on fluid mixing and a passive chemical reaction are experimentally investigated in a liquid shear mixing layer under a nonpremixed condition. The grid is installed at three streamwise locations to find the optimal location to promote the chemical reaction. The results show that the grid generates disturbances at small scales that enhance fluid mixing and the chemical reaction. However, the turbulence intensity and mass diffusion in the mixing layers with the grid decrease rapidly and become even smaller than those in the mixing layer without the grid in a downstream region. Therefore, in the present study, the chemical production is maximized when the grid is installed at where the flow is turning to a developed mixing layer. Installation of a turbulence-generating grid is advantageous to promote fluid mixing and chemical reaction in a free shear flow in which the reactive fluids are introduced under a nonpremixed condition. Special attention is needed regarding the location of the grid to maximize the promotion effect since it could be better to install it in the downstream region rather than the upstream region.

Description: Bubble splitting in 2D gas-solid freely bubbling fluidized beds is experimentally investigated using digital image analysis. The quantitative results can be applied for the development of a new breakage model for bubbly fluidized beds, especially discrete bubble models. The variation of splitting frequency with bubble diameter, new resulting bubble volumes, positions, and also the assumptions of mass and momentum conservation for bubbles after breakage are studied in detail. Small bubbles are found to be more stable than large ones and nearly all mother bubbles split into two almost equally sized daughter bubbles. The momentum of gas bubbles in the vertical direction remains approximately constant after breakage, whereas that of bubbles in the horizontal direction changes with no clear trend. The effect of fluidizing gas velocity in breakage frequency is also examined. The behavior of gas bubbles plays a key role in heat- and mass-transfer operations in fluidized beds. Bubble splitting for Geldart B-type particles under varying conditions was investigated in a pseudo-2D gas-solid fluidized bed by digital image analysis. The quantitative results can facilitate the development of new breakage models for bubbly fluidized beds and are particularly relevant for discrete bubble modeling.

Description: For the application of microreactors in industrial processes, more scaling-up strategies are still required except of the original concept, the numbering-up. A more maneuverable and economic approach, combining both similarity-up and numbering-up, is introduced as an example for an innovative strategy. CFD simulation is also applied to assist analysis and optimization of fluid distribution. Based on this concept, named similarity-up + numbering-up + simulation, a pilot-plant microsieve dispersion minireactor used to proceed the reaction of cyclohexanecarboxylic acid and oleum is designed and tested experimentally. With the contribution of similarity-up, the treating capacity of the core unit is significantly increased. Ten parallel units are integrated to form a correspondingly enhanced capacity of the microreactor which exhibits low pressure drop, stable operating performance, and excellent main product selectivity. For industrial applications of microreactors, more flexible and economic scaling-up strategies are required. A scale-up approach for a microsieve dispersion reactor is proposed, combining similarity-up and numbering-up of the core unit with CFD simulation-based device structure optimization. Low fabrication cost, low pressure drop, and excellent main product selectivity can be achieved by this strategy.

Description: To study how an impacting plume modifies the mantle lithosphere, we analyzed the microstructures and crystal preferred orientations (CPO) of 29 peridotites and 37 pyroxenites that sample the mantle root of the Ontong Java Plateau (OJP) from 60 to 120 km depth. The peridotites show a strong compositional variability, but homogeneous coarse-granular to tabular microstructures, except for those equilibrated at the shallowest and deepest depths, which are porphyroclastic. All peridotites have clear olivine CPO, with dominant fiber-[010] patterns. Low intragranular misorientations and straight grain boundaries in olivine suggest that, above 100 km depth, annealing often followed deformation. Calculated density and P-wave velocities of the peridotites decrease weakly with depth. S-wave velocities decrease faster, resulting in increasing Vp/Vs ratio with depth. Calculated densities and seismic velocity profiles are consistent with those estimated for normal mantle compositions under a cold oceanic geotherm. Enrichment in pyroxenites may further increase seismic velocities. The calculated seismic properties cannot therefore explain the low S-waves velocities predicted by Rayleigh wave tomography and ScS data in the mantle beneath the OJP. Calculated P- and S-wave anisotropy is variable (2-12%). It is higher on average in the deeper section of the lithosphere. Because olivine has dominantly [010]-fiber CPO patterns, if foliations are horizontal, vertically propagating S-waves and Rayleigh waves will sample very weak anisotropy in the OJP mantle lithosphere. Moreover, if the orientation of the lineation changes with depth, the anisotropy-induced contrast in seismic properties might produce an intralithospheric reflector marking the stratification of the OJP mantle root.

Description: The quantification of heat and mass flow between deep reservoirs and the surface is important for understanding magmatic and hydrothermal systems. Here, we use high-resolution measurement of carbon dioxide flux (ϕCO 2 ) and heat flow at the surface to characterize the mass (CO 2 and steam) and heat released to the atmosphere from two magma-hydrothermal systems. Our soil gas and heat flow surveys at Rotokawa and White Island in the Taupō Volcanic Zone, New Zealand, include over 3,000 direct measurements of ϕCO 2 and soil temperature and 60 carbon isotopic values on soil gases. Carbon dioxide flux was separated into background and magmatic/hydrothermal populations based on the measured values and isotopic characterization. Total CO 2 emission rates (ΣCO 2 ) of 441 ± 84 t d -1 and 124 ± 18 t d -1 were calculated for Rotokawa (2.9 km 2 ) and for the crater floor at White Island (0.3 km 2 ), respectively. The total CO 2 emissions differ from previously published values by +386 t d -1 at Rotokawa and +25 t d -1 at White Island, demonstrating that earlier research underestimated emissions by 700% (Rotokawa) and 25% (White Island). These differences suggest that soil CO 2 emissions facilitate more robust estimates of the thermal energy and mass flux in geothermal systems than traditional approaches. Combining the magmatic/hydrothermal-sourced CO 2 emission (constrained using stable isotopes) with reservoir H 2 O:CO 2 mass ratios and the enthalpy of evaporation, the surface expression of thermal energy release for the Rotokawa hydrothermal system (226 MW t ) is 10 times greater than the White Island crater floor (22.5 MW t ).

Description: A new design of conjugated heat transfer in double-pass parallel-plate laminar countercurrent operations of power law fluids under wall isoflux was investigated experimentally and theoretically. The analytical solutions were obtained with a superposition model by introducing an eigenfunction expansion in terms of a power series for the homogeneous part and an asymptotic solution for the inhomogeneous part. The influence of the power law index on the average Nusselt numbers with the various design and operating parameters is also delineated. The theoretical predictions of the experimental results are represented graphically. The heat transfer performance was considerably improved when compared with a single-pass parallel-plate heat exchanger (without inserting a solid separator sheet). Suitable adjustments of the solid separator sheet position can effectively enhance the heat transfer efficiencies for such a recycling double-pass device, as compared with the efficiencies of single- and double-pass devices.

Description: To better constrain the mechanical behavior of sediments accreted to accretionary prism, we conducted triaxial mechanical tests on natural samples from the Miura-Boso paleo-accretionary prism (Japan) in drained conditions with confining pressures up to 200 MPa as well as post-experiments P-wave velocity (V p ) measurements. During experiments, deformation is principally non-coaxial and accommodated by two successive modes of deformation, both associated with strain-hardening and velocity-strengthening behavior: (1) compaction-assisted shearing, distributed in a several mm-wide shear zone and (2) faulting, localized within a few tens of µm-wide, dilatant fault zone. Deformation is also associated with (1) a decrease in Young's modulus all over the tests, (2) anomalously low V p in the deformed samples compared to their porosity and (3) an increase in sensitivity of V p to effective pressure. We interpret this evolution of the poroelastic properties of the material as reflecting the progressive breakage of intergrain cement and the formation of microcracks along with macroscopic deformation. When applied to natural conditions, these results suggest that the deformation style (localized vs distributed) of shallow (z 〈 a few km) sediments is mainly controlled by the variations in stress/strain rate during the seismic cycle and is therefore independent of the porosity of sediments. Finally, we show that the effect of strain, through cement breakage and microcracks formation, may lower V p for effective pressure up to 40 MPa. As a consequence, the low V p anomalies observed in Nankai accretionary prisms by seismic imaging between 2 and 4km depth [ Kitajima and Saffer , 2012] could reflect sediment deformation rather than porosity anomalies. This article is protected by copyright. All rights reserved.

Description: This study presents a new thermodynamic model for the calculation of phase relations during the melting of anhydrous spinel lherzolite at pressures of 1–2.5 GPa. The model is based on the total energy minimization algorithm for calculating phase equilibria within multicomponent systems and the thermodynamic configuration of Ueki and Iwamori [2013]. The model is based on a SiO 2 – Al 2 O 3 – FeO–Fe 3 O 4 –MgO–CaO system that includes silicate melt, olivine, clinopyroxene, orthopyroxene, and spinel as possible phases. The molar Gibbs free energy of the melt phase is modeled quasi-empirically, and the thermodynamic parameters for silicate melt end-member components are calibrated with a polybaric calibration database. The temperatures and pressures used in this newly compiled calibration dataset are 1230–1600 ∘ C and 0.9–3 GPa, corresponding to the stability range of spinel lherzolite. The modeling undertaken during this study reproduces the general features of experimentally determined melting phase relations of spinel lherzolite at 1–2.5 GPa, including the solidus temperature, the melt composition, the chemical reaction during melting and the degree of melting. This new thermodynamic modeling also reproduces phase relations of various bulk compositions from fertile to deplete spinel lherzolite and can be used in the modeling of polybaric mantle melting within various natural settings. Comparing the results derived from this new modeling with those produced using previous models indicates that the new approach outlined here, involving a combination of total energy minimization and the direct calibration of melt thermodynamic parameters at pressure and temperature conditions corresponding to mantle melting with a relatively simple melt thermodynamic equation, can accurately model polybaric melting phase relations. This article is protected by copyright. All rights reserved.

Description: In order to study emulsification phenomena, devices generating well-defined flow conditions are essential. Thus, emulsification of drop collectives under laminar shear flow is commonly performed in cylindrical Couette or Searle devices. In these devices, the flow conditions in the shear gap and in the volume underneath the rotor are often different, which can lead to inhomogeneous product properties and may complicate sample taking. Here, a novel cone-cone shear cell is presented to study emulsification processes. The flow inside the device is examined using numerical simulations. The numerical simulations indicate that simple shear flow is realized all over the sample volume in the cone-cone shear cell. The experimental results show that the drop breakup in the cone-cone shear cell is equivalent to the breakup under simple shear realized in the shear gap of a conventional device, i.e., the Searle device. Critical capillary numbers are calculated from the experimental data and show breakup behavior as predicted by single-drop experiments. Thus, the cone-cone shear cell proved to be suitable to study emulsification mechanisms in simple shear flow. Emulsion-based products are widely used in the food, chemical, and pharmaceutical industries. A novel cone-cone shear cell to study emulsification characteristics is described. The flow conditions inside the shear cell are validated via numerical simulations and experimental results.

Description: Hydrocracking of a bitumen-derived asphaltene over NiMo/ γ -Al 2 O 3 was investigated in a microbatch reactor at varying temperatures. The molar kinetics of asphaltene cracking reaction was examined by fitting the experimental data. Below a defined temperature, the molar reaction showed the first-order kinetic feature while at higher temperatures secondary reactions such as coke formation became significant, causing deviation of the reaction behavior from the proposed first-order kinetic model. Selectivity analysis proved that dominant products varied from gases to liquids to gases with increasing temperature, shifting the dominant reaction from C–S bonds cleavage to C–C bonds cleavage. Catalytic hydrocracking could be a proper choice for asphaltene upgrading but the reaction conditions still need to be optimized. Hydrocracking of a bitumen-derived asphaltene over a NiMo/ γ -Al 2 O 3 catalyst in a microbatch reactor at varying temperatures was analyzed. The molar kinetics of asphaltene cracking reaction was evaluated by fitting the experimental data.

Description: Two different types of metals (Cu and Ni) and the effect of CeO 2 addition to produce a CeO 2 -ZrO 2 co-supporter were investigated through the water-gas shift (WGS) reaction. It was found that the WGS activity could be enhanced with CeO 2 addition. At relatively high temperature, Ni-loaded catalysts exhibited higher CO conversion while Cu-loaded catalysts demonstrated better performance at low temperatures. The stability and yield of the CO 2 and H 2 products of the Cu catalysts were higher than those of the Ni catalysts. These results may be caused by an irreversible adsorption of CO on Ni and the reverse WGS reaction occurring on the Ni catalysts. In situ diffuse-reflection infrared Fourier transform spectroscopy data suggests that the WGS mechanism likely proceeded via formate species. The water-gas shift reaction (WGS), as an alternative way to produce H 2 and convert poisonous CO into CO 2 , was carried out using Cu and Ni loaded onto CeO 2 -ZrO 2 as catalysts. The Ni-loaded catalysts exhibited higher CO conversion at high temperature while the Cu-loaded catalysts performed better at low temperature. The WGS reaction was found to occur via the formation of formate species.

Description: Power ultrasound is applied for cooling crystallization to control and modify the particle size and crystal habit of an active pharmaceutical ingredient, phenacetin. Operating parameters including sonication intensity and duration, solution concentration, and cooling rate are studied and compared. With respect to mean particle size, the effect of sonication intensity is most significant. In addition, the crystal habit of recrystallized phenacetin is modified substantially and shows an elliptic shape. Recrystallized phenacetin also provides an enhanced dissolution rate compared with the original sample. These results prove that ultrasonic crystallization is an efficient tool for controlling the solid-state properties of an active pharmaceutical ingredient. Ultrasonic crystallization is a promising process for controlling the different stages of crystallization. Cooling crystallization applying power ultrasound is adopted for recrystallization of a nonsteroidal anti-inflammatory drug, phenacetin. The mean particle size can be managed by adjusting sonication intensity and duration. Phenacetin crystals with a regular crystal habit and an elliptic shape are obtained.

Description: In a variety of reactions in the chemical industry, eggshell catalysts with a thin active layer are applied; they are often crushed for laboratory testing. The destruction of the shell can be avoided by a special reactor design. The presented advanced TEMKIN reactor is a further development of the reactor system for testing eggshell catalysts on the laboratory scale published by Temkin and Kul'kova in 1969. It is suitable for kinetic studies and for the detailed investigation of deactivation processes, as shown on the example of selective hydrogenation of acetylene. The advanced TEMKIN reactor is well suitable for testing of uncrushed industrial eggshell catalysts because of its defined flow pattern and excellent mass and heat transport properties. Because of its simple and robust design, all technical requirements are fulfilled for a fast, competitive, and accurate optimization of prototypes as well as already established catalysts for industrial applications.

Description: A bench-scale submerged membrane bioreactor (SMBR) was employed to treat vegetable oil plant wastewater with complete sludge retention. Treatment performance and membrane fouling of the SMBR were investigated. The system stably removed high amounts of total organic carbon, oil, and ammonia from vegetable oil wastewater and reduced the chemical oxygen demand, demonstrating the great potential of the SMBR in removing pollutants. The membrane fouling layer was not only governed by deposition of organic substances composed of extracellular polymeric substances like proteins, polysaccharides etc., and oil substances but also by inorganic elements. Organic foulants coupled to inorganic precipitation enhanced the formation of a gel layer and triggered severe membrane fouling in the SMBR. Treatment and disposal of vegetable oil wastewaters (VOWs) represents one of the principal problems for vegetable oil producing countries. A bench-scale submerged membrane bioreactor was applied to treat VOWs with complete sludge retention. Treatment performance and membrane fouling were investigated. The experimental results demonstrated the great potential of this membrane bioreactor in removing pollutants.

Description: Adsorption processes are frequently applied to separate traces of hazardous and toxic substances from gas streams. Hence, knowledge of sorption characteristics of these substances on standard adsorbents is essential. Sorption of hexanal and acetaldehyde from a nitrogen gas stream in trace concentrations on activated carbon and ordered mesoporous carbon-based adsorbents (CMK) is studied. A magnetic suspension balance and an attached gaschromatograph-mass spectrometer were used to analyze the sorption process both gravimetrically and spectrometrically. Both types of adsorbents show a higher capacity for hexanal than acetaldehyde. The activated carbon exhibits considerable differences in regard to desorption of hexanal compared to the mesoporous CMK. Information on sorption characteristics of hazardous substances is essential to design separation processes. Adsorption and desorption of the toxic acetaldehyde and the intensely odorous hexanal on activated carbon and periodic mesoporous carbon were studied. Magnetic suspension balances were used to analyze the sorption processes. Both adsorbents exhibit a higher capacity for hexanal than acetaldehyde.

Description: High-solids biomass slurries exhibit non-Newtonian behavior with a yield stress and require high power input for mixing. The goals were to determine the effect of scale and geometry on power number P 0 , and estimate the power for mixing a pretreated biomass slurry in a 3.8 million L hydrolysis reactor of conventional design. A lab-scale computational fluid dynamics model was validated against experimental data and then scaled up. A pitched-blade turbine and A310 hydrofoil were tested for various geometric arrangements. Flow was transitional; laminar and turbulence models resulted in equivalent P 0 which increased with scale. The ratio of impeller diameter to tank diameter affected P 0 for both impellers, but impeller clearance to tank diameter affected P 0 only for the A310. At least 2 MW is required to operate at this scale. High-solids biomass slurries are characterized by non-Newtonian behavior with a yield stress and high power input demand for mixing. A computational fluid dynamics model was developed to predict power requirements of non-Newtonian lignocellulosic slurry in an industrial-scale hydrolysis reactor with conventional mixing impellers. The lab-scale model was validated against experimental data and then scaled up.

Description: The effect of NaCl added in different quantities on thermodynamic properties, granulometric characteristics, and structure of glycine in a crystallization process was investigated. Solubilities of α - and γ -polymorphs in the presence of varying amounts of NaCl were analyzed. In order to examine the impact of the additive on granulometric properties of glycine, crystal morphology was examined by observing crystals under a scanning electron microscope. Crystal size distribution was determined by sieve analysis. By X-ray diffraction analysis, the critical concentration of NaCl at which the structure of glycine changed, could be defined. The purity of obtained polymorphs was confirmed by Fourier transform infrared spectroscopy. Interactions between additives and crystallizing phase influence crystallization processes. Batch-cooling crystallization of glycine with different amounts of added NaCl is described, causing changes in solubility, metastable zone width, supersaturation, final mass of crystals, granulometric properties, and structure. Process conditions for a conversion of α- into a γ- glycine structure are defined.

Description: Cryogenic air separation as the most important part of an integrated gasification combined cycle is a widely used operation unit for producing large quantities of high-purity oxygen and nitrogen. However, cryogenic distillation requires a large amount of energy due to the work needed to compress the air feed. An improved heat-integrated air separation column (HIASC) is proposed. The requirements of high-purity separation in the industrial cryogenic air separation process are achieved. An optimization model of the heat transfer coefficient ( UA ), a key parameter in column structure design and operation, is presented. The optimized UA value is obtained within the accepted value range reported in the international open literature, which ensures the practicability of the improved HIASC. An improved heat-integrated air separation column is proposed. With the new heat-integrated and thermally coupled structure, the pressure of the high-pressure column and the energy consumption decrease significantly compared with the conventional air separation column. The mathematic model and parameter analysis are presented. An optimization model for the heat transfer coefficient is proposed.

Description: Functional mesoporous Mo–SiO 2 materials were synthesized by a one-pot and facile room-temperature procedure, and characterized by X-ray diffraction, TEM, Raman spectroscopy, FT-IR, diffuse reflectance spectra, and BET analysis. The experimental results demonstrated that the mesoporous materials presented a high dispersion of molybdenum species and excellent catalytic activity for the removal of dibenzothiophene (DBT) without organic solvents as extractants. The catalytic performance on different sulfur-containing compounds was also investigated in detail. After recycling for eight times, the removal of the oxidation desulfurization system could still reach high values. GC-MS analysis detected the oxidation product of DBT. A mechanism was proposed for the absorptive oxidation process of sulfur compounds. The removal of sulfur compounds from petroleum is of utmost importance for stringent fuel specifications and environment pollution. Functional mesoporous Mo–SiO 2 materials were synthesized by a facile procedure and were characterized by a high dispersion of molybdenum species and excellent catalytic activity for the removal of dibenzothiophene under mild conditions without organic solvents as extractants.

Description: The level set method is combined with the concentration transformation method to solve the interphase mass transfer process. However, the artificial diffusion generated in the mass transfer convection term across the interface is inevitable, especially when large shape deformation is encountered at high Reynolds numbers. A semi-Lagrangian advection scheme is introduced to overcome this disadvantage. The methyl isobutyl ketone (MIBK)-acetic acid-water system is adopted to study the unsteady mass transport process accompanied with the Marangoni effect of a single deformable drop ascending in the infinite continuous phase. The predicted overall mass transfer coefficients agree with experimental data very well. The configuration of Marangoni convection is revealed and its effect on the interphase mass transfer process is investigated. The solute-induced Marangoni effect on an ascending drop driven by buoyancy is numerically simulated based on the level set method. The semi-Lagrangian convection scheme is introduced to eliminate the artificial diffusion. Compared with literature data, the present algorithm with the semi-Lagrangian convection scheme significantly suppressed the numerical diffusion and achieved much better predictions.

Description: The surface properties of solvent-based (SB) and water-based (WB) coatings and their impact on fouling during convective heat transfer of CaSO 4 solutions were investigated. Experiments demonstrated that the SB coatings had generally better non-adhesive characteristics, especially at higher values of the electron donor component since the deposits could easily be washed away. For the SB coatings, a longer induction period compared to those of untreated surfaces was observed and a significant reduction of the fouling rate could be achieved. Further analysis of surfaces revealed that SB coatings enhanced the acid-base repulsive force and thus reduced the deposit/solid adhesion energy. For the WB coatings, the Liftshitz-van der Waals attractive force plays a decisive role in the adhesion process due to the higher apolar component of the surface energy. Recent technological advances have given impetus in altering surface properties to mitigate fouling of heat transfer surfaces. The attempted coatings in this study demonstrated that they can extend the induction period of the fouling processes of CaSO 4 deposits by four times. This was but mostly due to their higher electron donor component of the surface energy compared to stainless-steel substrate.

Description: Ultrasonic hot embossing of polymers is an alternative to reduce fabrication costs of microreactors. An ultrasonic welding machine is used to melt a stack of thermoplastic foils and adapting them to a short-time milled aluminum mold showing the inversed design of the desired microfluidic cavities. Two micromixers were fabricated this way providing a low degree of axial dispersion and pressure loss. Stability analysis is successfully performed for a wide temperature range and high pressure. Mixing of colored aqueous solutions and neutralization reactions are implemented to both systems for defined volume flow rates and optically investigated via microscope. Reaction progress is automatically determined with a MATLAB script by reference to the consequential color change of the neutralization reaction with a color indicator. Typical mixing characteristics are identified for both mixers. Ultrasonic hot embossing of chemically resistant polymers as a simple and cost-effective fabrication method of microstructures and an optical analysis tool for tracing the progress of chemical reactions are introduced and evaluated. The simplicity of the fabrication method itself and good similarities of produced polymer micromixers with conventional ones made of other materials are pointed out.

Description: The existing screening and characterization systems for biocatalysts operate in batch mode, which could make catalyst selection and process development inaccurate when continuous operation mode is required in industry. A significant improvement of an innovative screening system based on miniaturized multiple membrane reactors formerly presented by the author is outlined, which enables continuous feeding of substrates and continuous removal of products. Although the presented screening system was originally designed for homogeneous enzymatic reactions, it can be used without further modifications for continuous catalysis with polymer-bound chemical catalysts or for quasi-homogeneous systems like reverse micelles. Currently available screening and characterization systems for biocatalysis are not sufficiently suitable for process description and scale-up of results to pilot- or full-scale reactors often operated in continuous mode. Hydrolysis of N -acetyl- L -methio-nine served as model reaction for an innovative continuous characterization system, implementing a precise dosing system.

Description: The synthesis of n -butyl levulinate, one of the most important biodiesel additives, by catalytic esterification of biomass-derived levulinic acid (LA) with n -butanol over modified H-ZSM-5 (micro/meso-HZ-5) in a closed-batch system is reported for the first time. The optimization of the reaction conditions such as the reactant molar ratio, the catalyst loading, the reaction time and the temperature was performed in view to maximize the yield of n -butyl levulinate. Micro/meso-HZ-5 was found to be the most efficient catalyst, with 98 % yield of n -butyl levulinate and a reusability for six cycles, which is higher than reported in the literature. A possible catalytic mechanism for the esterification reaction is also proposed. A second-order pseudo-homogeneous model with R 2  〉 0.97 confirmed that the esterification reaction is performed in the kinetic regime due to the high activation energy of 23.84 kJ mol −1 . The modified zeolite catalyst H-ZSM-5 (micro/meso-HZ-5) was used as heterogeneous acid catalyst in the esterification of renewable levulinic acid with n -butanol to produce n -butyl levulinate in a closed system. Micro/meso-HZ-5 turned out to be an efficient catalyst with 98 % yield of n -butyl levulinate and high reusability.

Description: Knowledge on the behavior of Mg isotopes during metamorphic dehydration is the prerequisite for applying Mg isotopes as tracers for crustal recycling. Here, we report Mg isotopic compositions of metapelites from the Onawa contact aureole, Maine. Except one sample, all metapelites across the aureole, from the wall-rock regional metamorphic rocks to the partially melted rocks adjacent to the pluton, have similar Mg isotopic compositions (δ 26 Mg = -0.09 to +0.12‰). This observation indicates limited Mg isotope fractionation during metamorphic dehydration and fluid-rock interaction, due to the low Mg concentration in fluids relative to rocks. Our results suggest that Mg isotopic compositions of metapelites can record those of their protoliths and, hence, recycled clastic sedimentary materials may preserve their low-temperature Mg isotopic signatures through subduction zones. Therefore, Mg isotopes may serve as new tracers for crustal recycling, for example, tracing components experienced weathering cycles within granite sources.

Description: Magnetic anomaly identifications underpin plate tectonic reconstructions and form the primary dataset from which age of the oceanic lithosphere and seafloor spreading regimes in the ocean basins can be determined. Although these identifications are an invaluable resource, their usefulness to the wider scientific community has been limited due to the lack of a central community infrastructure to organize, host and update these interpretations. We have developed an open-source, community-driven online infrastructure as a repository for quality-checked magnetic anomaly identifications from all ocean basins. We provide a global sample dataset that comprises 96,733 individually picked magnetic anomaly identifications organized by ocean basin and publication reference, and provide accompanying Hellinger-format files, where available. Our infrastructure is designed to facilitate research in plate tectonic reconstructions or research that relies on an assessment of plate reconstructions, for both experts and non-experts alike. To further enhance the existing repository and strengthen its value, we encourage others in the community to contribute to this effort.

Description: We present an efficient method for high-volume heavy mineral separation from clay-rich rocks using an ultrasonic probe. The ultrasonic clay separator (UCS) is an easily constructed device that allows for the recovery of high-density minerals, as small as 10 microns, with a minimum of sample preparation. Heavy mineral recovery from clay-rich material with the UCS yields a greater number of small (〈100 micron) grains and approximately double the amount of material from that of gravity settling and decanting. Despite development with heavy mineral recovery in mind, the UCS should suitable for recovering small grain size geologic materials from flocculating clay-rich material.

Description: In the detachment mode of slow seafloor spreading, convex-upward detachment faults take up a high proportion of the plate separation velocity exposing gabbro and serpentinized peridotite on the seafloor. Large, long-lived hydrothermal systems such as TAG are situated off-axis and may be controlled by fluid flow up a detachment fault, with the source of magmatic heat being as deep as 7 kmbsf. The consequences of such deep circulation for the evolution of fluid temperature and salinity have not previously been investigated. Microthermometry on fluid inclusions trapped in diabase, gabbro and trondjhemite, recovered at the Atlantis Massif Oceanic Core Complex (30° N, mid-Atlantic Ridge), reveals evidence for magmatic exsolution, phase separation, and mixing between hydrothermal fluids and previously phase separated fluids. Four types of fluid inclusions were identified, ranging in salinity from 1.4 wt.% NaCl to 35 wt.% NaCl, although the most common inclusions have salinities close to seawater (3.4 wt.% NaCl). Homogenization temperatures range from 160 to 〉400 °C, with the highest temperatures in hypersaline inclusions trapped in trondjhemite and the lowest temperatures in low salinity inclusions trapped in quartz veins. The fluid history of the Atlantis Massif is interpreted in the context of published thermochronometric data from the Massif, and a comparison with the inferred circulation pattern beneath the TAG hydrothermal field, to better constrain the pressure temperature conditions of trapping and when in the history of exhumation of the rocks sampled by IODP Hole U1309D fluids have been trapped.

Description: Robot in Laboratory. Copyright: Max Tactic – Fotolia.com.

Description: We study the elastic wave speed structure of the crust and the uppermost mantle in western Tibet using P and S-wave arrival times from regional earthquakes recorded by a temporary seismic network. We relocate the earthquakes, and subsequently invert travel time residuals for 3D distributions of wave speed. Resolution tests with a variety of input structures are used to verify the reliability of our results. The crust beneath western Tibet has low P-wave speed (5.9 - 6.3 km/s) throughout its nearly 80 km thickness, with lower values in this range concentrated within the Lhasa block. Beneath the Himalaya wave speeds are higher. Southern and western limits of the slow material beneath the Tibetan Plateau correlate with the Karakoram fault, and dip beneath the plateau at ~40° angle. We find no evidence of a sub-horizontal low velocity zone in the crust. In the uppermost mantle we find a long and narrow region of fast (up to 8.4 km/s) P-wave speed extending from the Karakoram fault in NE direction, and crossing the Bangong-Nujiang suture. In a north-south cross-section, the distribution of relatively fast P-wave speed suggests a ramp-flat geometry consistent with India underthrusting the Tibetan Plateau at least as far as 32.5°N. A plausible interpretation of the upper mantle fast feature is the formation of eclogite from the mafic lower-crustal material of India after it is underthrust beneath Tibet. Notably, in western Tibet this process only takes place in a narrow region.

Description: We have employed shear wave splitting techniques to image anisotropy beneath the D'Entrecasteaux Islands, in southeastern Papua New Guinea. Our results provide a detailed picture of the extending continent that lies immediately ahead of a propagating mid-ocean ridge tip; we image the transition from continental to oceanic extension. A dense shear wave splitting dataset from a 2010-11 passive-source seismic deployment is analyzed using single- and multi-channel methods. Splitting delay times of 1-1.5 s are observed and fast axes of anisotropy trending N-S, parallel to rifting direction, predominate the results. This trend is linked to lattice-preferred orientation of olivine, primarily in the shallow convecting mantle, driven by up to 200 km of N-S continental extension ahead of the westward-propagating Woodlark Rift. This pattern differs from several other continental rifts that evince rift-strike-parallel fast axes and is evident despite the complex recent tectonic history. We contend that across most of this rift, the unusually high rate and magnitude of extension has been sufficient to produce a regime change to a mid-ocean-ridge-like mantle fabric. Stations in the south of our array show more complex splitting that might be related to melt or to complex inherited structure at the edge of the extended region.

Description: From April 2010 through February 2011, CO 2 flux surveys were performed on Lake Rotomahana, New Zealand. The area has been hydrothermally active with fumaroles and sublacustrine hydrothermal activity before and since the eruption of Mt Tarawera in 1886. The total CO 2 emission from the lake calculated by sequential Gaussian simulation is 549 ± 72 t day -1 . Two different mechanisms of degassing, diffusion through the water-air interface and bubbling, are distinguished using a graphical statistical approach. The carbon dioxide budget calculated for the lake confirms that the main source of CO 2 to the atmosphere is by diffusion covering 94.5 % of the lake area (mean CO 2 flux 25 g m -2 day -1 ) and to a lesser extent, bubbling (mean CO 2 flux 1297 g m -2 day -1 ). Mapping of the CO 2 flux over the entire lake, including over lakefloor vents detected during the survey, correlates with eruption craters formed during the 1886 eruption. These surveys also follow regional tectonic patterns present in the southeastern sector of Lake Rotomahana suggesting a deep magmatic source (~ 10 km) for CO 2 and different pathways for the gas to escape to the surface. The values of δ 13 C CO2 (-2.88 and -2.39 ‰) confirm the magmatic origin of CO 2 .

Description: Regional-scale geologic structures characteristic of mantle lithosphere within cratons found in continent interiors are interpreted using geo-registered diverse data sets from the Slave craton of northwest Canada. We developed and applied a new method for mapping seismic discontinuities in three dimensions using multi-year observations at sparse, individual broadband receivers. New, fully 3-D conductivity models used all available magnetotelluric data. Discontinuity surfaces and conductivity models were geo-registered with previously published P-wave and surface wave velocity models to confirm first-order structures such as a mid-lithosphere discontinuity. Our 3-D model to 400 km depth was calibrated by ‘drill hole’ observations derived from xenolith suites extracted from kimberlites. A number of new structural discontinuities emerge from direct comparison of co-registered data sets and models. Importantly we distinguish primary mantle layers from secondary features related to younger metasomatism. Sub-horizontal Slave craton layers with tapered, wedge-shaped margins indicate construction of the craton core at 2.7 Ga by underthrusting and flat stacking of lithosphere. Mapping of conductivity and metasomatism in 3-D, the latter inferred via mineral recrystallization and resetting of isotopic ages in xenoliths, indicates overprinting of the primary layered structures. The observed distribution of relatively conductive mantle at 100–200 km depths is consistent with pervasive metasomatism; vertical ‘chimneys’ reaching to crustal depths in locations where kimberlites erupted or where Au mineralization is known.

Description: Understanding the nature of the crust has long been a goal for seismologists when imaging the Earth. This is particularly true in volcanic regions where imaging melt storage and migration can have important implications for the size and nature of an eruption. Receiver functions and the H- κ stacking (H κ ) technique are often used to constrain crustal thickness (H) and the ratio of P- to S-wave velocities ( κ ). In this paper I show that it is essential to consider anisotropy when performing H κ . I show that in a medium with horizontally transverse isotropy a strong variation in κ with back azimuth is present which characterises the anisotropic medium. In a vertically transverse isotropic medium no variation in κ with back azimuth is observed, but κ is increased across all back azimuths. Thus, estimates of κ are more difficult to relate to composition than previously thought. I extend these models to melt induced anisotropy and show that similar patterns are observed, but with more significant variations and increases in κ . Based on these observations I develop a new anisotropic H- κ stacking technique which inverts H κ data for melt fraction, aspect ratio and orientation of melt inclusions. I apply this to data for the Afar Depression and show that melt is stored in interconnected stacked sills in the lower crust, which likely supply the recent volcanic eruptions and dike intrusions. This new technique can be applied to any anisotropic medium where it can provide constraints on the average crustal anisotropy.

Description: A Fortran 90 program to visualize data on the Yin-Yang grid system is developed. The purpose of this study is to provide simulation researchers with a source code as a starting point of their own custom-made visualization tools. A basic but sufficiently diverse set of visualization methods are implemented using a Fortran 90 binding for OpenGL for scalar and vector fields defined or simulated on the Yin-Yang grid.

Description: Twelve submarine mud volcanoes (MV) in the Kumano forearc basin within the Nankai Trough subduction zone were investigated for hydrocarbon origins and fluid dynamics. Gas hydrates diagnostic for methane concentrations exceeding solubilities were recovered from MVs 2, 4, 5, and 10. Molecular ratios (C 1 /C 2 〈250) and stable carbon isotopic compositions (δ 13 C-CH 4 〉−40‰ V-PDB) indicate that hydrate-bound hydrocarbons (HCs) at MVs 2, 4, and 10 are derived from thermal cracking of organic matter. Considering thermal gradients at the nearby IODP Sites C0009 and C0002, the likely formation depth of such HCs ranges between 2,300 and 4,300 m below seafloor (mbsf). With respect to basin sediment thickness and the minimum distance to the top of the plate boundary thrust we propose that the majority of HCs fueling the MVs is derived from sediments of the Cretaceous to Tertiary Shimanto belt below Plio-/Pleistocene to recent basin sediments. With respect to sizes and appearances hydrates are suggested to be relicts of higher MV activity in the past, although the sporadic presence of vesicomyid clams at MV 2 showed that fluid migration is sufficient to nourish chemosynthesis-based organisms in places. Distributions of dissolved methane at MVs 3, 4, 5, and 8 pointed at fluid supply through one or few MV conduits and effective methane oxidation in the immediate subsurface. The aged nature of the hydrates suggests that the major portion of methane immediately below the top of the methane-containing sediment interval is fueled by current hydrate dissolution rather than active migration from greater depth.

Description: Polyethersulfone (PES) was blended with poly( D,L -lactide) (PDLLA) to prepare asymmetric membranes using the phase inversion method. The effects of the blend ratios and poly(ethylene glycol) (PEG) as additive on the membrane structure, properties, and performance were investigated. The membranes were characterized by contact angle determination, scanning electron microscopy, porosity measurement, thermogravimetric analysis, degradation tests in compost, and dynamic tests for pure water flux and bakery product wastewater treatment. PES and PEG slightly reduced the membrane contact angle. Increasing the PDLLA concentration in the blend membranes enhanced the membrane degradation in compost and also the membrane porosity. The permeate flux of the membranes was improved, but the rejection of pollution indices did not change noticeably. Porous membranes have been widely applied in the fields of dialysis, clarification, and purification. The composition of membranes prepared by blending polyethersulfone with poly( D,L -lactide) (PDLLA) affected their characteristics. Increases in the concentrations of PDLLA and the additive poly(ethylene glycol) led to more porous structures, causing higher fluxes.

Description: 40 Ar/ 39 Ar geochronology depends critically on well calibrated standards, often traceable to first-principles K-Ar age calibrations using bulb-tracer systems. Tracer systems also provide precise standards for noble-gas studies and interlaboratory calibration. The exponential expression long-used for calculating isotope tracer concentrations in K-Ar age dating and calibration of 40 Ar/ 39 Ar age standards may provide a close approximation of those values, but is not correct. Appropriate equations are derived that accurately describe the depletion of tracer reservoirs and concentrations of sequential tracers. The true form of the expression is a power law, not exponential, and a similar expression was presented by Miiller (2006, J. Res. Natl. Inst. Stand. Technol., 111 (5), 335–360). Evaluation of the expressions demonstrates that systematic error introduced through use of the exponential approximation may be substantial where reservoir volumes are small and resulting depletion constants are large. Traditional use of large reservoir to tracer volumes and the resulting small depletion constants have kept errors well less than experimental uncertainties in most previous K-Ar and calibration studies. Use of the proper expression, however, permits use of volumes appropriate to the problems addressed.

Description: Natural hydrate-bearing sediment (HBS) predominantly exists in non-cementing habit, and its limited availability for use in laboratory studies demands a time-effective and repeatable laboratory process for forming representative samples with natural accumulation habit. This study reports on a three-step laboratory process for forming non-cementing methane hydrate in sandy sediments: (1) initial HBS formation under excess-gas conditions; (2) slow saline water (5wt % CaCl 2 ) injection under strictly controlled PT conditions; and (3) a temperature warming/cooling cycle. Changes in compressional wave velocity ( V p ) of sediment, as well as pressure-temperature (P-T) condition, were monitored throughout the tests. The evolution of V p , in good agreement with rock physics model calculations, suggested that the transition from cementing hydrate into non-cementing hydrate occurs during saline injection as well as temperature warming/cooling cycle. The proposed process appeared to be an efficient and consistent substitute for the existing methods, to form non-cementing hydrate habit in sandy sediments.

Description: Great earthquakes anticipated on the Cascadia subduction fault can potentially rupture beyond the geodetically and thermally inferred locked zone to the depths of episodic tremor and slip (ETS) or to the even deeper forearc mantle corner (FMC). To evaluate these extreme rupture limits, we map the FMC from southern Vancouver Island to central Oregon by combining published seismic velocity structures with a model of the Juan de Fuca plate. These data indicate that the FMC is somewhat shallower beneath Vancouver Island (36–38 km) and Oregon (35–40 km) and deeper beneath Washington (41–43 km). The updip edge of tremor follows the same general pattern, overlying a slightly shallower Juan de Fuca plate beneath Vancouver Island and Oregon (˜30 km) and a deeper plate beneath Washington (˜35 km). Similar to the Nankai subduction zone, the best constrained FMC depths correlate with the center of the tremor band suggesting that ETS is controlled by conditions near the FMC rather than directly by temperature or pressure. Unlike Nankai, a gap as wide as 70 km exists between the downdip limit of the inferred locked zone and the FMC. This gap also encompasses a ˜50 km wide gap between the inferred locked zones and the updip limit of tremor. The separation of these features offers a natural laboratory for determining the key controls on downdip rupture limits.

Description: The separation efficiency of a pilot-scale zigzag apparatus is investigated numerically using computational fluid dynamics simulations and discrete particle modeling in a coupled manner. The effects of various process variables, like particle size and air flow velocity, and of turbulence models were analyzed. The resulting changes concerning the process performance expressed by separation function and sharpness are discussed. Moreover, the residence time distribution was found to differ for fine and coarse particle discharges. Small particles are easily carried away by the fluid and respond immediately to almost every change in flow velocity. Therefore, they are affected by vortices, which increase their residence times compared to bigger particles. Zigzag air classifiers are superior to simple sieves for the separation of particles and are used in many industrial processes. The separation efficiency of a pilot-scale zigzag apparatus is studied using combined computational fluid dynamics simulations and discrete particle modeling. The process performance is discussed with respect to the chosen modeling approach and the operating conditions.

Description: During eruptions onto low slopes, basaltic Pahoehoe lava can form thin lobes that progressively coalesce and inflate to many times their original thickness, due to a steady injection of magma beneath brittle and viscoelastic layers of cooled lava that develop sufficient strength to retain the flow. Inflated lava flows forming tumuli and pressure ridges have been reported in different kinds of environments, such as at contemporary subaerial Hawaiian-type volcanoes in Hawaii, La Réunion and Iceland, in continental environments (states of Oregon, Idaho, Washington), and in the deep sea at Juan de Fuca Ridge, the Galapagos spreading center, and at the East Pacific Rise (this study). These lava have all undergone inflation processes, yet they display highly contrasting morphologies that correlate with their depositional environment, the most striking difference being the presence of water. Lava that have inflated in subaerial environments display inflation structures with morphologies that significantly differ from subaqueous lava emplaced in the deep sea, lakes, and rivers. Their height is 2 to 3 times smaller and their length being 10 to 15 times shorter. Based on heat diffusion equation, we demonstrate that more efficient cooling of a lava flow in water leads to the rapid development of thicker (by 25%) cooled layer at the flow surface, which has greater yield strength to counteract its internal hydrostatic pressure than in subaerial environments, thus limiting lava breakouts to form new lobes, hence promoting inflation. Buoyancy also increases the ability of a lava to inflate by 60%. Together, these differences can account for the observed variations in the thickness and extent of subaerial and subaqueous inflated lava flows.

Description: I analyze the seismic tomography around the Japanese Islands to elucidate the present slab morphology. A simple conversion from the high speed to the temperature anomaly is done based on the recent study of the conversion coefficient from the velocity to the thermal anomaly and on the study of the relation between the seismicity and the temperature in the slab. I find recognizable amount of cold temperature anomalies under the subducting slab. This suggests a rather continuous slab throughout the mantle consistent with the results of many recent numerical models. However, there still is a gap in the slab or diluted slab under the transition zone. To understand this, I construct a simple half-kinematic model of subduction zone in which a Byerlee's type yield stress and the depth independent yield stress are assumed. Taking into account the geologic history around the Japanese Islands, I find that the slab morphology similar to the tomographic image is obtained when the yield stress is O(100 MPa). The present study shows that the detailed studies of seismic tomography and the tectonic history of the surveyed area can provide the constraints on the slab dynamics.

Description: As the supercontinent Rodinia was assembling ca. 1.1 billion years ago, there was extensive magmatism on at least five Proterozoic continents including the development of the North American Midcontinent Rift. New paleomagnetic data from 84 lava flows of the Osler Volcanic Group of the Midcontinent Rift reveal that there was a significant and progressive decrease in inclination between the initiation of extrusive volcanism in the region (ca. 1110 Ma) and ca. 1105 ± 2 Ma (the “early stage” of rift development). Paleomagnetic poles can be calculated for the lower portion of the reversed Osler Volcanic Group (40.9°N, 218.6 °E, A 95 =4.8°, N=30) and the upper portion of the reversed Osler Volcanic Group (42.5°N, 201.6 °E, A 95 =3.7°, N=59; this pole can be assigned the age of ca. 1105 ± 2 Ma). This result is a positive test of the hypothesis that there was significant plate motion during the early stage of rift development. In addition to being a time of widespread volcanism on Laurentia and other continents, this interval of the late Mesoproterozoic was characterized by rapid paleogeographic change.

Description: The relationship between magnetic hysteresis parameters and the degree of oxidation of ultrafine magnetite particles is examined by both experimental measurements (distributed particle assemblage with median grain size of ~80 nm and standard deviation 0.43) and micromagnetic simulations (single particles from 40 nm to 140 nm). Experimental results show that both coercivity (B c ) and the ratio of saturation remanence to saturation magnetization (M rs /M s ) increase slowly, as the oxidation parameter z increases from 0 to ~0.9. Thereafter both parameters decrease sharply as magnetite becomes completely oxidized to maghemite. Numerical simulations of hysteresis loop and microstructure using a micromagnetic model with a core-shell geometry (a stoichiometric core surrounded by an oxidized shell) show three categories of behavior for magnetic grains during oxidation. Firstly, the coercivity of SD particles decreases as oxidation proceeds, but their remanence magnetization remains in a uniform state. Secondly, for PSD sized particles near the critical SD boundary (80 nm to 100 nm), the initial vortex domain structure changes to a SD as oxidation occurs and returns to a vortex state upon complete maghemitization, resulting in an initial rise and then fall of B c and M rs . Finally, larger PSD grains remain a vortex state throughout the maghemitization, with less variations of B c and M rs . The predicted magnetic properties exhibit good agreement with experimental observations and suggest that the domain arrangement is likely to be dominated by a core-shell structure with strong exchange coupling at their interface. Overall, the partially oxidized magnetite in SD-PSD range can reliably record palaeomagnetic signals.

Description: We report 3 He/ 4 He for 150 mid-ocean ridge basalt (MORB) glasses from the Southeast Indian Ridge (SEIR). Between 81°-101°E 3 He/ 4 He varies from 7.5 to 10.2 R A , encompassing more than half the MORB range away from ocean island hotspots. Abrupt transitions are present and in one case the full range occurs over ~10 km. Melting of lithologically heterogeneous mantle containing a few percent garnet pyroxenite or eclogite leads to lower 3 He/ 4 He, while 3 He/ 4 He above ~9 R A likely indicates melting of pyroxenite-free or eclogite-free mantle. Patterns in the length scales of variability represent a description of helium isotopic texture. We utilize four complementary methods of spectral analysis to evaluate this texture, including Periodogram, Redfit, Multi-Taper Method and Continuous Wavelet Transform. Long-wavelength lobes with prominent power at 1000 km and 500 km are present in all treatments, similar to hotspot-type spectra in Atlantic periodograms. The densely sampled region of the SEIR considered separately shows significant power at ~100 km and ~30-40 km, the latter scale resembling heterogeneity in the bimodal distribution of Hf and Pb isotopes in the same sample suite. Wavelet transform coherence reveals that 3 He/ 4 He varies in-phase with axial depth along the SEIR at ~1000 km length scale, suggesting a coupling between melt production, 3 He/ 4 He and regional variations in mantle temperature. Collectively, our results show that the length scales of MORB 3 He/ 4 He variability are dominantly controlled by folding and stretching of heterogeneities during regional (~1000 km) and mesoscale (~100 km) mantle flow, and by sampling during the partial melting process (~30 km).

Description: Reconstructing convective flow in the Earth's mantle is a crucial issue for a diversity of disciplines, from seismology to sedimentology. The common and fundamental limitation of these reconstructions based on geodynamic modelling is the unknown initial conditions. Because of the chaotic nature of convection in the Earth's mantle, errors in initial conditions grow exponentially with time and limit forecasting and hindcasting abilities. In this work we estimate for the first time the limit of predictability of Earth's mantle convection. Following the twin experiment method, we compute the Lyapunov time (i.e. e-folding time) for state-of-the art 3D spherical convection models, varying rheology and Rayleigh number. Our most Earth-like and optimistic solution gives a Lyapunov time of 136±13 My. Rough estimates of the uncertainties in best guessed initial conditions are around 5%, leading to a limit of predictability for mantle convection of 95 My. Our results suggest that error growth could produce unrealistic convective structures over timescales shorter than that of Pangea dispersal.

Description: In order to observe the impact of different water compositions on sludge dewaterability, assessments of floc sizes using a particle size analyzer and of sludge dewaterability based on the capillary suction time (CST) test were carried out. Synthetic raw water had small floc sizes, and synthetic domestic wastewater had both larger median floc sizes and a better correlation between sludge dewaterability and median floc sizes. The floc size distribution results showed that synthetic raw water is associated with a narrow particle size distribution. In comparison, synthetic domestic wastewater produced a wider distribution. However, the CST values were similar for both waters. Compared to synthetic wastewater, natural wastewater had the largest distribution with generally larger particle sizes. In order to observe the impact of different water compositions on sludge dewaterability, assessments of floc sizes and sludge dewaterability tests were carried out. The particle distribution results show that synthetic raw water is associated with a very narrow range of particles. In comparison, synthetic domestic wastewater produced a larger distribution. The capillary suction times were similar.

Description: The direct-ignition technology of an entrained-flow coal-water slurry gasifier with hot-oxygen burner (HOB) is presented. Experimental tests were carried out using diesel oil and coal-water slurry in a bench-scale entrained-flow opposed multi-burner (OMB) gasifier. Using a CCD camera equipped with high-temperature endoscope, flame images inside the gasifier were recorded and subsequently processed. The results show that the HOB diesel flame is more stable than the normal two-channel burner flame typically used. Entrained-flow coal-water slurry gasifiers can start up using the HOB directly without a higher preheated wall temperature. An HOB can potentially save gasifier preheating time and operation costs and enables a wide range of future applications. Entrained-flow gasification offers one of the cleanest ways to obtain energy from coal. The direct-ignition technology of an entrained-flow coal-water slurry gasifier with a new type of hot-oxygen burner (HOB) was extensively studied to prove the feasibility of the gasifier startup with this setup. The HOB permits to effectively decrease the gasifier preheating time and the system operation costs.

Description: Different approaches were analyzed to combine the tuneable micropore structure of carbide-derived carbons with a foam-like secondary porosity. The resulting structured catalyst supports were characterized in detail and applied in the model reaction of ethene hydrogenation. Preparation methods studied were dip-coating using polytetrafluoroethylene as binder on cellular metal structures, a chemical vapor deposition coating of the metal structures with thin carbide layers and subsequent conversion to carbide-derived carbon, and the partial or full conversion of carbide foams to carbon/carbide composites. For the binder method, optimal parameters for stable slurry preparation as well as for calcination of the slurry were obtained. It could further be demonstrated that the conversion of carbide foams into carbon/carbide composites leads to an appreciation between decreasing mechanical strength and increasing specific surface area. Structured catalysts are advantageous to conventional fixed-bed systems. Carbide-derived carbons with tuneable microporous structure were combined with a foamlike catalyst structure. The three preparation methods studied resulted in highly active catalysts. Optimal conditions for the easy-to-apply dip-coating method to stabilize the slurry for successful coating were determined and evaluated.

Description: An opposed multi-burner (OMB) entrained-flow gasifier with coal water slurry feeding is developed by the East China University of Science and Technology. A 3D model is employed to numerically simulate the gas flow field, motion of char particles, and distributions of temperature and gaseous components in an OMB gasifier and in a conceptual two-stage gasifier modified from the OMB gasifier (TS-OMB gasifier). Results show that the TS-OMB gasifier produces higher concentration and productivity of the effective gases (CO+H 2 ) with a slightly higher carbon conversion than the OMB gasifier. The reasons for the differences between these two types of gasifier are discussed by means of numerical simulation. This information is valuable for guiding the design of an advanced OMB gasifier. With an increasing demand for syngas, entrained-flow gasifiers for coal conversion are installed at the fastest pace due to advantages such as low pollutant emission. Simulations of the gas component distribution, amongst other key factors, in an opposed multi-burner (OMB) gasifier and modified two-stage OMB gasifier were compared. The results are valuable for future design of an advanced OMB gasifier.

Description: Low-magnitude earthquake swarms (M L ≤ 2.8), consisting of up to 47 events of similar waveforms, have been observed repeatedly in the central Southern Alps, a rapidly uplifting orogen bounded by the transpressive Alpine Fault in the South Island of New Zealand. We compare nine background swarms recorded between November 2008 and April 2010 with five delayed-triggered swarms that occurred after the M W 7.8 Dusky Sound and the M W 7.1 Darfield (Canterbury) earthquakes. The two types of swarms are similar in terms of the magnitudes, depths, focal mechanisms, and inter-event times of the constituent microearthquakes, and appear to both involve the rupture of steeply-dipping faults in highly fractured crust in a 10 km × 12 km area in the centre of the SAMBA network. The delayed-triggered swarms occurred at similar epicentral distances (c.4.5× the rupture length of the mainshocks) to the Dusky Sound and Darfield earthquakes, commenced shortly after the passage of the surface waves, continued for ~5 and ~2 days, respectively, and were followed by a ≥2 day-long quiescent period, which may suggest clock-advanced of faults in their failure-cycle. Triggering thresholds of ≥0.01 MPa proposed elsewhere are similar to the dynamic stress changes computed for the Southern Alps (≥0.09 MPa). However, as 98% of the locatable triggered events occurred several hours after the surface waves had passed, the dynamic stress changes associated with the surface waves themselves are unlikely to have triggered the earthquakes directly. Instead, we suggest that the locations and delays of the triggered swarms are more consistent with triggering by pore pressure diffusion.

Description: The isotropic and anisotropic P -wave velocity structure of the upper oceanic crust on the Endeavour Segment of the Juan de Fuca Ridge is studied using refracted travel time data collected by an active-source, three-dimensional tomography experiment. The isotropic velocity structure is characterized by low crustal velocities in the overlapping spreading centers (OSCs) at the segment ends. These low velocities are indicative of pervasive tectonic fracturing and persist off-axis, recording the history of ridge propagation. Near the segment center, velocities within the upper 1 km show ridge-parallel bands with low velocities on the outer flanks of topographic highs. These features are consistent with localized thickening of the volcanic extrusive layer from eruptions extending outside of the axial valley that flow down the fault-tilted blocks that form the abyssal hill topography. On-axis velocities are generally relatively high beneath the hydrothermal vent fields likely due to the infilling of porosity by mineral precipitation. Lower velocities are observed beneath the most vigorous vent fields in a seismically active region above the axial magma chamber and may reflect increased fracturing and higher temperatures. Seismic anisotropy is high on-axis but decreases substantially off-axis over 5-10 km (0.2-0.4 Ma). This decrease coincides with an increase in seismic velocities resolved at depths ≥1 km and is attributed to the infilling of cracks by mineral precipitation associated with near-axis hydrothermal circulation. The orientation of the fast-axis of anisotropy is ridge-parallel near the segment center but curves near the segment ends reflecting the tectonic fabric within the OSCs.

Description: Factory. Copyright: Dmitry Lavrenyuk – Fotolia.com .

Description: Chemical and isotopic signatures for black shales serve as potential proxies for reconstruction of paleoenvironmental conditions. Here we bring Rock-Eval, major and trace element and Re-Os isotopic data together to examine the environmental record at the Cambrian-Ordovician Global Stratotype Section and Point ( GSSP ) at Green Point in western Newfoundland, Canada. The Green Point shales are oil mature and contain Type-II organic material of marine origin. A Re-Os isochron for the shales provides the first radiometric age for shale deposition at the GSSP at 484 ± 16 Ma, with an initial 187 Os/ 188 Os ratio of 0.74 ± 0.05 (Model 3 age; MSWD = 21; n =13; σ uncertainties). Factor analysis of the geochemical dataset shows association of most trace elements with total organic carbon (TOC) and S contents, ensuring an authigenic origin for most elements and hence, their validity for evaluating the paleo-redox state. Relatively high enrichment factors for redox-sensitive elements ( e.g . Re, U and Mo) compared to average shale, but comparatively low enrichment compared to modern Black Sea sediments, suggest deposition in anoxic, but not euxinic waters. Comparison of Lower Ordovician shale geochemistry datasets at a global scale leads us to suggest that anoxic conditions and warm oceanic regimes were restricted to the margins of Laurentia and Baltica whereas depositional basins with colder waters ( e.g . Avalonia and Gondwana) were less reducing. These outcomes underscore the important role of paleogeography in regulating oceanic conditions and marine life.

Description: The outcome of paleointensity experiments largely depends on the rock-magnetic properties of the samples. To assess the relation between volcanic emplacement processes and rock-magnetic properties we sampled a vertical transect in a ˜6 m thick inflated lava flow at Hawaii, emplaced in ˜588 AD. Its rock-magnetic properties vary as function of distance from the flow top; the observations can be correlated to the typical cooling rate profile for such a flow. The top and to a lesser extent the bottom parts of the flow cooled faster and reveal a composition of ˜TM60 in which the magnetic remanence is carried by fine-grained titanomagnetites, relatively rich in titanium, with associated low Curie and unblocking temperatures. The titanomagnetite in the slower cooled central part of the flow is unmixed into the magnetite and ülvospinel end-members as evidenced by scanning electron microscope observation. The remanence is carried by coarse-grained magnetite lamella (˜TM0) with high Curie and unblocking temperatures. The calibrated pseudo-Thellier results that can be accepted yield an average paleointensity of 44.1 ± 2.4 μT. This is in good agreement with the paleointensity results obtained using the thermal IZZI-Thellier technique (41.6 ± 7.4 μT) and a recently proposed record for Hawaii. We therefore suggest that the chance of obtaining a reliable paleointensity from a particular cooling unit can be increased by sampling lavas at multiple levels at different distances from the top of the flow combined with careful preliminary testing of the rock-magnetic properties.

Description: Volcanic glasses recovered from four guyots during drilling along the Louisville Seamount Trail, southwest Pacific, have been analyzed for major, trace and volatile elements (H 2 O, CO 2 , S, Cl, F), and oxygen isotopes. Compared to other oceanic island settings they are geochemically homogeneous, providing no evidence of the tholeiitic stage that characterizes Hawai'i. The degrees and depth of partial melting remained constant over 1 – 3 Ma represented by the drill holes, and along-chain over several million years. The only exception is Hadar Guyot with compositions that suggest small degree preferential melting of an enriched source, possibly because it erupted on the oldest and thickest lithosphere. Incompatible element enriched glass from late-stage volcaniclastics imply lower degrees of melting as the volcanoes moved off the melting anomaly. Volcaniclastic glasses from throughout the igneous basement are degassed suggesting generation during shallow submarine eruptions (〈20 mbsl) or as subaerial flows entered the sea. Drill depths may no longer reflect relative age due to post-quench downslope movement. Higher volatile contents in late-stage volcaniclastics indicate submarine eruptions at 118 – 258 mbsl and subsidence of the edifices below sea level by the time they erupted, or generation in flank eruptions. Glass from intrusion margins suggest emplacement ~100 m below the surface. The required uplift to achieve these paleo-quench depths and the subsequent subsidence to reach their current depths exceed that expected for normal oceanic lithosphere, consistent with the Louisville melting anomaly being 〈100 °C hotter than normal asthenosphere at 50 – 70 Ma when the guyots were erupted.

Description: Understanding the controls for magma ascent and storage depth is important for volcanic hazard assessment. Regional differences in the depth of magma storage between volcanic arcs suggest that the settings of subduction zones and of overriding plates influence how magma ascends through the crust. Here we use a compilation of data for 70 volcanoes in 15 volcanic regions to better understand the geodynamic controls on magma storage. We describe the subduction system, which consists of the subducting slab, the mantle wedge and the upper plate with 12 parameters encompassing the kinematics of the subduction, the structure and geometry of the slab, the timing of the subduction, the thermal structure of the slab, the upper-plate crustal structure, its stress regimes, and its thermal structure. We find that the magma reservoir depths correlate with the upper-plate crustal structure and with the stress regimes. Shallow reservoirs (〈5 km depths) are 52% more common in young Tertiary crust than in old Precambrian crust and 42 % more common in thin crust (〉25 km) than in thick crust (〉 45 km). Similarly, shallow magma reservoirs are 33 to 69% more common in extensional and strike slip stress regimes that in compressional regimes. This illustrates the effect of buoyancy for magma ascent as well as the importance of stress and preexisting structures.

Description: We present a shear wave splitting (SWS) database for the western and central United States as part of a lasting effort to build a uniform SWS database for the entire North America. The SWS measurements were obtained by minimizing the energy on the transverse component of the PKS, SKKS, and SKS phases. Each of the individual measurements was visually checked to ensure quality. This version of the database contains 16105 pairs of splitting parameters. The data used to generate the parameters were recorded by 1774 digital broadband seismic stations over the period of 1989-2012, and represented all the available data from both permanent and portable seismic networks archived at the Incorporated Research Institutions for Seismology Data Management Center in the area of 26.00 ∘ N to 50.00 ∘ N and 125.00 ∘ W to 90.00 ∘ W. About 10000 pairs of the measurements were from the 1092 USArray Transportable Array stations. The results show that approximately 2/3 of the fast orientations are within 30 ∘ from the absolute plate motion (APM) direction of the North American plate, and most of the largest departures with the APM are located along the eastern boundary of the western US orogenic zone and in the central Great Basins. The splitting times observed in the western US are larger than, and those in the central US are comparable with the global average of 1.0 s. The uniform database has an unprecedented spatial coverage and can be used for various investigations of the structure and dynamics of the Earth.

Description: Steel pipe line. Copyright: supakitmod – Fotolia.com.

Description: Light olefin and paraffin are commonly separated by energy-intensive cryogenic distillation. Membrane/distillation hybrid systems constitute an economical alternative separation process. Different configurations of this hybrid system are studied for olefin-paraffin separation with emphasis on C 3 separation. An approach based on the McCabe-Thiele method is applied to analyze different process configurations. A facilitated transport membrane is considered as membrane type. Both new column design and augmentation of an existing distillation column by a membrane module are considered. Numerical examples are considered for the separation of propane from propylene through different hybridization shapes with facilitated transport membranes. The energy requirement can be halved using hybrid systems. Membrane/distillation hybrid systems represent an economical alternative separation process compared to the commonly applied energy-intensive cryogenic distillation for separation of light olefin and paraffin. Different process configurations of such a hybrid system are evaluated. Under optimum conditions the energy requirement could be halved.

Description: Shelves from volcanic ocean islands result from the competition between two main processes, wave erosion that forms and enlarges them and volcanic progradation that reduces their dimension. In places where erosion dominates over volcanism, shelf width can be used as a proxy for the relative age of the subaerial volcanic edifices and reconstruction of their extents prior to erosion can be achieved. In this study new multibeam bathymetry and high-resolution seismic reflection profiles are exploited to characterize the morphology of the insular shelves adjacent to each volcanic edifice of Terceira Island in order to improve the understanding of its evolution. Subaerial morphological and geological/stratigraphic data were also used to establish the connection between the onshore and offshore evolution. Shelf width contiguous to each main volcanic edifice is consistent with the known subaerial geological history of the island; most of the older edifices have wider shelves than younger ones. The shelf edge proved to be a very useful indicator in revealing the original extent of each volcanic edifice in plan-view. Its depth was also used to reconstruct vertical movements, showing that older edifices like Serra do Cume–Ribeirinha, Guilherme Moniz and Pico Alto have subsided whilst more recent ones have not. The morphology of the shelf (namely the absence/presence of fresh lava flow morphologies and several types of erosional, depositional and tectonic features) integrated with the analysis of the coastline morphology allowed us to better constrain previous geological interpretations of the island evolution.

Description: Both silicate melts and aqueous fluids are thought to play critical roles in the chemical differentiation of the Earth's crust and mantle. Yet their relative effects are poorly constrained. We have addressed this issue by measuring partition coefficients for 50 trace and minor elements in experimentally produced aqueous fluids, co-existing basanite melts and peridotite minerals. The experiments were conducted at 1.0-4.0 GPa and 950-1200 °C in single capsules containing (either 40 or 50 wt. %) H 2 O and trace element enriched basanite glass. This allowed run products to be easily identified and analysed by a combination of electron microprobe and LAM-ICP-MS. Fluid and melt compositions were re-constructed from mass-balances and published solubility data for H 2 O in silicate melts. Relative to the basanite melt, the solutes from H 2 O-fluids are enriched in SiO 2 , alkalis, Ba and Pb, but depleted in FeO, MgO, CaO and REE. With increasing pressure the mutual solubility of fluids and melts increases rapidly with complete miscibility between H 2 O and basanitic melts occurring between 3.0 and 4.0 GPa at 1100 °C. Although LREE are favoured over HREE in the fluid phase, they are less soluble than the HFSE (Nb, Ta, Zr, Hf and Ti). Thus the relative depletions of HFSE that are characteristic of arc magmas must be due to a residual phase that concentrates HFSE (e.g. rutile). Otherwise H 2 O-fluids have the capacity to impart many of the geochemical characteristics that distinguish some rocks and melts from the deep mantle lithosphere (e.g. MARID and lamproites).

Description: We describe the aftershocks of a Mw 7.4 intraplate normal-faulting earthquake that occurred 150 km east Ogasawara (Bonin) Islands, Japan, on December 21, 2010. It occurred beneath the outer trench-slope of the Izu-Ogasawara trench, where the Pacific plate subducts beneath the Philippine Sea plate. Aftershock observations using ocean bottom seismographs (OBS) began soon after the earthquake and multi-channel seismic reflection surveys were conducted across the aftershock area. Aftershocks were distributed in a NW-SE belt 140 km long, oblique to the N-S trench axis. They formed three subparallel lineations along a fracture zone in the Pacific plate. The OBS observations combined with data from stations on Chichi-jima and Haha-jima Islands revealed a migration of the aftershock activity. The first hour, which likely outlines the mainshock rupture, was limited to an 80-km-long area in the central part of the subsequent aftershock area. The first hour activity occurred mainly around, and appears to have been influenced by, nearby large seamounts and oceanic plateau, such as the Ogasawara Plateau and the Uyeda Ridge. Over the following days, the aftershocks expanded beyond or into these seamounts and plateau. The aftershock distribution and migration suggest that crustal heterogeneities related to a fracture zone and large seamounts and oceanic plateau in the incoming Pacific plate affected the rupture of the mainshock. Such pre-existing structures may influence intraplate normal-faulting earthquakes in other regions of plate flexure prior to subduction.

Description: Variations in seismic velocities are essential in developing a better understanding of continental plate tectonics. Fortunately, the USArray has provided an excellent set of regional phases from the recent M5.6 Oklahoma earthquake (2011/11/06, Table 1) that can be used for such studies. Its strike-slip mechanism produced an extraordinary set of tangential recordings extending to the northern edge of the USArray. The crossover of the crustal slow S to the faster S n phase is well observed. S m S has a critical distance of around 2° and its first multiple, SmS 2 , reaches critical angle near a distance of about 4°, and so on, until S m S n merges with the stronger crustal Love waves. These waveforms are modeled in the period band of 2—100 s by assuming a simple three-layer crust and a two-layer mantle, which allows a grid-search approach. Our results favor a 15-km-thick low-velocity zone (LVZ) in the lower crust with an average shear velocity of less than 3.6 km/s. The short-period Lg waves (S-waves, at periods of 0.5—2 s) travel with velocities near 3.5 km/s and decay with distance faster than high-frequency S n (〉5.0 Hz) which travels at a velocity of 4.6 km/s and persists to large distances. Although these short-period waveforms are not modeled, their amplitude and travel times can be explained by adding a small velocity jump just below the Moho with essentially no attenuation. P n is equally strong but is complicated by the interference produced by the depth phase sP, but well modeled. The P-velocities appear normal with no definitive LVZ. While these observations of S n and P n are common beneath most cratons, the lower crustal LVZ appears to be anomalous and maybe indicative of hydrous processes, possibly caused by the descending Farallon slab.

Description: We have performed reaction experiments between 1, 4 and 5 wt.% CO 2 -bearing MORB-eclogite (recycled oceanic crust)–derived low degree andesitic partial melt and fertile peridotite at 1375 °C, 3 GPa for infiltrating melt fractions of 25% and 33% by weight. We observe that the reacted melts are alkalic with degree of alkalinity or Si-undersaturation increasing with increasing CO 2 content in reacting melt. Consequently, an andesite evolves through basanite to nephelinite owing to greater drawdown of SiO 2 from melt and enhanced precipitation of orthopyroxene in residue. We have developed an empirical model to predict reacted melt composition as a function of reacting andesite fraction and source CO 2 concentration. Using our model, we have quantified the mutual proportions of equilibrated melt from andesite-peridotite (+ CO 2 ) hybridization and subsequent peridotite (± CO 2 )-derived melt required to produce the major element composition of various ocean island basalts. Our model can thus be applied to characterize the source of ocean islands from primary alkalic lava composition. Accordingly, we determined that average HIMU source requires 20 wt.% of MORB-eclogite-derived melt relative to peridotite containing 0.4 wt.% CO 2 and subsequent contribution of 40% of volatile-free peridotite partial melt. We demonstrate that mantle hybridization by eclogite melt-peridotite (± CO 2 ) reaction in the system can produce high MgO (〉15 wt.%) basaltic melts at mantle potential temperature ( T P ) of 1350 °C. Therefore, currently used thermometers to estimate T P using MgO content of primary alkalic melts need to be revised, with corrections for melt-rock reaction in a heterogeneous mantle as well as presence of CO 2 .

Description: We obtain scaling relationships for nonlinear attenuation of S-waves and Love waves within sedimentary basins to assist numerical modeling. These relationships constrain the past peak ground velocity (PGV) of strong 3-4 s Love waves from San Andreas events within Greater Los Angeles, as well as the maximum PGV of future waves that can propagate without strong nonlinear attenuation. During each event, the shaking episode cracks the stiff, shallow rock. Over multiple events this repeated damage in the upper few hundred meters leads to self-organization of the shear modulus. Dynamic strain is PGV divided by phase velocity and dynamic stress is strain times the shear modulus. The frictional yield stress is proportional to depth times the effective coefficient of friction. At the eventual quasi-steady self-organized state, the shear modulus increases linearly with depth allowing inference of past typical PGV where rock over the damaged depth range barely reaches frictional failure. Still greater future PGV would cause frictional failure throughout the damaged zone, nonlinearly attenuating the wave. Assuming self-organization has taken place, estimated maximum past PGV within Greater Los Angeles basins is 0.4 to 2.6 m s -1 . The upper part of this range includes regions of accumulating sediments with low S-wave velocity that may have not yet compacted, rather than having been damaged by strong shaking. Published numerical models indicate that strong Love waves from the San Andreas Fault pass through Whittier Narrows. Within this corridor, deep drawdown of the water table from its currently shallow and pre-industrial levels would nearly double PGV of Love waves reaching Downtown Los Angeles.

Description: Paleomagnetic studies of dyke swarms from the Variscan belt of Europe can be used to reconstruct internal post-orogenic rotations within the fold belt. Here, we present paleomagnetic data from 13 late Variscan dykes from Sardinia ranging in age from 298 ± 5Ma to 270 ± 10Ma. The dykes can be grouped on the basis of their different directions in strike in a northern, a central-eastern and a south-eastern province. Paleomagnetic component directions have been obtained using thermal and alternating field demagnetization techniques, which give reproducible results. The paleomagnetic mean directions differ significantly between northern Sardinia and south-eastern and central-eastern Sardinia, the latter two regions yielding statistically similar paleomagnetic mean directions. These results indicate that Sardinia fragmented into two, arguably three, crustal blocks after emplacement of the dykes, which experienced differential relative rotations, as is also indicated by the differences in overall strike directions. The determination of timing, sense and magnitude of these rotations has major implications for the reconstruction of the geodynamic evolution of the region in post-Carboniferous times. We argue that the observed block rotations occurred during the Permian as the result of post-Variscan intra-Pangea mobility possibly related to the transformation of an Early Permian Pangea B to a Late Permian Pangea A.

Description: High-resolution magnetic surveys acquired near the seafloor show that active basalt-hosted hydrothermal sites are associated with zones of lower magnetization. This observation may reflect the thermal demagnetization of a hot hydrothermal zone, the alteration of basalt affected by hydrothermal circulation, and/or the presence of thick, non-magnetic hydrothermal deposits. In order to discriminate among these inferences, we acquired vector magnetic data 50 m above inactive hydrothermal site Krasnov using the Remotely-Operated Vehicle (ROV) Victor . This deep hydrothermal site, located 7 km east of the Mid-Atlantic Ridge (MAR) axis at 16°38'N, is dissected by major normal faults and shows no evidence of recent hydrothermal activity. It is therefore a perfect target for investigating the magnetic signature of an inactive basalt-hosted hydrothermal site. Krasnov exhibits a strong negative magnetic anomaly, which implies that the lower magnetization observed at basalt-hosted hydrothermal sites is not a transient effect associated to hydrothermal activity, but remains after activity ceases. Thermal demagnetization plays only a secondary role, if any, in the observed magnetic low. Forward models suggest that both the non-magnetic hydrothermal deposits and an altered zone of demagnetized basalt are required to account for the observed magnetic low. The permanence of this magnetic signature makes it a useful tool to explore mid-ocean ridges and detect inactive hydrothermal sites.

Description: To reduce environmental impact of cement production, granulated blast furnace slag (GBFS) can be used as a cement clinker substitution. Its reactivity of can be increased by adequate fine grinding. The impact of different conventional laboratory-scaled mills (ball mill, vertical mill, and roller press) on the material properties was researched. Granulometrical, structural, and calorimetrical investigations were done. It could be demonstrated that at the same fineness the grinding unit does not significantly influence the cement performance like hydration heat release and compressive strength. On the other hand, particle properties like particle size distribution, particle shape, and thus workability characteristics of composite cements have been changed. The replacement of ordinary produced cement by ground granulated blast furnace slag (GGBFS) in the cement production reduces negative impacts on the environment. By adequate fine grinding the reactivity of GGBFS as a cement linker substitution could be enhanced. The influence of grinding devices on the reactivity of GGBFS is investigated and evaluated.

Description: The impact of polydispersity index (PDI) values and doses of two sodium polyacrylates on grinding limits and particle size distributions of highly concentrated limestone suspensions was studied. The results indicated that viscosity and agglomerate particle size, and thus the apparent grinding limit, depended on the sodium polyacrylate dose as well as PDI value of sodium polyacrylate. The higher the sodium polyacrylate dose, the lower the viscosity and the smaller the apparent grinding limit were. The smallest primary particle size, the smallest apparent grinding limit, the narrowest agglomerate particle size distribution, and the lowest viscosity curve were obtained with sodium polyacrylate having a low PDI. Ultrafine grinding of limestone in stirred media mills is an attractive method for nano-CaCO 3 production. Effects of polydispersity index and doses of two sodium polyacrylates on the grinding limits of limestone suspensions were studied. Sodium polyacrylate with a low polydispersity index turned out to be an effective grinding aid for limestone.

Description: A method was sought that allows for coordinating the particle grinding time and the particle size in a closed milling circuit. This can be achieved by placing the input of the return flow from an end classifier at an intermediate position of the tube mill length. A simple model to estimate the efficiency of the approach is proposed. It is shown that such an optimal position exists and depends on the classifier efficiency. One of the key problems in improving the efficiency of grinding is how to match the particle size and the necessary grinding time. A model for optimizing the position of the circulating load input in a closed milling circuit with a tube mill is proposed. It is shown that such an optimum does exist and can yield a considerable gain in the circuit capacity.

Description: Phenomena related to sieving of non-spherical particles are investigated numerically in two batch apparatuses and on a horizontally aligned continuous sieve by particle-based simulation approaches in the framework of the discrete element method. The feed material is approximated by complex-shaped particles composed of clustered spheres. Comparisons are made with regard to the passage through the screen as well as the segregation and transportation on the screen. Results for passage are compared to data from literature, where simulations with spherical particles were performed of a laboratory-scale sieve operated with non-spherical quarry rock particles. Additionally, variations in screen inclination are investigated. Experimental results are matched by the simulations. A distinctive influence of particle shape on flow rates and residence times is identified. Despite many modeling advances, phenomenological models still lack the ability to represent dynamic processes within the unit operation sieving. Here, discrete element method simulations of complex-shaped particles on two batch apparatuses and a continuously operated sieve are performed. Phenomena related to sieving of non-spherical particles are investigated numerically.

Description: The process and end-use behavior of ground material not only depends on the particle size or specific surface but is also influenced by the particle shape. Particle shaping can be done in a stirred media mill if the stress intensity is not enough to break the particle, so mainly abrasion and chipping are carried out. Low-stress intensity milling is presented in a dry stirred media mill to reveal the particle base rounding and surface roughness reduction. The main parameters of the product-related stress model are connected to the descriptive parameters of particle shaping. Batch grinding of limestone particles with narrow size distribution was carried out with different milling parameters. The product-related stress model can be used for the description of particle shaping. The rounded shape and smooth surface of particles is necessary for many processes. A stirred media mill was used in dry mode to produce rounded or smooth surface particles in a size range of a few hundred microns without significant size reduction. An evaluation method was created to show the effect of the milling parameters on the particle shaping in relation to the product-related stress model.

Description: The influence of several process parameters like milling time, ball-to-beaker volume ratio, diameter of milling balls, and rotation frequency on the Knoevenagel condensation of vanillin and barbituric acid in planetary ball mills was investigated. These parameters determine the amount of energy provided for the reaction. Additionally, numerical simulations were carried out to describe the stress conditions in detail and to compute the drive power and energy transfer which cannot be measured directly. The mill and experimental parameters were modeled by the discrete element method with adequate coefficients of friction and restitution required to describe the powder behavior in the system. The coefficients were determined by correlation of experiments and simulations. Mechanochemical synthesis may offer green solutions to organic synthesis. Using the Knoevenagel reaction under solvent-free conditions in a planetary ball mill, the results are correlated with discrete element method simulations to prove the dependency of the reaction yield on stress conditions. Smaller balls were more time and energy efficient due to higher power values achieved by high stress frequencies.

Description: The aim of this work is to clarify the complex interactions and various influencing parameters regarding the material behavior of deep-frozen bulk solids. Additionally, a better evaluation of the material behavior in practical applications needs to be ensured. As material samples, hard coal, iron ore, and sand were selected, and cube-shaped samples saturated with water were deep-frozen for defined periods of time. Subsequently, the influences of the residence time in the freezer and of the particle size on the material behavior were analyzed by carrying out uniaxial compression tests. An economically and technically efficient method is needed to overcome the problems associated with frozen coal. Hard coal, iron ore, and sand samples saturated with water were deep-frozen for defined periods of time. Uniaxial compression tests were carried out to analyze the influence of the particle size and the residence time in the freezer on the material behavior.

Description: A general overview for the process development and manufacturing of engineered drug particles by size reduction techniques is provided. Drug compound and drug product characteristics are reviewed, which may need an engineered drug particle size. Drug particle attributes are introduced which are affected by size reduction techniques and potentially require additional downstream processing effort. The development of drug particle size specifications is described, including adequate size control. A brief overview is given on dry- and wet-milling technologies currently applied in drug development and manufacturing, including selected application examples. Finally, the processing of highly active drug compounds is introduced with respect to equipment design, worker protection, cleaning and waste management to minimize worker exposure and environmental impact. A brief overview is given on drug compound and drug product characteristics impacted by drug particle size. Size reduction techniques applied after chemical synthesis and isolation processing are introduced for the engineering of drug particle size. The repercussions for the processing of highly active drug compounds are overviewed with regard to worker exposure and environmental impact.

Description: The production of nanosuspensions via stirred-media milling has proved to be an effective method to overcome bioavailability challenges of poorly water-soluble active pharmaceutical ingredients (APIs). The fine-grinding of the APIs cinnarizine and fenofibrate was investigated. Important process parameters were varied and the influence on product quality was studied. Different challenges were identified prior to and during milling: Foaming inside the milling equipment and agglomeration of fenofibrate occurred, and a long-term grinding experiment for cinnarizine revealed an increase in particle size, caused by ripening of the drug crystals during milling. Thus, the stability against ripening during the process is a newly identified challenge for the fine-grinding of APIs. The influence of process parameters on product quality for the milling of the active pharmaceutical ingredients fenofibrate and cinnarizine was investigated. Besides the well-known challenge regarding stabilization of the newly formed (nano)particles, a further challenge occurred: the ripening of the cinnarizine crystals during or shortly after the milling process.

Description: The interest in finer, dry products has led to the development of more efficient jet milling processes. The first part of the paper describes the thermodynamic basic principles for generation and application of steam, and compressed gases. Practical experience has shown that in the aspired fineness range stabilization during grinding provides an enormous potential for improvement. Some selected examples demonstrate that the energy requirement can be reduced by a factor of more than two by suitable choice of stabilizers. Application of single-stage, uncooled low-pressure compressors for jet milling offers an economical alternative to double-stage, cooled compressors for fine grinding. Stabilization during grinding provides an enormous potential for improvement. Selected examples demonstrate that the energy requirement can be reduced by a factor of 〉 2 with suitable stabilizers.

Description: Wet grinding processes, especially in terms of nanoparticle production, are extremely energy intensive, and for hard and abrasive product materials, high grinding media wear is produced. In order to minimize energy consumption, the choice of the process parameters is crucial. The decision on the process parameters often depends on experience or a certain number of laboratory- or pilot-scale experiments. Here, an enhanced stress energy model is used, which enables the prediction of optimum process parameters for inorganic materials in wet stirred media milling based on results for a different grinding material. The use of this model to select the process parameters is also valid with regard to grinding media wear: The grinding media wear reaches minimum values if the optimum parameters pertaining to the minimum specific energy are chosen based on this enhanced stress energy model, especially if soft products are ground. An enhanced stress energy model is used for the prediction of optimum process parameters for inorganic materials in wet stirred media milling based on results for a different grinding material. Optimization of the process parameters leads to minimum wear values for a certain product fineness, especially for materials that are softer than the grinding media material.

Description: Wheat bran is a vegetal fibrous material rich in different chemicals (e.g. arabinoxylan) that can be used as food ingredient. To increase the extractability of these compounds, production of small fiber particles and therefore milling for long periods of time have been proposed. Different laboratory- and pilot-scale technologies for fine and ultrafine grinding of wheat bran were evaluated in this publication. Various milling tools were applied both under wet and dry conditions. Generally better results were obtained when grinding the wheat bran under dry condition. Optimum results were achieved by a combination of ball milling followed by treatment of the powder with a jet air mill. Electron microscopic evaluation confirmed the sub-micrometer size of most particles and the presence of agglomerates. Wheat bran fibers are important in the food industry. Smaller fiber particle sizes could increase the extractability of its components. Therefore, different milling conditions were tested and optimal results were obtained when dry wheat bran was milled with a ball mill followed by a jet mill. Generally, finer particle size distributions could be achieved when dry milling conditions were applied.

Description: The ferrimagnetic mineral greigite (cubic Fe 3 S 4 ) is well known as an intracellular biomineralization product in magnetic bacteria and as a widely occurring authigenic mineral in anoxic sediments. Due to the lack of suitable single-crystal specimens, the magnetic anisotropy parameters of greigite have remained poorly constrained, to the point where not even the easy axis of magnetization is known. Here we report on an effort to determine the anisotropy parameters on the basis of ferromagnetic resonance (FMR) powder spectroscopy on hydrothermally synthesized, chemically pure greigite microcrystals dispersed in a nonmagnetic matrix. In terms of easy axis orientations, the FMR data are consistent with 〈111〉 or 〈100〉, or less likely, a more general 〈uv0〉 type. With a g factor of 2.09, the anisotropy field is about 90 mT and in some samples may reach 125 mT, compared to 30 mT for cubic magnetite. This confirms the dominating role of cubic anisotropy on the magnetic properties of greigite, which we show to be responsible for large SIRM/k values. K 1 is in the range -15 … - 23 J/m 3 (〈111〉) or +10 … +15 kJ/m 3 (〈100〉), yielding upper limits of 44 or 34 nm for the superparamagnetic grain size, respectively.

Description: We present multiple lines of evidence for years- to decade-long changes in the location and character of volcanic activity at West Mata seamount in the NE Lau Basin over a 16 year period, and a hiatus in summit eruptions from early 2011 through at least September 2012. Boninite lava and pyroclasts were observed erupting from its summit in 2009 and hydroacoustic data from a succession of hydrophones moored nearby show near-continuous eruptive activity from January 2009 to early 2011. Successive differencing of seven multibeam bathymetric surveys of the volcano made in the 1996-2012 period reveal a pattern of extended constructional volcanism on the summit and northwest flank punctuated by eruptions along the volcano's WSW rift zone (WSWRZ). Away from the summit, the volumetrically largest eruption during the observational period occurred between May 2010 and November 2011 at ~2920 m depth near the base of the WSWRZ. The (nearly) equally long ENE rift zone did not experience any volcanic activity during the 1996-2012 period. The cessation of summit volcanism recorded on the moored hydrophone was accompanied or followed by the formation of a small summit crater and a landslide on the eastern flank. Water column sensors, analysis of gas samples in the overlying hydrothermal plume and dives with a remotely operated vehicle in September 2012 confirmed that the summit eruption had ceased. Based on the historical eruption rates calculated using the bathymetric differencing technique, the volcano could be as young as several thousand years.

Description: A new mathematical model of the collision probability between bubbles and non-spherical particles is proposed. In this model it is assumed that the characteristic size of the particle is much smaller than the bubble radius; the particle density is close to the density of the flotation medium and the particle moves along a streamline flowing around the floating bubble (so-called inertialess flotation). So, the stochastic orientation of the particle with respect to the bubble surface was considered. On the basis of this model, the analytical expressions of the collision probability for rod-like and disk-like particles in the Stokes and Levich hydrodynamic regimes were obtained. The obtained results were compared with previous theories and experimental data. For a particle suspended in an aqueous medium to be captured, the rising bubble must first collide with this particle. A new mathematical model of the collision probability between bubbles and non-spherical particles is proposed, considering the stochastic orientation of the particles with respect to the bubbles surface. The results are compared with previous theories and experimental data.

Description: Understanding carbon cycling in continental margin settings is critical for constraining the global carbon cycle. Here we apply a multiproxy geochemical approach to evaluate regional carbon cycle dynamics in six New Zealand fjords. Using carbon and nitrogen concentrations and isotopes, lipid biomarkers, and redox-sensitive element concentrations, we show that the New Zealand fjords have carbon-rich surface sediments in basins that promote long-term storage (i.e., semi-restricted basins with sediment accumulation rates of up to 3 mm yr -1 ). Using δ 13 C distributions to develop a mixing model, we find that organic carbon in fjord sediments is well-mixed from marine and terrestrial sources in down-fjord gradients. This is driven by high regional precipitation rates of 〉6 m yr -1 , which promote carbon accumulation in fjord basins through terrestrial runoff. In addition, we have identified at least two euxinic sub-basins, based on uranium, molybdenum, iron, and cadmium enrichment, that contain 〉7% organic carbon. Because the strength and position of the Southern Hemisphere westerly winds control precipitation and fjord circulation, carbon delivery and storage in the region are intimately linked to westerly wind variability. We estimate that the fjord region (759 km 2 ) may be exporting up to 1.4 x 10 7 kgC yr -1 , outpacing other types of continental margins in rates of carbon burial by up to three orders of magnitude.

Description: Evidence from sediment core records and model studies suggest that increased nutrient supply played a key role in the initiation of the Cenomanian-Turonian oceanic anoxic event 2 (OAE2; 94 Ma). However, the relative roles of nitrogen (N) and phosphorus (P) availability in controlling primary productivity during the event are not fully understood. Here, we expand an existing multi-box model of the coupled cycles of P, carbon and oxygen in the proto-North Atlantic by adding the marine N cycle. With the updated version of the model, we test the hypothesis that enhanced availability of P can fuel N 2 -fixation, increase primary productivity and drive large parts of the proto-North Atlantic to anoxia during OAE2. In a sensitivity analysis, we demonstrate that N dynamics in the proto-North Atlantic respond strongly to variations in oxygen and P supply from the Pacific Ocean and to changes in circulation. The implemented N cycle weakly modifies the carbon cycle, implying that P was the major nutrient controlling primary productivity during OAE2. Our model suggests that both N 2 -fixation and upwelling of recycled were enhanced during OAE2 and that N 2 -fixation was the major source of N in the proto-North Atlantic. Denitrification was more important in the water column than in sediments, with high rates in the open ocean and in the Western Interior. High P inputs in the proto-North Atlantic led to widespread N 2 -fixation, which more than compensated for the loss of N through denitrification. As a consequence, rates of primary productivity and organic carbon burial were high.