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Development of CO2 Selective Poly（Ethylene Oxide）-Based Membranes： From Laboratory to Pilot Plant Scale

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Engineering 2017年第4期3卷 485-493页

作者： Torsten Brinkmann Jelena Lilleparg Heiko Notzke Jan Pohlmann Sergey Shishatskiy Jan Wind Thorsten Wolff Institute of Polymer Research Helmholtz-Zentrum Geesthacht Geesthacht 21502 Germany

Membrane gas separation is one of the most promising technologies for the separation of carbon dioxide （CO2） from various gas streams. One application of this technology is the treatment of flue gases from combustion processes for the purpose of carbon capture and storage. For this application, poly（ethylene oxide）-containing block copolymers such as Pebax or PolyActiveTM polymer are well suited. The thin-film composite membrane that is considered in this overview employs PolyActiveTM polymer as a selective layer material. The membrane shows excellent CO2 permeances of up to 4 m^3（STP）.（m^2·h·bar）^-1 （1 bar = 105 Pa） at a carbon dioxide/nitrogen （CO2/N2） selectivity exceeding 55 at ambient temperature. The membrane can be manufactured reproducibly on a pilot scale and mounted into fiat-sheet membrane modules of different designs. The operating performance of these modules can be accurately predicted by specifically developed simulation tools, which employ single-gas permeation data as the only experimental input. The performance of membranes and modules was investigated in different pilot plant studies, in which flue gas and biogas were used as the feed gas streams. The investigated processes showed a stable separation performance, indicating the applicability of PolyActiveTM polymer as a membrane material for industrialscale gas processing.

关键词： Gas permeation Thin-film composite membrane CO2 separation Carbon capture and storage Biogas processing Membrane modules

FerryBox: Using Automated Water Measurement Systems to Monitor Water Quality: Perspectives for the Yangtze River and Three Gorges Dam

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Journal of Earth Science 2010年第6期21卷 861-869页

作者： Carsten Frank Friedhelm Schroeder Wilhelm Petersen helmholtz-zentrum geesthacht GmbH Institute for Coastal Research

The building of the Three Gorges Dam （Hubei （湖北） Province, China） has transformed a region with an economy based on sustainable agriculture for millennia into an entirely different environment within an exceptionally short time. This disrupts the natural biogeochemieal cycles of carbon, nutrients, and metals and possibly will affect the whole catchment including downstream ecosystems, such as wetlands, estuaries, deltas, and adjacent sea areas. Starting from changes that have already been documented, this article concentrates on the possible use of a ＂FerryBox＂, which is an automated water quality measurement system on board a ship or on shore, to monitor the short and long term development of the quality of the river water in the backwater area and downstream of the dam. While there are already research programmes running to monitor the water quality of the river and the backwater area, these programs are limited to ship campaigns with sampling and laboratory analysis. The spatial and temporal resolution of such measurements is not sufficient for an overall assessment of the water quality and for prognoses in the context of anthropogenic and climate change. Therefore, a concept of applying regular automated observations by a FerryBox is presented. It is shown that such systems are very well suited to give feedback for the assessment of measures to improve the water quality.

关键词： Three Gorges Dam Yangtze River eutrophication FerryBox.

Mechanisms and anisotropy of serrated flow in Mg-Gd single crystals

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Journal of Magnesium and Alloys 2023年第5期11卷 1643-1655页

作者： Henry Ovri helmholtz zentrum Hereon Institute of Materials Mechanics21502 GeesthachtGermany

Serrated flow has been primarily studied at the macron scale,yet the length and times scales at which the solute-meditated dislocation pinning and de-pinning processes that underlie the phenomenon occur are largely inaccessible by macroscopic ***,direct insights into the dominant slip systems in the serrated flow regime,which is particularly critical in Mg alloys given their high plastic anisotropy,requires the use of small-scale testing methods such as ***,in this work,a combination of microcompression and TEM based EDS/STEM measurements have used to critically study the temperature and strain rate dependences in single crystals of pure Mg and a Mg-Gd alloy oriented for twinning,basal-,prismatic-,and *** results provide compelling evidence that the solute drag mechanism underlie serrated flow in the alloy;they also show that serrated flow in Mg alloys is markedly *** anisotropy is caused by differences between the Burgers vector for slip/twinning,and between the impurity diffusivity along/perpendicular to the basal plane.

关键词： Microcompression Mg-RE Mg-Gd Pure Mg Serrated flow Solute drag STEM

Detailing the influence of PEO-coated biodegradable Mg-based implants on the lacuno-canalicular network in sheep bone:A pilot study

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Bioactive Materials 2023年第8期26卷 14-23页

作者： Jonathan Espiritu Sandra Sefa Hanna Cwieka Imke Greving Silja Flenner Regine Willumeit-Römer Jan-Marten Seitz Berit Zeller-Plumhoff Syntellix AG HannoverGermany Institute of Metallic Biomaterials Helmholtz-Zentrum HereonGeesthachtGermany Institute of Materials Physics Helmholtz-Zentrum HereonGeesthachtGermany

An increasing prevalence of bone-related injuries and aging geriatric populations continue to drive the orthopaedic implant market.A hierarchical analysis of bone remodelling after material implantation is necessary to better understand the relationship between implant and ***,which are housed and communicate through the lacuno-canalicular network(LCN),are integral to bone health and remodelling ***,it is essential to examine the framework of the LCN in response to implant materials or surface *** materials offer an alternative solution to permanent implants,which may require revision or removal *** alloys have resurfaced as promising materials due to their bone-like properties and safe degradation in *** further tailor their degradation capabilities,surface treatments such as plasma electrolytic oxidation(PEO)have demonstrated to slow *** the first time,the influence of a biodegradable material on the LCN is investigated by means of non-destructive 3D *** this pilot study,we hypothesize noticeable variations in the LCN caused by altered chemical stimuli introduced by the *** synchrotron-based transmission X-ray microscopy,we have characterised morphological LCN differences around uncoated and PEO-coated WE43 screws implanted into sheep *** specimens were explanted after 4,8,and 12 weeks and regions near the implant surface were prepared for *** from this investigation indicate that the slower degradation of PEO-coated WE43 induces healthier lacunar shapes within the ***,the stimuli perceived by the uncoated material with higher degradation rates induces a greater connected LCN better prepared for bone disturbance.

关键词： Nanotomography Lacuno-canalicular network Bone Magnesium Biodegradable implants

Alloying effect of silver in magnesium on the development of microstructure and mechanical properties by indirect extrusion

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Journal of Magnesium and Alloys 2021年第1期9卷 112-122页

作者： Bjorn Wiese Regine Willumeit-Römer Dietmar Letzig Jan Bohlen Division Metallic Biomaterials Institute of Materials ResearchHelmholtz-Zentrum GeesthachtMax-Planck-Str.1Geesthacht 21502Germany Magnesium Innovation Center(MagIC) Institute of Materials ResearchHelmholtz-Zentrum GeesthachtMax-Planck-Str.1Geesthacht 21502Germany

The effect of Ag in solid solution on the microstructure,texture and the deformation behaviour of indirectly extruded Mg was *** as a solid solution strengthener affects the behaviour during extrusion,resulting in enhanced deformation related heating and corresponding coarser grained *** substantial effect on the texture development is *** mechanical properties simultaneously increase in stress and strain levels with increasing Ag content,especially in tension as a result of the changing impact of the slip modes which can be associated with a decrease of the lattice parameters as well as the c/a ratio of the hcp lattice *** compression tests with twin dominated flow,the impact is much smaller on the compressive yield stress but higher with respect to the twinning related strain hardening *** solution strength functions for Fleischer and Labusch were determined,also confirming the anisotropic behaviour of the extruded Mg alloys.

关键词： Mg-Ag-alloys Lattice parameters Indirect extrusion Microstructure Mechanical properties

Pore characterization of PM Mg–0.6Ca alloy and its degradation behavior under physiological conditions

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Journal of Magnesium and Alloys 2021年第2期9卷 686-703页

作者： Eshwara Phani Shubhakar Nidadavolu Diana Krüger Berit Zeller-Plumhoff Domonkos Tolnai Björn Wiese Frank Feyerabend Thomas Ebel Regine Willumeit-Römer Division Metallic Biomaterials Institute of Materials ResearchHelmholtz-Zentrum GeesthachtMax-Planck-Str.1Geesthacht 21502Germany Magnesium Innovation Center(MagIC) Institute of Materials ResearchHelmholtz-Zentrum GeesthachtMax-Planck-Str.1Geesthacht 21502Germany

Several material parameters affect degradation characteristics of Mg and its alloys under physiological *** Mg materials are interesting for their simultaneous degradation and drug delivery ***,an increase in pore surface area is detrimental to both degradation resistance and subsequent mechanical *** present work aims at determining the threshold porosity value in Mg–0.6 Ca specimens produced by powder metallurgy(PM)below which low degradation rates persist with acceptable mechanical *** different porous Mg–0.6 Ca specimens containing both closed and open pore structures were fabricated with porosities ranging from 3%to 21%.Degradation profiles were obtained via a semi static immersion test over 16 days under physiological conditions using Dulbecco’s modified Eagle’s medium with Glutamax and 10%fetal bovine serum as *** results are related to morphological pore parameters like pore size distribution,pore interconnectivity and pore curvatures that were quantified using an ex situμCT *** general,with decreasing porosity a decrease in pore interconnectivity is seen followed by rounding of the *** degradation rates(MDR<0.3 mm/year)are observed in specimens until 10%porosity,however,the upper bound for reproducible degradation is observed to be in specimens until 12%*** porosity level also marks the transition from closed to open pore nature with a simultaneous change in pore interconnectivity from less than 10%to greater than 95%,below and above this porosity level,*** tensile strength and elongation to failure recorded for specimens with 10%porosity were 70 MPa and 2%,respectively displaying positive traits of both homogenous degradation and mechanical *** results suggest that high pore interconnectivity is the dominant factor controlling degradation and mechanical properties in porous Mg-0.6 Ca *** results also indicate a good sintering respons

关键词： Porous Mg-0.6Ca In vitro Degradation μCT Sintering

Chinese lockdown as aerosol reduction experiment

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Advances in Climate Change Research 2021年第5期12卷 677-685页

作者： Hans VON STORCH Beate GEYER LI Yan Volker MATTHIAS Burkhardt ROCKEL Institute of Coastal Systems Helmholtz-Zentrum GeesthachtGeesthacht21502Germany Ocean University of China Qingdao266100China College of Life Sciences and Oceanography Shenzhen UniversityShenzhen518061China Institute of Biogeochemistry in Coastal Seas Helmholtz-Zentrum GeesthachtGeesthacht21502Germany

The lockdown of large parts of Chinese economy beginning in late January 2020 lead to significant regional changes of aerosol loads, which suggests a reduction of backscatter and consequently a regional warming in the following months. Using local data and a numerical experiment with a limited area model, we have examined how strong this response may have been. The observed (local and reanalysis) observations point to a warming of less than 1.0 K, the simulations to a warming of the order of 0.5 K. These numbers are uncertain, because of large-scale natural variability and an ad-hoc choice of aerosol optical depth anomaly in the simulation. Thus, the result was, in short, that there was actually a weak warming of a few tenth of degrees, while noteworthy changes in circulation or in precipitation were not detected. More specifically, we found that at selected central China stations temperatures were found to be higher than in previous two years. This warming goes with a marked diurnal signal, with a maximum warming in the early afternoon (06 UTC), weakest at night (18 UTC). This may be related to a general warming of large swaths of Asia (including Siberia, which is not related to local aerosol forcing). Indeed, also the stations outside the immediate strong lockdown region are showing warming, albeit a weaker one. Thus, the difference 2020 minus 2019/2018 may overestimate the effect. The ad-hoc series of numerical experiments indicates that the simulated changes are robust and suffer little from internal dynamical variability. In particular, the overall reduction of the aerosol optical depth does not lead to phases of larger intermittent divergence among the model simulations, irrespective of the aerosol load. Instead, the simulations with reduced anthropogenic aerosol load show more a mere locally increased temperature. This may indicate that the aerosol effect is mostly thermodynamic in all local air columns in the region.

关键词： Lockdown China Aerosol Climate

Computational modelling of magnesium degradation in simulated body fluid under physiological conditions

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Journal of Magnesium and Alloys 2022年第4期10卷 965-978页

作者： Berit Zeller-Plumhoff Tamadur AlBaraghtheh Daniel Höche Regine Willumeit-Römer helmholtz-zentrum hereon GmbH Institute of Metallic BiomaterialsMax-Planck-Straße 1Geesthacht21502Germany helmholtz-zentrum hereon GmbH Institute of Surface ScienceMax-Planck-Straße 1Geesthacht21502Germany

Magnesium alloys are highly attractive for the use as temporary implant materials, due to their high biocompatibility and ***, the prediction of the degradation rate of the implants is difficult, therefore, a large number of experiments are required. Computational modelling can aid in enabling the predictability, if sufficiently accurate models can be established. This work presents a generalized model of the degradation of pure magnesium in simulated body fluid over the course of 28 days considering uncertainty aspects. The model includes the computation of the metallic material thinning and is calibrated using the mean degradation depth of several experimental datasets simultaneously. Additionally, the formation and precipitation of relevant degradation products on the sample surface is modelled, based on the ionic composition of simulated body fluid. The computed mean degradation depth is in good agreement with the experimental data(NRMSE=0.07). However, the quality of the depth profile curves of the determined elemental weight percentage of the degradation products differs between elements(such as NRMSE=0.40 for phosphorus vs. NRMSE=1.03 for magnesium). This indicates that the implementation of precipitate formation may need further developments. The sensitivity analysis showed that the model parameters are correlated and which is related to the complexity and the high computational costs of the model. Overall, the model provides a correlating fit to the experimental data of pure Mg samples of different geometries degrading in simulated body fluid with reliable error estimation.

关键词： Biodegradation Magnesium Computational modelling Corrosion Uncertainty quantification Kriging

Comparison between compression tested and simulated Mg-6.3Gd bone scaffolds produced by binder based additive manufacturing technique

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Journal of Magnesium and Alloys 2023年第8期11卷 2750-2762页

作者： Martin Wolff Mohammad Marvi-Mashhadi Eshwara Nidadavolu Henrik Lüneburg Thomas Ebel Regine Willumeit-Römer Institute of Metallic Biomaterials at helmholtz-zentrum Hereon Max-Planck Str.1D-21502 GeesthachtGermany Institute of Material Systems Modeling Helmholtz-Zentrum HereonMax–Planck-Str.121502 GeesthachtGermany

In this study,a binder based 3D-printing technology *** Granular Fabrication(FGF)technique was used to produce interconnected and open porous Mg-6.3Gd bone scaffolds for compression test *** consolidation of the green parts(as printed scaffolds)was performed using solvent debinding in cyclohexane and subsequent conventional sintering in argon *** tests were performed on as sintered ***,a simulation strategy was developed for modeling the compression behavior of the sintered parts,utilizing the data from the experimental *** experimental compression test results and the simulation strategy for the compression behavior of the 3D-printed scaffolds demonstrated good agreement.

关键词： Magnesium Mg-6.3Gd Additive manufacturing Simulation FGF Biodegradable