The thermal structure of subduction zones exerts a major influence on deep-seated mechanical and chemical processes controlling arc magmatism, seismicity, and global element cycles. Accretionary complexes exposed inla...The thermal structure of subduction zones exerts a major influence on deep-seated mechanical and chemical processes controlling arc magmatism, seismicity, and global element cycles. Accretionary complexes exposed inland may comprise tectonic blocks with contrasting pressureetemperature(Pe T)histories, making it possible to investigate the dynamics and thermal evolution of former subduction interfaces. With this aim, we present new Lue Hf geochronological results for mafic rocks of the Halilbag?Complex(Anatolia) that evolved along different thermal gradients. Samples include a lawsoniteeepidote blueschist, a lawsoniteeepidote eclogite, and an epidote eclogite(all with counter-clockwise Pe T paths),a prograde lawsonite blueschist with a "hairpin"-type Pe T path, and a garnet amphibolite from the overlying sub-ophiolitic metamorphic sole. Equilibrium phase diagrams suggest that the garnet amphibolite formed at w0.6 -0.7 GPa and 800 -850℃, whereas the prograde lawsonite blueschist records burial from 2.1 GPa and 420℃ to 2.6 GPa and 520℃. Well-defined Lue Hf isochrons were obtained for the epidote eclogite(92.38 ± 0.22 Ma) and the lawsoniteeepidote blueschist(90.19 ± 0.54 Ma),suggesting rapid garnet growth. The lawsoniteeepidote eclogite(87.30 ± 0.39 Ma) and the prograde lawsonite blueschist(ca. 86 Ma) are younger, whereas the garnet amphibolite(104.5 ± 3.5 Ma) is older.Our data reveal a consistent trend of progressively decreasing geothermal gradient from granulite-facies conditions at ~104 Ma to the epidote-eclogite facies around 92 Ma, and the lawsonite blueschist-facies between 90 Ma and 86 Ma. Three Lue Hf garnet dates(between 92 Ma and 87 Ma) weighted toward the growth of post-peak rims(as indicated by Lu distribution in garnet) suggest that the HP/LT rocks were exhumed continuously and not episodically. We infer that HP/LT metamorphic rocks within the Halilbag?Complex were subjected to continuous return flow, with "warm" rocks being exhumed during the tectonic burial of "cold" ones. Our results, combined with regional geological constraints, allow us to speculate that subduction started at a transform fault near a mid-oceanic spreading centre. Following its formation, this ancient subduction interface evolved thermally over more than 15 Myr, most likely as a result of heat dissipation rather than crustal underplating.展开更多
Nanoparticles are able to interact with biomolecules, creating functional nanosystems for transportation within in vivo cells, and leading to the study of their potential applications in the field of plant biotechnolo...Nanoparticles are able to interact with biomolecules, creating functional nanosystems for transportation within in vivo cells, and leading to the study of their potential applications in the field of plant biotechnology. Therefore, the aim of this research was to determine the growth and rooting effect of functionalized (SWCNTs-COOH) and non-functionalized nanoparticles with iron residue inner particles (SWCNTs-Fe) in blackberry (Rubus adenotrichos) in vitro plants. Two types of SWCNTs were used, both of them characterized in a solid sample through Raman spectroscopy (λ = 532 nm) showing differences in the G band between SWCNT + Fe and SWCNT + COOH. The in vitro plants (approximately 15 mm length) were inoculated in a rooting medium. Six treatments were established: 4, 8, 12 μg/ml for each type of SWCNTs and a control without nanotubes. The assessed variables consisted of the average number of days for root emergence, average number of roots per plant, average root length per plant and the average stem length. This study determined that, in general, the SWCNTs-COOH promoted the growth of the in vitro plants under this assay, when compared to the SWCNTs-Fe trials. The lowest SWCNTs-COOH dose evidenced the best results for the assessed variables. Additionally, the histological analysis also evidenced that the plants treated with SWCNTs-COOH nanotubes (4 μg/ml) increased their cellular metabolism when compared to the control group.展开更多
Many processes may be used for manufacturing functionally graded materials.Among them,additive manufacturing seems to be predestined due to near-net shape manufacturing of complex geometries combined with the possibil...Many processes may be used for manufacturing functionally graded materials.Among them,additive manufacturing seems to be predestined due to near-net shape manufacturing of complex geometries combined with the possibility of applying different materials in one component.By adjusting the powder composition of the starting material layer by layer,a macroscopic and step-like gradient can be achieved.To further improve the step-like gradient,an enhancement of the in-situ mixing degree,which is limited according to the state of the art,is necessary.In this paper,a novel technique for an enhancement of the in-situ material mixing degree in the melt pool by applying laser remelting(LR)is described.The effect of layer-wise LR on the formation of the interface was investigated using pure copper and low-alloy steel in a laser powder bed fusion process.Subsequent cross-sectional selective electron microscopic analyses were carried out.By applying LR,the mixing degree was enhanced,and the reaction zone thickness between the materials was increased.Moreover,an additional copper and iron-based phase was formed in the interface,resulting in a smoother gradient of the chemical composition than the case without LR.The Marangoni convection flow and thermal diffusion are the driving forces for the observed effect.展开更多
The wetting behavior of liquid metals is of great importance for many processes. For brazing, however, a targeted modification beyond the adjustment of conventional process parameters or the actual set-up was not poss...The wetting behavior of liquid metals is of great importance for many processes. For brazing, however, a targeted modification beyond the adjustment of conventional process parameters or the actual set-up was not possible in the past. Therefore, the effect of direct electric current along the surface of a steel substrate on the wetting behavior and the formation of the spreading pattern of an industrial nickel-based filler metal was investigated at a temperature above T = 1000 °C in a vacuum brazing furnace. By applying direct current up to I = 60 A the wetted surface area could be increased and the spreading of the molten filler metal could be controlled in dependence of the polarity of the electric current. The electric component of the Lorentz force is supposed to be feasible reasons for the observed dependence of the electrical polarity on the filler metal spreading direction. To evaluate the influence of the electric current on the phase formation subsequent selective electron microscope analyses of the spreading pattern were carried out.展开更多
基金Funding by the Deutsche Forschungsgemeinschaft (projectPO17-91)
文摘The thermal structure of subduction zones exerts a major influence on deep-seated mechanical and chemical processes controlling arc magmatism, seismicity, and global element cycles. Accretionary complexes exposed inland may comprise tectonic blocks with contrasting pressureetemperature(Pe T)histories, making it possible to investigate the dynamics and thermal evolution of former subduction interfaces. With this aim, we present new Lue Hf geochronological results for mafic rocks of the Halilbag?Complex(Anatolia) that evolved along different thermal gradients. Samples include a lawsoniteeepidote blueschist, a lawsoniteeepidote eclogite, and an epidote eclogite(all with counter-clockwise Pe T paths),a prograde lawsonite blueschist with a "hairpin"-type Pe T path, and a garnet amphibolite from the overlying sub-ophiolitic metamorphic sole. Equilibrium phase diagrams suggest that the garnet amphibolite formed at w0.6 -0.7 GPa and 800 -850℃, whereas the prograde lawsonite blueschist records burial from 2.1 GPa and 420℃ to 2.6 GPa and 520℃. Well-defined Lue Hf isochrons were obtained for the epidote eclogite(92.38 ± 0.22 Ma) and the lawsoniteeepidote blueschist(90.19 ± 0.54 Ma),suggesting rapid garnet growth. The lawsoniteeepidote eclogite(87.30 ± 0.39 Ma) and the prograde lawsonite blueschist(ca. 86 Ma) are younger, whereas the garnet amphibolite(104.5 ± 3.5 Ma) is older.Our data reveal a consistent trend of progressively decreasing geothermal gradient from granulite-facies conditions at ~104 Ma to the epidote-eclogite facies around 92 Ma, and the lawsonite blueschist-facies between 90 Ma and 86 Ma. Three Lue Hf garnet dates(between 92 Ma and 87 Ma) weighted toward the growth of post-peak rims(as indicated by Lu distribution in garnet) suggest that the HP/LT rocks were exhumed continuously and not episodically. We infer that HP/LT metamorphic rocks within the Halilbag?Complex were subjected to continuous return flow, with "warm" rocks being exhumed during the tectonic burial of "cold" ones. Our results, combined with regional geological constraints, allow us to speculate that subduction started at a transform fault near a mid-oceanic spreading centre. Following its formation, this ancient subduction interface evolved thermally over more than 15 Myr, most likely as a result of heat dissipation rather than crustal underplating.
文摘Nanoparticles are able to interact with biomolecules, creating functional nanosystems for transportation within in vivo cells, and leading to the study of their potential applications in the field of plant biotechnology. Therefore, the aim of this research was to determine the growth and rooting effect of functionalized (SWCNTs-COOH) and non-functionalized nanoparticles with iron residue inner particles (SWCNTs-Fe) in blackberry (Rubus adenotrichos) in vitro plants. Two types of SWCNTs were used, both of them characterized in a solid sample through Raman spectroscopy (λ = 532 nm) showing differences in the G band between SWCNT + Fe and SWCNT + COOH. The in vitro plants (approximately 15 mm length) were inoculated in a rooting medium. Six treatments were established: 4, 8, 12 μg/ml for each type of SWCNTs and a control without nanotubes. The assessed variables consisted of the average number of days for root emergence, average number of roots per plant, average root length per plant and the average stem length. This study determined that, in general, the SWCNTs-COOH promoted the growth of the in vitro plants under this assay, when compared to the SWCNTs-Fe trials. The lowest SWCNTs-COOH dose evidenced the best results for the assessed variables. Additionally, the histological analysis also evidenced that the plants treated with SWCNTs-COOH nanotubes (4 μg/ml) increased their cellular metabolism when compared to the control group.
文摘Many processes may be used for manufacturing functionally graded materials.Among them,additive manufacturing seems to be predestined due to near-net shape manufacturing of complex geometries combined with the possibility of applying different materials in one component.By adjusting the powder composition of the starting material layer by layer,a macroscopic and step-like gradient can be achieved.To further improve the step-like gradient,an enhancement of the in-situ mixing degree,which is limited according to the state of the art,is necessary.In this paper,a novel technique for an enhancement of the in-situ material mixing degree in the melt pool by applying laser remelting(LR)is described.The effect of layer-wise LR on the formation of the interface was investigated using pure copper and low-alloy steel in a laser powder bed fusion process.Subsequent cross-sectional selective electron microscopic analyses were carried out.By applying LR,the mixing degree was enhanced,and the reaction zone thickness between the materials was increased.Moreover,an additional copper and iron-based phase was formed in the interface,resulting in a smoother gradient of the chemical composition than the case without LR.The Marangoni convection flow and thermal diffusion are the driving forces for the observed effect.
基金The presented investigations were carried out at RWTH Aachen University within the framework of the Collaborative Research Centre SFB1120-236616214“Precision Melt Engineering”and funded by the German Research Foundation(DFG e.V.).
文摘The wetting behavior of liquid metals is of great importance for many processes. For brazing, however, a targeted modification beyond the adjustment of conventional process parameters or the actual set-up was not possible in the past. Therefore, the effect of direct electric current along the surface of a steel substrate on the wetting behavior and the formation of the spreading pattern of an industrial nickel-based filler metal was investigated at a temperature above T = 1000 °C in a vacuum brazing furnace. By applying direct current up to I = 60 A the wetted surface area could be increased and the spreading of the molten filler metal could be controlled in dependence of the polarity of the electric current. The electric component of the Lorentz force is supposed to be feasible reasons for the observed dependence of the electrical polarity on the filler metal spreading direction. To evaluate the influence of the electric current on the phase formation subsequent selective electron microscope analyses of the spreading pattern were carried out.
