WE43MEO magnesium foils(thickness≤200μm)were successfully produced via hot rolling.The initially extruded material was heat treated at 450℃for 2 h to achieve a more homogenous microstructure.Afterwards the sheets w...WE43MEO magnesium foils(thickness≤200μm)were successfully produced via hot rolling.The initially extruded material was heat treated at 450℃for 2 h to achieve a more homogenous microstructure.Afterwards the sheets were hot rolled at 480℃in two to five rolling passes to achieve a uniform thickness of less than 200μm and finally heat treated(T5 and T6 heat treatment).After foil rolling and final heat treatment the microstructural und texture evolution as well as resulting mechanical properties were investigated.Therefore,the samples were quenched directly after foil rolling and the final heat treatment.The foil rolling led either to a deformation microstructure(two and three passes)or globular grains(four and five passes)depending on the number of rolling passes.As main recrystallisation mechanisms continuous dynamic recrystallisation(CDRX)and twinning induced dynamic recrystallisation(TDRX)were identified.The resulting textures revealed the activation of non-basal slip of<c+a>-dislocations during prior foil rolling.As a result of the rolling,the strength increased and the elongation decreased compared to the extruded and heat-treated state.Furthermore,it was found that a T6 temper increased corrosion resistance of the tested WE43MEO foils.展开更多
Scaffolds that emulate the architecture of human bone,combined with strong mechanical stability and biocompatibility,are vital for promoting effective bone tissue regeneration.However,most existing bone-mimetic scaffo...Scaffolds that emulate the architecture of human bone,combined with strong mechanical stability and biocompatibility,are vital for promoting effective bone tissue regeneration.However,most existing bone-mimetic scaffolds fall short in reproducing the intricate hierarchical structure of human bone,which restricts their practical application.This study introduces a novel strategy that combines rotational three-dimensional(3D)printing technology and sponge replication technique to fabricate bone-mimetic scaffolds based on composite materials comprising copper-substituted diopside and biphasic calcium phosphate.The scaffolds closely mimic the structure of human bone,featuring both cancellous and cortical bone with Haversian canals.Additionally,the scaffolds exhibit high porosity and transport capacity,while exhibiting compressive strength that is on par with human bone under both axial and lateral loads.Moreover,they demonstrate good biocompatibility and the potential to induce and support osteogenesis and angiogenesis.The scaffolds produced here present a pathway to remediating particularly large bone defects.Given their close resemblance to human bone structure and function,these scaffolds may be well-suited for developing in vitro bone disease models for pharmaceutical testing and various biomedical applications.展开更多
Additive manufacturing(AM) of Ni-base superalloy components can lead to a significant reduction of weight in aerospace applications. AM of IN718 by selective laser melting results in a very fine dendritic microstructu...Additive manufacturing(AM) of Ni-base superalloy components can lead to a significant reduction of weight in aerospace applications. AM of IN718 by selective laser melting results in a very fine dendritic microstructure with a high dislocation density due to the fast solidification process. The complex phase composition of this alloy, with three different types of precipitates and high residual stresses, necessitates adjustment of the conventional heat treatment for AM parts. To find an optimized heat treatment, the microstructures and mechanical properties of differently solution heat-treated samples were investigated by transmission and scanning electron microscopy, including electron backscatter diffraction, and compression tests. After a solution heat treatment(SHT), the Nb-rich Laves phase dissolves and the dislocation density is reduced, which eliminates the dendritic substructure. SHT at 930 or 954°C leads to the precipitation of the δ-phase, which reduces the volume fraction of the strengthening γ′-and γ′′-phases formed during the subsequent two stage aging treatment. With a higher SHT temperature of 1000°C, where no δ-phase is precipitated, higher γ′ and γ′′ volume fractions are achieved, which results in the optimum strength of all of the solution heat treated conditions.展开更多
The reaction between high purity nickel (99.999%) and high purity tin (99.999%) was investigated in the temperature range of 232℃ - 330℃, at short periods of annealing (1 - 60 s). The reaction kinetic was studied us...The reaction between high purity nickel (99.999%) and high purity tin (99.999%) was investigated in the temperature range of 232℃ - 330℃, at short periods of annealing (1 - 60 s). The reaction kinetic was studied using cross-sectional scanning electron microscope (SEM) images. The intermetallic compound (IMC) growth was analyzed using the empirical power law and a time dependence in the range of 0.26 to 0.33 was found. The morphology of the IMC was investigated by SEM in the temperature range of 235℃ - 290℃, at annealing periods of 10 s, 30 s, and 60 s by selectively etching away the remaining elementary tin. The exposed IMC displays a change in morphology with increasing annealing temperature, demonstrating that the growth velocity of certain crystallographic orientations of the IMC is strongly influenced by the annealing temperature. Additionally, coarsening and crumbling of the IMC grains is observed, and will be discussed with respect to the responsible mechanisms.展开更多
One promising joining method for NiTi-SMA （shape memory alloy）-components is laser welding. This joining technology bears huge potential regarding process automation and mechanical properties as well as durability, ...One promising joining method for NiTi-SMA （shape memory alloy）-components is laser welding. This joining technology bears huge potential regarding process automation and mechanical properties as well as durability, especially within the field of small- and medium-sized actuators. However, there is still need for research due to unsolved issues influencing the microstructure and thus effecting mechanical properties as well as SMA-characteristics of these joints. Therefore, the purpose of this paper is the evaluation of quality parameters of NiTi-NiTi-wire-joints. For this purpose, design of experiments with a fractional factorial design is used for the investigation, because of its high potential to decrease experimental effort. This paper provides a basis for future research in the field of SMA-actuators and joining.展开更多
The modern characterizing techniques, which were used forthe determination of the structure of pharmaceutical substancesand products in this presentation, were small angleX-ray scattering (SAXS), photon correlation sp...The modern characterizing techniques, which were used forthe determination of the structure of pharmaceutical substancesand products in this presentation, were small angleX-ray scattering (SAXS), photon correlation spectroscopy (PCS)and transmission electron microscopy (TEM).Different pharmaceutical substances and products such asmodel membranes from fishes, reptiles or carrier systems suchas liposomes, emulsion, and self-emulsifying drug deliverysystems (SEDDs) were characterized in our group by using SAXSfrom a synchrotron source.展开更多
In der Studie wurden 20 Patienten mit AV-Reentry Tachykardie unter Einbezug einer mittelseptalen gelegenen atrioventricul ren akzessorischen Leitungsbahn(MS) eingeschlossen, die seit 4 Jahren in unserem Elektrophysio...In der Studie wurden 20 Patienten mit AV-Reentry Tachykardie unter Einbezug einer mittelseptalen gelegenen atrioventricul ren akzessorischen Leitungsbahn(MS) eingeschlossen, die seit 4 Jahren in unserem Elektrophysiologischen Untersuchungslabor mittels Katheters erfolgreich abladiert wurden. Die 20 Patienten hatten 26 akzessorische Leitungsbahnen. Daunter waren 21 MS (rechtsmittelseptal (RMS) zu linksmittelseptal(LMS)=17:4). 18 akzessorische Leitungsbahnen waren offen. Die Lokalisation der akzessorischen Leitungsbahnen wurde aufgrund der Stelle erfolgreich abladiert bestimmt. Die Ergebnisse zeigten, da die RMS und LMS den gleichen Charakter in den meisten Ableitungen des EKGs hatten, und jedoch der wenige Unterschied bei diesen beiden akzessorischen Lritungsbahnen besteht. Wenn die positive Polaritat der Delta Welle in der Ableitung V 1 bei der Patienten mit MS auftritt, mu sich berlegen, ob die M glichkeit der Lokalisation der akzessorischen Leitungsbahn im Linksmittelseptum besteht.展开更多
Objectives: Aging workforces with increasing numbers of chronic conditions require health initiatives with greater workplace focus. A regional pension insurance introduced a Return To Work (RTW) strategy for insurants...Objectives: Aging workforces with increasing numbers of chronic conditions require health initiatives with greater workplace focus. A regional pension insurance introduced a Return To Work (RTW) strategy for insurants with chronic conditions. The objective was to identify the degree of implementation of work related measures in medical rehabilitation and the extent of RTW outcomes. Methods: 5883 insurants were considered. Severe Restriction of Work Ability (SRWA), Work-related Medical Rehabilitation (WMR), and Case Management (CM) were examined for 2008 and 2012. An Index of Employment status (IoE) was used in a logistic regression. Results: Utilization of WMR raised from 12.3% in 2008 to 66.1% in 2012. The proportion of insurants with SRWA and WMR grew from 8% up to 40.1%. In 2008, 14.7% of insurants with SRWA received WMR;in 2012, it grew to 76.6%. On the other hand, in 2012 26% got WMR without SRWA and 12.2% had SRWA and got no WMR. CM was not conducted in 2008 but reached 20.2% in 2012. Across all indications, WMR resulted in positive RTW as measured by IoE: OR = 0.75 (KI-95%: 0.67 - 0.86). Conclusion: WMR was successfully implemented according to the German guideline. There is a need to optimize the linkage between SRWA and WMR and CM to provide need-based care.展开更多
The hyperfine (hf) structure constants of three atomic niobium energy levels in the energy range around 23000 cm-1 (at 22936.90, 23010.58, and 23048.58 cm-1) are known with only limited accuracy, and the constants of ...The hyperfine (hf) structure constants of three atomic niobium energy levels in the energy range around 23000 cm-1 (at 22936.90, 23010.58, and 23048.58 cm-1) are known with only limited accuracy, and the constants of combining levels are sometimes even unknown. Thus we performed laser spectroscopic investigations in the wavelength range between 5600 and 6500 Å, and we excited altogether 16 transitions in which these lower levels are involved. Beside a more precise determination of the hf structure constants of the three lower levels (which were determined on several lines sharing a common upper level), these experiments led to the knowledge of the hf constants of nine levels with previously unknown constants. Beside these results, also the hf constants of 13 further energy levels are reported. For six of these levels, the constants were previously unknown.展开更多
Die Prim rstabilit t von Pedikelschrauben im Knochen h ngt in hohem Masse von der Knochendichte ab. Die Augmentation mit Zement ist ein klinisch einsetzbares Verfahren, um die Schrauben Verankerung...Die Prim rstabilit t von Pedikelschrauben im Knochen h ngt in hohem Masse von der Knochendichte ab. Die Augmentation mit Zement ist ein klinisch einsetzbares Verfahren, um die Schrauben Verankerung im osteoporotischen Knochen zu verbessern.In dieser Studie wurde eine neuartiges resorbierbares Knochenersatzmaterial (α BSM TM ) für diese Augmentation benutzt. Biomechanische Testungen wurden in vitro bei 16 Lendwirbelk rpern (L3-L5) aus 6 Individuen(75,2±13,7 Jahre) durchgeführt. Vor der biomechanischen Testung wurde bei allen Pr paraten die trabekul re Knochendichte mittels pQCT gemessen und beide Pedikel mit USS Pedikelschrauben (5,0 mm × 45 mm) besetzt, von welchen eine mit α BSM TM augmentiert war. Beim axialen Auszugstest wurden die maximale axiale Auszugskraft (F max) sowie die Energieaufnahme bestimmt. Der Medianwert der F max stieg beim Auszugstest durch die Zementierung mit α BSM TM um 80 % von 370 N (ohne Zement) auf 665 N (mit Zement). Die Energieaufnahme bis zum Erreichen der F max (E F max) und bei Dislokation bis 2,0 mm (E 2 mm) steigerte sich ebenfalls um 83 % und 68 %. Die Unterschiede waren signifikant. (Wilcoxon′s Test, P <0,01) Die Ausreisskrafte F max (ohne oder mit Zement) korrelierten eng mit der Knochendichte ( r =0,9056 und r =0,9585). Unsere Resultate zeigen, da eine Augmentation mit dem α BSM TM die primare Stabilitat von Pedikelschrauben verbessern kann. Der Effekt scheint auf einer Optimierung der Kontaktfl che und einer Aussteifung der schraubennahen Spongiosa zu beruhen. Das Material k nnte geeignet sein, die Verankerung von Pedikelschrauben bei osteoporotischen Patieten zu verbessern.展开更多
An advanced edge-based method of feature detection and extraction is developed for object description in digital images. It is useful for the comparison of different images of the same scene in aerial imagery, for des...An advanced edge-based method of feature detection and extraction is developed for object description in digital images. It is useful for the comparison of different images of the same scene in aerial imagery, for describing and recognizing categories, for automatic building extraction and for finding the mutual regions in image matching. The method includes directional filtering and searching for straight edge segments in every direction and scale, taking into account edge gradient signs. Line segments are ordered with respect to their orientation and average gradients in the region in question. These segments are used for the construction of an object descriptor. A hierarchical set of feature descriptors is developed, taking into consideration the proposed straight line segment detector. Comparative performance is evaluated on the noisy model and in real aerial and satellite imagery.展开更多
文摘WE43MEO magnesium foils(thickness≤200μm)were successfully produced via hot rolling.The initially extruded material was heat treated at 450℃for 2 h to achieve a more homogenous microstructure.Afterwards the sheets were hot rolled at 480℃in two to five rolling passes to achieve a uniform thickness of less than 200μm and finally heat treated(T5 and T6 heat treatment).After foil rolling and final heat treatment the microstructural und texture evolution as well as resulting mechanical properties were investigated.Therefore,the samples were quenched directly after foil rolling and the final heat treatment.The foil rolling led either to a deformation microstructure(two and three passes)or globular grains(four and five passes)depending on the number of rolling passes.As main recrystallisation mechanisms continuous dynamic recrystallisation(CDRX)and twinning induced dynamic recrystallisation(TDRX)were identified.The resulting textures revealed the activation of non-basal slip of<c+a>-dislocations during prior foil rolling.As a result of the rolling,the strength increased and the elongation decreased compared to the extruded and heat-treated state.Furthermore,it was found that a T6 temper increased corrosion resistance of the tested WE43MEO foils.
文摘Scaffolds that emulate the architecture of human bone,combined with strong mechanical stability and biocompatibility,are vital for promoting effective bone tissue regeneration.However,most existing bone-mimetic scaffolds fall short in reproducing the intricate hierarchical structure of human bone,which restricts their practical application.This study introduces a novel strategy that combines rotational three-dimensional(3D)printing technology and sponge replication technique to fabricate bone-mimetic scaffolds based on composite materials comprising copper-substituted diopside and biphasic calcium phosphate.The scaffolds closely mimic the structure of human bone,featuring both cancellous and cortical bone with Haversian canals.Additionally,the scaffolds exhibit high porosity and transport capacity,while exhibiting compressive strength that is on par with human bone under both axial and lateral loads.Moreover,they demonstrate good biocompatibility and the potential to induce and support osteogenesis and angiogenesis.The scaffolds produced here present a pathway to remediating particularly large bone defects.Given their close resemblance to human bone structure and function,these scaffolds may be well-suited for developing in vitro bone disease models for pharmaceutical testing and various biomedical applications.
文摘Additive manufacturing(AM) of Ni-base superalloy components can lead to a significant reduction of weight in aerospace applications. AM of IN718 by selective laser melting results in a very fine dendritic microstructure with a high dislocation density due to the fast solidification process. The complex phase composition of this alloy, with three different types of precipitates and high residual stresses, necessitates adjustment of the conventional heat treatment for AM parts. To find an optimized heat treatment, the microstructures and mechanical properties of differently solution heat-treated samples were investigated by transmission and scanning electron microscopy, including electron backscatter diffraction, and compression tests. After a solution heat treatment(SHT), the Nb-rich Laves phase dissolves and the dislocation density is reduced, which eliminates the dendritic substructure. SHT at 930 or 954°C leads to the precipitation of the δ-phase, which reduces the volume fraction of the strengthening γ′-and γ′′-phases formed during the subsequent two stage aging treatment. With a higher SHT temperature of 1000°C, where no δ-phase is precipitated, higher γ′ and γ′′ volume fractions are achieved, which results in the optimum strength of all of the solution heat treated conditions.
文摘The reaction between high purity nickel (99.999%) and high purity tin (99.999%) was investigated in the temperature range of 232℃ - 330℃, at short periods of annealing (1 - 60 s). The reaction kinetic was studied using cross-sectional scanning electron microscope (SEM) images. The intermetallic compound (IMC) growth was analyzed using the empirical power law and a time dependence in the range of 0.26 to 0.33 was found. The morphology of the IMC was investigated by SEM in the temperature range of 235℃ - 290℃, at annealing periods of 10 s, 30 s, and 60 s by selectively etching away the remaining elementary tin. The exposed IMC displays a change in morphology with increasing annealing temperature, demonstrating that the growth velocity of certain crystallographic orientations of the IMC is strongly influenced by the annealing temperature. Additionally, coarsening and crumbling of the IMC grains is observed, and will be discussed with respect to the responsible mechanisms.
文摘One promising joining method for NiTi-SMA （shape memory alloy）-components is laser welding. This joining technology bears huge potential regarding process automation and mechanical properties as well as durability, especially within the field of small- and medium-sized actuators. However, there is still need for research due to unsolved issues influencing the microstructure and thus effecting mechanical properties as well as SMA-characteristics of these joints. Therefore, the purpose of this paper is the evaluation of quality parameters of NiTi-NiTi-wire-joints. For this purpose, design of experiments with a fractional factorial design is used for the investigation, because of its high potential to decrease experimental effort. This paper provides a basis for future research in the field of SMA-actuators and joining.
文摘The modern characterizing techniques, which were used forthe determination of the structure of pharmaceutical substancesand products in this presentation, were small angleX-ray scattering (SAXS), photon correlation spectroscopy (PCS)and transmission electron microscopy (TEM).Different pharmaceutical substances and products such asmodel membranes from fishes, reptiles or carrier systems suchas liposomes, emulsion, and self-emulsifying drug deliverysystems (SEDDs) were characterized in our group by using SAXSfrom a synchrotron source.
文摘In der Studie wurden 20 Patienten mit AV-Reentry Tachykardie unter Einbezug einer mittelseptalen gelegenen atrioventricul ren akzessorischen Leitungsbahn(MS) eingeschlossen, die seit 4 Jahren in unserem Elektrophysiologischen Untersuchungslabor mittels Katheters erfolgreich abladiert wurden. Die 20 Patienten hatten 26 akzessorische Leitungsbahnen. Daunter waren 21 MS (rechtsmittelseptal (RMS) zu linksmittelseptal(LMS)=17:4). 18 akzessorische Leitungsbahnen waren offen. Die Lokalisation der akzessorischen Leitungsbahnen wurde aufgrund der Stelle erfolgreich abladiert bestimmt. Die Ergebnisse zeigten, da die RMS und LMS den gleichen Charakter in den meisten Ableitungen des EKGs hatten, und jedoch der wenige Unterschied bei diesen beiden akzessorischen Lritungsbahnen besteht. Wenn die positive Polaritat der Delta Welle in der Ableitung V 1 bei der Patienten mit MS auftritt, mu sich berlegen, ob die M glichkeit der Lokalisation der akzessorischen Leitungsbahn im Linksmittelseptum besteht.
文摘Objectives: Aging workforces with increasing numbers of chronic conditions require health initiatives with greater workplace focus. A regional pension insurance introduced a Return To Work (RTW) strategy for insurants with chronic conditions. The objective was to identify the degree of implementation of work related measures in medical rehabilitation and the extent of RTW outcomes. Methods: 5883 insurants were considered. Severe Restriction of Work Ability (SRWA), Work-related Medical Rehabilitation (WMR), and Case Management (CM) were examined for 2008 and 2012. An Index of Employment status (IoE) was used in a logistic regression. Results: Utilization of WMR raised from 12.3% in 2008 to 66.1% in 2012. The proportion of insurants with SRWA and WMR grew from 8% up to 40.1%. In 2008, 14.7% of insurants with SRWA received WMR;in 2012, it grew to 76.6%. On the other hand, in 2012 26% got WMR without SRWA and 12.2% had SRWA and got no WMR. CM was not conducted in 2008 but reached 20.2% in 2012. Across all indications, WMR resulted in positive RTW as measured by IoE: OR = 0.75 (KI-95%: 0.67 - 0.86). Conclusion: WMR was successfully implemented according to the German guideline. There is a need to optimize the linkage between SRWA and WMR and CM to provide need-based care.
文摘The hyperfine (hf) structure constants of three atomic niobium energy levels in the energy range around 23000 cm-1 (at 22936.90, 23010.58, and 23048.58 cm-1) are known with only limited accuracy, and the constants of combining levels are sometimes even unknown. Thus we performed laser spectroscopic investigations in the wavelength range between 5600 and 6500 Å, and we excited altogether 16 transitions in which these lower levels are involved. Beside a more precise determination of the hf structure constants of the three lower levels (which were determined on several lines sharing a common upper level), these experiments led to the knowledge of the hf constants of nine levels with previously unknown constants. Beside these results, also the hf constants of 13 further energy levels are reported. For six of these levels, the constants were previously unknown.
文摘Die Prim rstabilit t von Pedikelschrauben im Knochen h ngt in hohem Masse von der Knochendichte ab. Die Augmentation mit Zement ist ein klinisch einsetzbares Verfahren, um die Schrauben Verankerung im osteoporotischen Knochen zu verbessern.In dieser Studie wurde eine neuartiges resorbierbares Knochenersatzmaterial (α BSM TM ) für diese Augmentation benutzt. Biomechanische Testungen wurden in vitro bei 16 Lendwirbelk rpern (L3-L5) aus 6 Individuen(75,2±13,7 Jahre) durchgeführt. Vor der biomechanischen Testung wurde bei allen Pr paraten die trabekul re Knochendichte mittels pQCT gemessen und beide Pedikel mit USS Pedikelschrauben (5,0 mm × 45 mm) besetzt, von welchen eine mit α BSM TM augmentiert war. Beim axialen Auszugstest wurden die maximale axiale Auszugskraft (F max) sowie die Energieaufnahme bestimmt. Der Medianwert der F max stieg beim Auszugstest durch die Zementierung mit α BSM TM um 80 % von 370 N (ohne Zement) auf 665 N (mit Zement). Die Energieaufnahme bis zum Erreichen der F max (E F max) und bei Dislokation bis 2,0 mm (E 2 mm) steigerte sich ebenfalls um 83 % und 68 %. Die Unterschiede waren signifikant. (Wilcoxon′s Test, P <0,01) Die Ausreisskrafte F max (ohne oder mit Zement) korrelierten eng mit der Knochendichte ( r =0,9056 und r =0,9585). Unsere Resultate zeigen, da eine Augmentation mit dem α BSM TM die primare Stabilitat von Pedikelschrauben verbessern kann. Der Effekt scheint auf einer Optimierung der Kontaktfl che und einer Aussteifung der schraubennahen Spongiosa zu beruhen. Das Material k nnte geeignet sein, die Verankerung von Pedikelschrauben bei osteoporotischen Patieten zu verbessern.
文摘An advanced edge-based method of feature detection and extraction is developed for object description in digital images. It is useful for the comparison of different images of the same scene in aerial imagery, for describing and recognizing categories, for automatic building extraction and for finding the mutual regions in image matching. The method includes directional filtering and searching for straight edge segments in every direction and scale, taking into account edge gradient signs. Line segments are ordered with respect to their orientation and average gradients in the region in question. These segments are used for the construction of an object descriptor. A hierarchical set of feature descriptors is developed, taking into consideration the proposed straight line segment detector. Comparative performance is evaluated on the noisy model and in real aerial and satellite imagery.
