Position-dependent shear-induced austenite-martensite transformation in double-notched TRIP and dual-phase steel samples

While earlier studies on transformation-induced-plasticity (TRIP) steels focused on the determination of the austenite-to-martensite decomposition in uniform deformation or thermal fields, the current research focuses on the determination of the local retained austenite-to-martensite transformation behaviour in an inhomogeneous yet carefully controlled shear-loaded region of double-notched TRIP and dual-phase (DP) steel samples. A detailed powder analysis has been performed to simultaneously monitor the evolution of the phase fraction and the changes in average carbon concentration of metastable austenite together with the local strain components in the constituent phases as a function of the macroscopic stress and location with respect to the shear band. The metastable retained austenite shows a mechanically induced martensitic transformation in the localized shear zone, which is accompanied by an increase in average carbon concentration of the remaining austenite due to a preferred transformation of the austenite grains with the lowest carbon concentration. At the later deformation stages the geometry of the shear test samples results in the development of an additional tensile component. The experimental strain field within the probed sample area is in good agreement with finite element calculations. The strain development observed in the low-alloyed TRIP steel with metastable austenite is compared with that of steels with the same chemical composition containing either no austenite (a DP grade) or stable retained austenite (a TRIP grade produced at a long bainitic holding time). The transformation of metastable austenite under shear is a complex interplay between the local microstructure and the evolving strain fields

Early pH Changes in Musculoskeletal Tissues upon Injury-Aerobic Catabolic Pathway Activity Linked to Inter-Individual Differences in Local pH

Local pH is stated to acidify after bone fracture. However, the time course and degree of acidification remain unknown. Whether the acidification pattern within a fracture hematoma is applicable to adjacent muscle hematoma or is exclusive to this regenerative tissue has not been studied to date. Thus, in this study, we aimed to unravel the extent and pattern of acidification in vivo during the early phase post musculoskeletal injury. Local pH changes after fracture and muscle trauma were measured simultaneously in two pre-clinical animal models (sheep/rats) immediately after and up to 48 h post injury. The rat fracture hematoma was further analyzed histologically and metabolomically. In vivo pH measurements in bone and muscle hematoma revealed a local acidification in both animal models, yielding mean pH values in rats of 6.69 and 6.89, with pronounced intra- and inter-individual differences. The metabolomic analysis of the hematomas indicated a link between reduction in tricarboxylic acid cycle activity and pH, thus, metabolic activity within the injured tissues could be causative for the different pH values. The significant acidification within the early musculoskeletal hematoma could enable the employment of the pH for novel, sought-after treatments that allow for spatially and temporally controlled drug release

The Bell Theorem as a Special Case of a Theorem of Bass

The theorem of Bell states that certain results of quantum mechanics violate inequalities that are valid for objective local random variables. We show that the inequalities of Bell are special cases of theorems found ten years earlier by Bass and stated in full generality by Vorob'ev. This fact implies precise necessary and sufficient mathematical conditions for the validity of the Bell inequalities. We show that these precise conditions differ significantly from the definition of objective local variable spaces and as an application that the Bell inequalities may be violated even for objective local random variables.Comment: 15 pages, 2 figure

Machine Learning Assisted Design of Experiments for Solid State Electrolyte Lithium Aluminum Titanium Phosphate

Lithium-ion batteries with solid electrolytes offer safety, higher energy density and higher long-term performance, which are promising alternatives to conventional liquid electrolyte batteries. Lithium aluminum titanium phosphate (LATP) is one potential solid electrolyte candidate due to its high Li-ion conductivity. To evaluate its performance, influences of the experimental factors on the materials design need to be investigated systematically. In this work, a materials design strategy based on machine learning (ML) is employed to design experimental conditions for the synthesis of LATP. In the variation of parameters, we focus on the tolerance against the possible deviations in the concentration of the precursors, as well as the influence of sintering temperature and holding time. Specifically, models built with different design selection strategies are compared based on the training data assembled from previous laboratory experiments. The best one is then chosen to design new experiment parameters, followed by measuring the corresponding properties of the newly synthesized samples. A previously unknown sample with ionic conductivity of 1.09 × 10$^{-3}$ S cm$^{-1}$ is discovered within several iterations. In order to further understand the mechanisms governing the high ionic conductivity of these samples, the resulting phase compositions and crystal structures are studied with X-ray diffraction, while the microstructures of sintered pellets are investigated by scanning electron microscopy. Our studies demonstrate the advantages of applying machine learning in designing experimental conditions by the synthesis of desired materials, which can effectively help researchers to reduce the number of required experiments

Wiring up pre-characterized single-photon emitters by laser lithography

Future quantum optical chips will likely be hybrid in nature and include many single-photon emitters, waveguides, filters, as well as single-photon detectors. Here, we introduce a scalable optical localization-selection-lithography procedure for wiring up a large number of single-photon emitters via polymeric photonic wire bonds in three dimensions. First, we localize and characterize nitrogen vacancies in nanodiamonds inside a solid photoresist exhibiting low background fluorescence. Next, without intermediate steps and using the same optical instrument, we perform aligned three-dimensional laser lithography. As a proof of concept, we design, fabricate, and characterize three-dimensional functional waveguide elements on an optical chip. Each element consists of one single-photon emitter centered in a crossed-arc waveguide configuration, allowing for integrated optical excitation and efficient background suppression at the same time

Establishment of a preclinical ovine screening model for the investigation of bone tissue engineering strategies in cancellous and cortical bone defects

Background New tissue engineering strategies for bone regeneration need to be investigated in a relevant preclinical large animal model before making the translation into human patients. Therefore, our interdisciplinary group established a simplified large animal screening model for intramembranous bone defect regeneration in cancellous and cortical bone. Methods Related to a well-established model of cancellous drill hole defect regeneration in sheep, both the proximal and distal epimetaphyseal regions of the femur and the humerus were used bilaterally for eight drill hole cancellous defects (Ø 6 mm, 15 mm depth). Several improvements of the surgical procedure and equipment for an easier harvest of samples were invented. For the inclusion of cortical defect regeneration, a total of eight unicortical diaphyseal drill holes (6 mm Ø) were placed in the proximal-lateral and distal-medial parts of the metacarpal (MC) and metatarsal (MT) diaphyseal bone bilaterally. Acting moments within a normal gait cycle in the musculoskeletal lower limb model were compared with the results of the biomechanical in vitro torsion test until failure to ensure a low accidental fracture risk of utilized bones (ANOVA, p < 0.05). The model was tested in vivo, using thirteen adult, female, black-face sheep (Ø 66 kg; ± 5 kg; age ≥ 2.5 years). In a two-step surgical procedure 16 drill holes were performed for the investigation of two different time points within one animal. Defects were left empty, augmented with autologous cancellous bone or soft bone graft substitutes. Results The in vitro tests confirmed this model a high comparability between drilled MC and MT bones and a high safety margin until fracture. The exclusion of one animal from the in vivo study, due to a spiral fracture of the left MC bone led to a tolerable failure rate of 8 %. Conclusions As a screening tool, promising biomaterials can be tested in this cancellous and cortical bone defect model prior to the application in a more complex treatment site

In-situ hot forging directed energy deposition-arc of CuAl8 alloy

Funding Information: Authors acknowledge the Portuguese Fundação para a Ciência e a Tecnologia ( FCT - MCTES ) for its financial support via the project UID/EMS/00667/2019 (UNIDEMI). VD acknowledges Portuguese Fundação para a Ciência e a Tecnologia ( FCT - MCTES ) for funding the PhD grant SFRH/BD/139454/2018 . TAR acknowledges Portuguese Fundação para a Ciência e a Tecnologia ( FCT - MCTES ) for funding the PhD grant SFRH/BD/144202/2019 . Funding of CENIMAT/i3N by national funds through the Portuguese Fundação para a Ciência e a Tecnologia, I.P., within the scope of Multiannual Financing of R&D Units , reference UIDB/50025/2020–2023 is also acknowledge. This activity has received funding from the European Institute of Innovation and Technology (EIT) Raw Materials through the project Smart WAAM: Microstructural Engineering and Integrated Non-Destructive Testing. This body of the European Union receives support from the European Union's Horizon 2020 research and innovation programme. Parts of this research were carried out at PETRA III at DESY, a member of the Helmholtz Association. The research leading to this result has been supported by the project CALIPSOplus under the Grant Agreement 730872 from the EU Framework Programme for Research and Innovation HORIZON 2020 . This project has received funding from the EU-H2020 research and innovation programme under grant agreement No 654360 having benefitted from the access provided by PETRA III at DESY in Hamburg, Germany within the framework of the NFFA-Europe Transnational Access Activity. The authors acknowledge support by OCAS NV and GUARENTEED via Joachim Antonissen. Funding Information: Authors acknowledge the Portuguese Fundação para a Ciência e a Tecnologia (FCT - MCTES) for its financial support via the project UID/EMS/00667/2019 (UNIDEMI). VD acknowledges Portuguese Fundação para a Ciência e a Tecnologia (FCT - MCTES) for funding the PhD grant SFRH/BD/139454/2018. TAR acknowledges Portuguese Fundação para a Ciência e a Tecnologia (FCT - MCTES) for funding the PhD grant SFRH/BD/144202/2019. Funding of CENIMAT/i3N by national funds through the Portuguese Fundação para a Ciência e a Tecnologia, I.P. within the scope of Multiannual Financing of R&D Units, reference UIDB/50025/2020–2023 is also acknowledge. This activity has received funding from the European Institute of Innovation and Technology (EIT) Raw Materials through the project Smart WAAM: Microstructural Engineering and Integrated Non-Destructive Testing. This body of the European Union receives support from the European Union's Horizon 2020 research and innovation programme. Parts of this research were carried out at PETRA III at DESY, a member of the Helmholtz Association. The research leading to this result has been supported by the project CALIPSOplus under the Grant Agreement 730872 from the EU Framework Programme for Research and Innovation HORIZON 2020. This project has received funding from the EU-H2020 research and innovation programme under grant agreement No 654360 having benefitted from the access provided by PETRA III at DESY in Hamburg, Germany within the framework of the NFFA-Europe Transnational Access Activity. The authors acknowledge support by OCAS NV and GUARENTEED via Joachim Antonissen. Remark: The supplementary material is temporarily available in the Drive folder here: https://drive.google.com/drive/folders/1SFFlhJlmL5p3IkQis8cB6UVWva3wozGi?usp=sharing. Publisher Copyright: © 2022 Elsevier B.V.CuAl8 alloy finds applications in industrial components, where a good anti-corrosion and anti-wearing properties are required. The alloy has a medium strength and a good toughness with an elongation to fracture at room temperature of about 40%. Additionally, it has a good electrical conductivity, though lower than that of pure Al or pure Cu. Despite these characteristics, additive manufacturing of the CuAl8 alloy was not yet reported. In this work, the direct energy deposition-arc (DED-arc) with and without in-situ hot forging was used to determine the microstructure evolution and mechanical properties. No internal defects were seen on the parts produced. Hot forging combined with DED-arc was seen to reduce and homogenize the grain size, improve mechanical strength and isotropy of mechanical properties. Moreover, the use of this novel DED-arc variant was seen to reduce the magnitude of residual stresses throughout the fabricated part. We highlight that this alloy can be processed by DED-arc, and the hot forging operation concomitant with the material deposition has beneficial effects on the microstructure refinement and homogenization.publishersversionpublishe