Additive Manufacturing of Binary Ni–Ti Shape Memory Alloys Using Electron Beam Powder Bed Fusion: Functional Reversibility Through Minor Alloy Modification and Carbide Formation

Shape memory alloys (SMAs), such as Ni–Ti, are promising candidates for actuation and damping applications. Although processing of Ni–Ti bulk materials is challenging, well-established processing routes (i.e. casting, forging, wire drawing, laser cutting) enabled application in several niche applications, e.g. in the medical sector. Additive manufacturing, also referred to as 4D-printing in this case, is known to be highly interesting for the fabrication of SMAs in order to produce near-net-shaped actuators and dampers. The present study investigated the impact of electron beam powder bed fusion (PBF-EB/M) on the functional properties of C-rich Ni50.9Ti49.1 alloy. The results revealed a significant loss of Ni during PBF-EB/M processing. Process microstructure property relationships are discussed in view of the applied master alloy and powder processing route, i.e. vacuum induction-melting inert gas atomization (VIGA). Relatively high amounts of TiC, being already present in the master alloy and powder feedstock, are finely dispersed in the matrix upon PBF-EB/M. This leads to a local change in the chemical composition (depletion of Ti) and a pronounced shift of the transformation temperatures. Despite the high TiC content, superelastic testing revealed a good shape recovery and, thus, a negligible degradation in both, the as-built and the heat-treated state

Radiosensitization by BRAF inhibitor therapy—mechanism and frequency of toxicity in melanoma patients

This study shows radiosensitization by BRAF inhibitors in clinical practice and ex vivo by fluorescence in situ hybridization of chromosomal breaks. Nevertheless, radiotherapy with concomitant BRAF inhibitor therapy is feasible with an acceptable increase in toxicity. Vemurafenib is a more potent radiosensitizer than dabrafenib in both the patient study and the ex vivo experiment

A benchmark study for different numerical parameters and their impact on the calculated strain levels for a model part door outer

Abstract. To increase the accuracy of finite element simulations in daily practice the local German and Austrian Deep Drawing Research Groups of IDDRG founded a special Working Group in year 2000. The main objective of this group was the continuously ongoing study and discussion of numerical / material effects in simulation jobs and to work out possible solutions. As a first theme of this group the intensive study of small die radii and the possibility of detecting material failure in these critical forming positions was selected. The part itself is a fictional body panel outside in which the original door handle of the VW Golf A4 has been constructed, a typical position of possible material necking or rupture in the press shop. All conditions to do a successful simulation have been taken care of in advance, material data, boundary conditions, friction, FLC and others where determined for the two materials in investigation -a mild steel and a dual phase steel HXT500X. The results of the experiments have been used to design the descriptions of two different benchmark runs for the simulation. The simulations with different programs as well as with different parameters showed on one hand negligible and on the other hand parameters with strong impact on the result -thereby having a different impact on a possible material failure prediction

Replication and validation of higher order models demonstrated that a summary score for the EORTC QLQ-C30 is robust.

Objective: To further evaluate the higher-order measurement structure of the European Organisation for Research and Treatment of Cancer (EORTC) Quality of Life Questionnaire (QLQ-C30) questionnaire, with the aim of generating a summary score. Study design and setting: Using pretreatment QLQ-C30 data (N=3,282), we conducted confirmatory factor analyses to test seven previously evaluated higher-order models. We compared the summary score(s) derived from the best performing higher-order model with the original QLQ-C30 scale scores, using tumor stage, performance status and change over time (N=244) as grouping variables. Results: Whereas all models showed acceptable fit, we continued in the interest of parsimony with known-groups validity and responsiveness analyses using a summary score derived from the single higher-order factor model. The validity and responsiveness of this QLQ-C30 Summary Score was equal to, and in many cases superior to the original, underlying QLQ-C30 scale scores. Conclusion: Our results provide empirical support for a measurement model for the QLQ-C30 yielding a single summary score. The availability of this Summary Score can avoid problems with potential Type I errors that arise due to multiple testing when making comparisons based on the 15 outcomes generated by this questionnaire, and may reduce sample size requirements for HRQL studies using the QLQ-C30 questionnaire when an overall summary score is a relevant primary outcome

Numerical study on load-bearing capabilities of beam-like lattice structures with three different unit cells

The design and analysis of lattice structures manufactured using Additive Manufacturing (AM) technique is a new approach to create lightweight high-strength components. However, it is difficult for engineers to choose the proper unit cell for a certain function structure and loading case. In this paper, three beam-like lattice structures with triangular prism, square prism and hexagonal prism were designed, manufactured by SLM process using AlSi10Mg and tested. The mechanical performances of lattice structures with equal relative density, equal base area and height, and equal length for all unit cells were conducted by Finite Element Analysis (FEA). It was found that effective Young’s modulus is proportional to relative density, but with different affecting levels. When the lattice structures are designed with the same relative density or the same side lengths, the effective Young’s modulus of lattice structure with triangular prism exhibits the maximum value for both cases. When the lattice structures are designed with the same base areas for all unit cells, the effective Young’s modulus of lattice structures with square prism presents the maximum. FEA results also show that the maximum stress of lattice structures with triangular prisms in each comparison is at the lowest level and the stiffness-to-mass ratio remains at the maximum value, showing the overwhelming advantages in terms of mechanical strength. The excellent agreements between numerical results and experimental tests reveal the validity of FEA methods applied. The results in this work provide an explicit guideline to fabricate beam-like lattice structures with the best tensile and bending capabilities

Growth factors in multiple myeloma: a comprehensive analysis of their expression in tumor cells and bone marrow environment using Affymetrix microarrays

<p>Abstract</p> <p>Background</p> <p>Multiple myeloma (MM) is characterized by a strong dependence of the tumor cells on their microenvironment, which produces growth factors supporting survival and proliferation of myeloma cells (MMC). In the past few years, many myeloma growth factors (MGF) have been described in the literature. However, their relative importance and the nature of the cells producing MGF remain unidentified for many of them.</p> <p>Methods</p> <p>We have analysed the expression of 51 MGF and 36 MGF receptors (MGFR) using Affymetrix microarrays throughout normal plasma cell differentiation, in MMC and in cells from the bone marrow (BM) microenvironment (CD14, CD3, polymorphonuclear neutrophils, stromal cells and osteoclasts).</p> <p>Results</p> <p>4/51 MGF and 9/36 MGF-receptors genes were significantly overexpressed in plasmablasts (PPC) and BM plasma cell (BMPC) compared to B cells whereas 11 MGF and 11 MGFR genes were overexpressed in BMPC compared to PPC. 3 MGF genes (AREG, NRG3, Wnt5A) and none of the receptors were significantly overexpressed in MMC versus BMPC. Furthermore, 3/51 MGF genes were overexpressed in MMC compared to the the BM microenvironment whereas 22/51 MGF genes were overexpressed in one environment subpopulation compared to MMC.</p> <p>Conclusions</p> <p>Two major messages arise from this analysis 1) The majority of MGF genes is expressed by the bone marrow environment. 2) Several MGF and their receptors are overexpressed throughout normal plasma cell differentiation. This study provides an extensive and comparative analysis of MGF expression in plasma cell differentiation and in MM and gives new insights in the understanding of intercellular communication signals in MM.</p

Social and health epidemiology of immigrants in Germany: past, present and future

Razum O, Wenner J. Social and health epidemiology of immigrants in Germany: past, present and future. Public Health Reviews. 2016;37(1): 4.Germany has experienced different forms of immigration for many decades. At the end of and after the Second World War, refugees, displaced persons and German resettlers constituted the largest immigrant group. In the 1950s, labor migration started, followed by family reunification. There has been a constant migration of refugees and asylum seekers reaching peaks in the early 1990s as well as today. Epidemiological research has increasingly considered the health, and the access to health care, of immigrants and people with migration background. In this narrative review we discuss the current knowledge on health of immigrants in Germany. The paper is based on a selective literature research with a focus on studies using representative data from the health reporting system. Our review shows that immigrants in Germany do not suffer from different diseases than non-immigrants, but they differ in their risk for certain diseases, in the resources to cope with theses risk and regarding access to treatment. We also identified the need for differentiation within the immigrant population, considering among others social and legal status, country of origin and duration of stay. Though most of the studies acknowledge the need for differentiation, the lack of data currently rules out analyses accounting for the existing diversity and thus a full understanding of health inequalities related to migration to Germany