The immunopathology of thymic GVHD

The clinical success of allogeneic hematopoietic stem cell transplantation (HSCT) depends on the appropriate reconstitution of the host's immune system. While recovery of T-cell immunity may occur in transplant recipients via both thymus-dependent and thymus-independent pathways, the regeneration of a population of phenotypically naive T cells with a broad receptor repertoire relies entirely on the de novo generation of T-cells in the thymus. Preclinical models and clinical studies of allogeneic HSCT have identified the thymus as a target of graft-versus-host disease (GVHD), thus limiting T-cell regeneration. The present review focuses on recent insight into how GVHD affects thymic structure and function and how this knowledge may aid in the design of new strategies to improve T-cell reconstitution following allogeneic HSC

Development of a Cu-Sn based brazing system with a low brazing and a high remelting temperature

Objective of the project presented is the development of a joining process for hot working steel components at low brazing temperatures leading to a bond with a much higher remelting temperature. This basically is achieved by the use of a Cu-Sn melt spinning foil combined with a pure Cu foil. During brazing, the Sn content of the foil is decreased by diffusion of Sn into the additional Cu resulting in a homogenious joint with a increased remelting temperature of the filler metal. Within this project specimens were brazed and diffusion annealed in a vacuum furnace at 850 °C varying the processing times (0 - 10 h). The samples prepared were studied metallographically and diffusion profiles of Sn were recorded using EDX line scans. The results are discussed in view of further investigations and envisaged applications.German Ministry of Economic Affairs and EnergyIGF/IGF 18.706 N/DV

A universal platform for magnetostriction measurements in thin films

We present a universal nanomechanical sensing platform for the investigation of magnetostriction in thin films. It is based on a doubly-clamped silicon nitride nanobeam resonator covered with a thin magnetostrictive film. Changing the magnetization direction within the film plane by an applied magnetic field generates a magnetostrictive stress and thus changes the resonance frequency of the nanobeam. A measurement of the resulting resonance frequency shift, e.g. by optical interferometry, allows to quantitatively determine the magnetostriction constants of the thin film. We use this method to determine the magnetostriction constants of a 10nm thick polycrystalline cobalt film, showing very good agreement with literature values. The presented technique can be useful in particular for the precise measurement of magnetostriction in a variety of (conducting and insulating) thin films, which can be deposited by e.g. electron beam deposition, thermal evaporation or sputtering

A Composite of Polyether Ether Ketone and Silica-Coated Copper Particles for Creating Tailored Conductive Tracks via Laser Printing

Conventional substrates for optoelectronic systems include inorganic or organic carrier materials; however, these systems are typically subjected to environmentally harmful multistep processes to prepare printed circuit boards. To mitigate these issues, the present article reports a polyether ether ketone (PEEK)-based composite densely filled with copper microparticles, prepared using a simple, cost-effective, and sustainable synthesis method. The material exhibits high thermal conductivity but is electrically nonconductive prior to undergoing laser treatment. To prevent the composite from exhibiting electrical conductivity, the copper particles are coated with a thin silica layer through a sol–gel reaction. The thermal stability of PEEK and the Cu–PEEK composites with Cu contents of up to 70 vol%, which are prepared via heat melding, is investigated by thermogravimetric analysis, differential scanning calorimetry, and Fourier-transform infrared spectroscopy to clarify the manner in which copper affects the chemical structure of the polymer. The developed composite exhibits a significantly higher thermal conductivity than that of the unfilled PEEK polymer. This paper also describes the effects of laser treatment on the surface morphology. Overall, this study suggests that conductive tracks with low electrical resistance can be created on electrically insulating substrates with high thermal conductivity