Inverse determination of the thermal contact conductance for an interface between a Co28Cr6Mo hip stem and a PMMA-based bone cement.

Traditional mechanical methods for implant and bone cement removal during total hip arthroplasty (THA) revision surgeries typically lead to surrounding tissue damage and increased risk of femoral fractures. Transcutaneous induction heating is a promising new removal approach as it causes softening of the thermoplastic bone cement, and thus prevents damage to the surrounding tissue during removal and increases stability post-revision. However, precise knowledge of the heat transfer between implant and bone cement is necessary to minimize the risk of thermal damage to surrounding tissues.

Load-bearing capacity of an experimental dental implant made of Nb-1Zr.

Although implants have undergone a remarkable development over the past decades, modern implants still show complications that make the improvement of materials necessary. The presented study investigates the load-bearing capacity of an experimental dental implant made of a niobium alloy (Nb1Zr) compared to identical implants made of Ti6Al4V using chewing simulation for artificial aging. Eight implants each with an experimental design were manufactured from Nb1Zr and Ti6Al4V.

Investigating mechanical deformation's role in cochlear implant durability.

Platinum and platinum-based alloys are used as the electrode material in cochlear implants because of the biocompatibility and the favorable electrochemical properties. Still, these implants can fail over time. The present study was conducted to shed light on the effects of microstructure on the electrochemical degradation of platinum.

Fracture Resistance of Repaired 5Y-PSZ Zirconia Crowns after Endodontic Access.

This study analyzed the fracture load before and after a chewing simulation of zirconia crowns that were trepanned and repaired using composite resin. Overall, 3 groups with 15 5Y-PSZ crowns in each group were tested. For group A, the fracture load of the unmodified crowns was evaluated.

In vivo investigation of open-pored magnesium scaffolds LAE442 with different coatings in an open wedge defect.

The magnesium alloy LAE442 showed promising results as a bone substitute in numerous studies in non-weight bearing bone defects. This study aimed to investigate the in vivo behavior of wedge-shaped open-pored LAE442 scaffolds modified with two different coatings (magnesium fluoride (MgF, group 1)) or magnesium fluoride/calcium phosphate (MgF/CaP, group 2)) in a partial weight-bearing rabbit tibia defect model. The implantation of the scaffolds was performed as an open wedge corrective osteotomy in the tibia of 40 rabbits and followed for observation periods of 6, 12, 24, and 36 weeks.

Investigations into Flux-Free Plasma Brazing of Aluminum in a Local XHV-Atmosphere.

As a lightweight construction material, aluminum plays a key role in weight reduction and, thus, sustainability in the transport industry. The brazing of aluminum and its alloys is impeded by the natural passivating oxide layer, which interferes with the brazing process. The presented study investigates the possibility of using a thermal silane-doped argon plasma to reduce this oxide layer in situ and thus eliminating the need to use hazardous chemical fluxes to enable high-quality brazing.

Efficacy of Inhaled N-Chlorotaurine in a Mouse Model of and Pneumonia.

N-chlorotaurine (NCT) can be used topically as a well-tolerated anti-infective at different body sites. The aim of this study was to investigate the efficacy of inhaled NCT in a mouse model of fungal pneumonia. Specific pathogen-free female C57BL/6JRj seven-week-old mice were immune-suppressed with cyclophosphamide.

Characterization of the Interface between Aluminum and Iron in Co-Extruded Semi-Finished Products.

Within the framework of the Collaborative Research Center 1153, we investigated novel process chains for the production of bulk components with different metals as joining partners. In the present study, the co-extrusion of coaxially reinforced hollow profiles was employed to manufacture semi-finished products for a subsequent die-forging process, which was then used for the manufacture of hybrid bearing bushings. The hybrid hollow profiles, made of the aluminum alloy EN AW-6082 paired with either the case-hardening steel 20MnCr5, the stainless steel X5CrNi18-10, or the rolling bearing steel 100Cr6, were produced by Lateral Angular Co-Extrusion.

Induction Heating in Underwater Wet Welding-Thermal Input, Microstructure and Diffusible Hydrogen Content.

Hydrogen-assisted cracking is a major challenge in underwater wet welding of high-strength steels with a carbon equivalent larger than 0.4 wt%. In dry welding processes, post-weld heat treatment can reduce the hardness in the heat-affected zone while simultaneously lowering the diffusible hydrogen concentration in the weldment.

Effect of pore size on tissue ingrowth and osteoconductivity in biodegradable Mg alloy scaffolds.

Magnesium has mechanical properties similar to those of bone and is being considered as a potential bone substitute. In the present study, two different pore sized scaffolds of the Mg alloy LAE442, coated with magnesium fluoride, were compared. The scaffolds had interconnecting pores of either 400 (p400) or 500 µm (p500).

Increased expression of GABA receptor subunits associated with tonic inhibition in patients with temporal lobe epilepsy.

Epilepsy animal models indicate pronounced changes in the expression and rearrangement of GABA receptor subunits in the hippocampus and in para-hippocampal areas, including widespread downregulation of the subunits α5 and δ, and upregulation of α4, subunits that mediate tonic inhibition of GABA. In this case-control study, we investigated changes in the expression of subunits α4, α5 and δ in hippocampal specimens of drug resistant temporal lobe epilepsy patients who underwent epilepsy surgery. Using hybridization, immunohistochemistry and α5-specific receptor autoradiography, we characterized expression of the receptor subunits in specimens from patients with and without Ammon's horn sclerosis compared to post-mortem controls.

Distal Pancreatic Resection with Splenectomy in the Rat: A Pancreatic Fistula Model to Investigate Postsurgical Damage?

Background: Postoperative pancreatic fistula (POPF) is a major complication in pancreatic surgery and can cause considerable postoperative morbidity. Advanced surgical-technical approaches to prevent POPF did not yield a substantial improvement. To investigate innovative treatments, experimental animal models of distal pancreatic resection and pancreaticoduodenectomy are of fundamental importance.

Development of a Laser Powder Bed Fusion Process Tailored for the Additive Manufacturing of High-Quality Components Made of the Commercial Magnesium Alloy WE43.

Additive manufacturing (AM) has become increasingly important over the last decade and the quality of the products generated with AM technology has strongly improved. The most common metals that are processed by AM techniques are steel, titanium (Ti) or aluminum (Al) alloys. However, the proportion of magnesium (Mg) in AM is still negligible, possibly due to the poor processability of Mg in comparison to other metals.

The Applicability of the Standard DIN EN ISO 3690 for the Analysis of Diffusible Hydrogen Content in Underwater Wet Welding.

The European standard ISO 3690 regulates the measurement of diffusible hydrogen in arc-welded metal. It was designed for different welding methods performed in dry atmosphere (20% humidity). Some details of the standard are not applicable for wet underwater welding.

Comparative immunopathogenesis in a murine model of inhalative infection with the mucormycetes Lichtheimia corymbifera and Rhizopus arrhizus.

Pathogenic mucormycetes induce diseases with considerable morbidity and mortality in immunocompromised patients. Virulence data comparing different Mucorales species and various underlying risk factors are limited. We therefore compared the pathogenesis of inhalative infection by Rhizopus (R.

Investigation of degraded bone substitutes made of magnesium alloy using scanning electron microscope and nanoindentation.

Degradable bone substitutes made of magnesium alloys are an alternative to biological bone grafts. The main advantage is that they can be manufactured location- and patient-specific. To develop and scale appropriate implants using computational models, knowledge about the mechanical properties and especially the change in the properties during the degradation process is essential.

Comparison of two pore sizes of LAE442 scaffolds and their effect on degradation and osseointegration behavior in the rabbit model.

The magnesium alloy LAE442 emerged as a possible bioresorbable bone substitute over a decade ago. In the present study, using the investment casting process, scaffolds of the Magnesium (Mg) alloy LAE442 with two different and defined pore sizes, which had on average a diameter of 400 μm (p400) and 500 μm (p500), were investigated to evaluate degradation and osseointegration in comparison to a ß-TCP control group. Open-pored scaffolds were implanted in both greater trochanter of rabbits.

Microstructure Formation in Cast TiZrHfCoNiCu and CoNiCuAlGaIn High Entropy Shape Memory Alloys: A Comparison.

The present study is dedicated to the microstructure characterization of the as-cast high entropy intermetallics that undergo a martensitic transformation, which is associated with the shape memory effect. It is shown that the TiZrHfCoNiCu system exhibits strong dendritic liquation, which leads to the formation of martensite crystals inside the dendrites. In contrast, in the CoNiCuAlGaIn system the dendritic liquation allows the martensite crystals to form only in interdendritic regions.

A simulation model for the degradation of magnesium-based bone implants.

The development of degradable bone implants, in particular made of metal materials, is an emerging field. The advantage of degradable implants is that they do not have to be removed later. In order to be able to develop and scale appropriate implants for different applications, it is necessary to know the change in mechanical properties of the implant during the degradation process in general and at different locations.

Fatigue behavior of As-built selective laser melted titanium scaffolds with sheet-based gyroid microarchitecture for bone tissue engineering.

Selective laser melting (SLM) has enabled the production of porous titanium structures with biological and mechanical properties that mimic bone for orthopedic applications. These porous structures have a reduced effective stiffness which leads to improved mechanotransduction between the implant and bone. Triply periodic minimal surfaces (TMPS), specifically the sheet-based gyroid structures, have improved compressive fatigue resistance due lack of stress concentrations.

Processing and coating of open-pored absorbable magnesium-based bone implants.

Large bone defects or fractures must be treated with an implant or transplant. Resorbable implants are attractive as these require only one surgery, whereas bone autografts, which can be cut off from the same person's hip, require more than one procedure. Moreover, porous structures promote the ingrowth of the patient's bone.

Crystallographic Structure Analysis of a Ti-Ta Thin Film Materials Library Fabricated by Combinatorial Magnetron Sputtering.

Ti-Ta thin films exhibit properties that are of interest for applications as microactuators and as biomedical implants. A Ti-Ta thin film materials library was deposited at T = 25 °C by magnetron sputtering employing the combinatorial approach, which led to a compositional range of TiTa to TiTa. Subsequent high-throughput characterization methods permitted a quick and comprehensive study of the crystallographic, microstructural, and morphological properties, which strongly depend on the chemical composition.

Zn-Li alloy after extrusion and drawing: Structural, mechanical characterization, and biodegradation in abdominal aorta of rat.

Zinc shows great promise as a bio-degradable metal. Our early in vivo investigations implanting pure zinc wires into the abdominal aorta of Sprague-Dawley rats revealed that metallic zinc does not promote restenotic responses and may suppress the activities of inflammatory and smooth muscle cells. However, the low tensile strength of zinc remains a major concern.

Impact of intraprosthetic drilling on the strength of the femoral stem in periprosthetic fractures: A finite element investigation.

Treatment of periprosthetic femur fractures after total hip arthroplasty remains a major challenge in orthopedic surgery. Recently, a novel surgical technique using intraprosthetic screw fixation has been suggested. The purpose of this study was to evaluate the influence of drilling the femoral hip stem on integrity and strength of the implant.