Playing with Low Amounts of Expanded Graphite for Melt-Processed Polyamide and Copolyester Nanocomposites to Achieve Control of Mechanical, Tribological, Thermal and Dielectric Properties.

Polyamide 11 (PA11) and copolyester (TPC-E) were compounded through melt extrusion with low levels (below 10%) of expanded graphite (EG), aiming at the manufacturing of a thermally and electrically conductive composite resistant to friction and with acceptable mechanical properties. Thermal characterisation showed that the EG presence had no influence on the onset degradation temperature or melting temperature. While the specific density of the produced composite materials increased linearly with increasing levels of EG, the tensile modulus and flexural modulus showed a significant increase already at the introduction of 1 wt% EG.

Accuracy of intraoperative bone registration and stereotactic boundary reconstruction during total knee arthroplasty surgery.

Background: The intraoperative registration of the bones play a crucial role in image-based computer-assisted knee arthroplasty to achieve accurate implant placement and to create reliable stereotactic bone boundaries for robot-assisted surgical systems.

Method: This study assessed the intraoperative registration accuracy on six intact fresh frozen cadavers.

Results: Rotational errors around the mechanical axis were the largest, with a standard deviation of 1.

Setting the Optimal Laser Power for Sustainable Powder Bed Fusion Processing of Elastomeric Polyesters: A Combined Experimental and Theoretical Study.

Additive manufacturing (AM) of polymeric materials offers many benefits, from rapid prototyping to the production of end-use material parts. Powder bed fusion (PBF), more specifically selective laser sintering (SLS), is a very promising AM technology. However, up until now, most SLS research has been directed toward polyamide powders.

An improved method for assessing the technical accuracy of optical tracking systems for orthopaedic surgical navigation.

Background: Optical tracking systems (OTSs) are essential components of many modern computer assisted orthopaedic surgery (CAOS) systems but patient movement is often neglected in the evaluation of the accuracy. The aim of this study was to develop a representative test to assess the accuracy of OTSs including patient movement and demonstrate the effect of pointer design and OTS choice.

Method: A mobile phantom with dynamic reference base (DRB) attached was designed and constructed.

Abrasive Sensitivity of Martensitic and a Multi-Phase Steels under Different Abrasive Conditions.

The wear behaviour of two martensitic and one multiphase steel targeted for abrasion and erosion applications in agriculture and mining industry were investigated in three abrasive test systems with different complexity. Scratch tests were performed with different indenter radii, shapes, and loads. The material behaviour was also investigated in multi-asperity contact systems.

Soft-tissue penetration of the oscillating saw during tibial resection in total knee arthroplasty.

Aims: Inadvertent soft tissue damage caused by the oscillating saw during total knee arthroplasty (TKA) occurs when the sawblade passes beyond the bony boundaries into the soft tissue. The primary objective of this study is to assess the risk of inadvertent soft tissue damage during jig-based TKA by evaluating the excursion of the oscillating saw past the bony boundaries. The second objective is the investigation of the relation between this excursion and the surgeon's experience level.

Processing Analysis of Nanoparticle Filled PTFE: Restrictions and Limitations of High Temperature Production.

In this research work, unfilled and monofilled polytetrafluoroethylene (PTFE) were investigated. The applied fillers were graphene, alumina (AlO), boehmite alumina (BA80) and hydrotalcite (MG70). Graphene and AlO are already known in the literature as potential fillers of PTFE, while BA80 and MG70 are novel fillers in PTFE.

Thermal, Viscoelastic, Mechanical and Wear Behaviour of Nanoparticle Filled Polytetrafluoroethylene: A Comparison.

In this research work, unfilled and mono-filled polytetrafluoroethylene (PTFE) materials were developed and characterised by physical, thermal, viscoelastic, mechanical, and wear analysis. The applied fillers were graphene, alumina (AlO), boehmite alumina (BA80), and hydrotalcite (MG70) in 0.25/1/4/8 and 16 wt % filler content.

Fabrication of Microporous Coatings on Titanium Implants with Improved Mechanical, Antibacterial, and Cell-Interactive Properties.

The success of an orthopedic implant therapy depends on successful bone integration and the prevention of microbial infections. In this work, plasma electrolytic oxidation (PEO) was performed to deposit TiO coatings enriched with Ca, P, and Ag on titanium to improve its surface properties and antibacterial efficacy while maintaining normal biological functions and thus to enhance the performance of orthopedic implants. After PEO treatment, the surface of Ti was converted to anatase and rutile TiO, hydroxyapatite, and calcium titanate phases.

A comparison of propofol-to-BIS post-operative intensive care sedation by means of target controlled infusion, Bayesian-based and predictive control methods: an observational, open-label pilot study.

Purpose: We evaluated the feasibility and robustness of three methods for propofol-to-bispectral index (BIS) post-operative intensive care sedation, a manually-adapted target controlled infusion protocol (HUMAN), a computer-controlled predictive control strategy (EPSAC) and a computer-controlled Bayesian rule-based optimized control strategy (BAYES).

Methods: Thirty-six patients undergoing short lasting sedation following cardiac surgery were included to receive propofol to maintain a BIS between 40 and 60. Robustness of control for all groups was analysed using prediction error and spectrographic analysis.

Online Wear Detection Using High-Speed Imaging.

In this paper, the change detection of a fast turning specimen is studied at micro-level, whereas the images are acquired without stopping the rotation. In the beginning of the experiment, the imaging system is focused on the surface of the specimen. By starting the rotation of the specimen, the diameter of the specimen changes due to wear, which results in de-focusing of the imaging system.

The effect of trochlear dysplasia on patellofemoral biomechanics: a cadaveric study with simulated trochlear deformities.

Background: Trochlear dysplasia appears in different geometrical variations. The Dejour classification is widely used to grade the severity of trochlear dysplasia and to decide on treatment.

Purpose: To investigate the effect of trochlear dysplasia on patellofemoral biomechanics and to determine if different types of trochlear dysplasia have different effects on patellofemoral biomechanics.

The use of cyanoacrylate sealant as simple mesh fixation in laparoscopic ventral hernia repair: a large animal evaluation.

Purpose: The use of glue as mesh fixation in laparoscopic ventral hernia repair (LVHR) significantly reduces fixation associated morbidity. This experiment evaluates the intraperitoneal use of synthetic glue as single mesh fixation.

Methods: A total of 21 sheep were operated using a hernia model with two fascial defects of 2 cm(2) at the linea alba.

By-products resulting from lignocellulose pretreatment and their inhibitory effect on fermentations for (bio)chemicals and fuels.

Lignocellulose might become an important feedstock for the future development of the biobased economy. Although up to 75 % of the lignocellulose dry weight consists of sugar, it is present in a polymerized state and cannot be used directly in most fermentation processes for the production of chemicals and fuels. Several methods have been developed to depolymerize the sugars present in lignocellulose, making the sugars available for fermentation.

The use of rapid prototyped implants to simulate knee joint abnormalities for in vitro testing: a validation study with replica implants of the native trochlea.

To investigate the biomechanical effect of skeletal knee joint abnormalities, the authors propose to implant pathologically shaped rapid prototyped implants in cadaver knee specimens. This new method was validated by replacing the native trochlea by a replica implant on four cadaver knees with the aid of cadaver-specific guiding instruments. The accuracy of the guiding instruments was assessed by measuring the rotational errors of the cutting planes (on average 3.

Pilot validation study on a quasi-static weight-bearing knee rig.

This article presents a pilot study on a quasi-static knee rig designed to investigate the influence of pathologies and surgical interventions on the patellofemoral kinetics of cadaveric knees. The knee rig allows cadaveric knees to flex and extend under a simulated body weight by transmitting a force to the quadriceps tendon. During the squat simulation, the ground reaction force stays within physiological values.

Patellofemoral contact pressures.

A test rig for studying the biomechanical behaviour of post-mortem human knees is built. For loading the quadriceps tendon a special clamping device is constructed, so the forces up to 3000 N could easily be transferred to the tendon. Several post-mortem human knees used in this study are tested to collect data about the general biomechanics of knee joint during squatting.

Magnetic resonance imaging of extrapontine lesions in central pontine myelinolysis.

A rare case of central pontine myelinolysis and associated extrapontine myelinolysis is presented. The MR findings confirmed the observations reported in recent papers.

Instrumentation of a gravity feed extruder and the influence of the composition of binary and ternary mixtures on the extrusion forces.

A gravity feed extruder was adapted to monitor the extrusion forces, the temperature during processing and the rotational speed of the extruding cylinders. The extruder was used to evaluate the influence of particle size of insoluble material and of product solubility on the extrusion forces. Microcrystalline cellulose, dicalcium phosphate dihydrate and different lactoses were used as model compounds.

Atherosclerosic dissection of the cervical internal carotid artery--a case report.

Atherosclerosis as a cause of spontaneous dissection in the cervical internal carotid arteries has been described in only a few cases. The authors present a surgically and pathologically proven case of dissection on the base of atherosclerosis of the cervical internal carotid artery. A resection of the pathologic segment with arterial reconstruction by direct anastomosis with a venous patch graft was performed.