Post-Processing Treatment Impact on Mechanical Properties of SLM Deposited Ti-6Al-4 V Porous Structure for Biomedical Application

Additive manufacturing technologies allow producing a regular three-dimensional mesh of interconnected struts that form an open-cell porous structure. Regular porous structures have been used in the orthopedic industry due to outstanding bone anchoring. The aim of the study was to determine how the postprocessing influences the mechanical properties of porous structures made of titanium alloy CL 41TI ELI. The effect of hot isostatic pressing (HIP) as a method of increasing microstructural integrity was investigated here. The influence of surface etching (SE) technique, which was applied to the porous structure for cleaning unmelted titanium powder particles on the surface of connectors from the inner surfaces of a porous structure, was examined in this study. Mechanical properties were investigated by means of compression tests. The results point out that HIP has a minor effect on the mechanical behavior of considered porous structures. The SE is an effective method to clean the surface of a porous structure, which is very important in the case of biomedical applications when loose powder can cause serious health problems. Another effect of the SE is also the strut thickness reduction. Reducing strut thickness of a porous structure with the surface etching decreases its stiffness to the same extent as predicted by the relative density theoretical model but did not result in structural damage.     

The Impact of Leg Length Discrepancy on Clinical Outcome of Total Hip Arthroplasty: Comparison of Four Measurement Methods

In a single-surgeon series of 119 patients with unilateral primary uncemented total hip arthroplasty, four leg-length discrepancy measurement methods (absolute, relative, trochanteric, standardized-trochanteric) were analyzed for their impact on WOMAC score, Oxford Hip Score and self-perceived leg-length discrepancy. After adjustment for age, gender and BMI, postoperative WOMAC scores correlated only with clinical absolute measurements of leg elongation (P = 0.05). Self-perceived leg-length discrepancy corresponded best to the clinically measured relative leg-length discrepancy (11 mm perceived vs. 7 mm unperceived; P = 0.04) while there was no significant correspondence with radiographic measurements or leg elongation magnitudes. Within the < 10 mm range of mean postoperative leg length discrepancy in the studied series, its impact on the overall clinical satisfaction was detectable but not considerable.     

Non-surgical management of early knee osteoarthritis

Conservative approach is usually the first choice for the management of the knee degeneration processes, especially in the phase of the disease recognized as early osteoarthritis (OA) with no clear lesions or associated abnormalities requiring to be addressed surgically. A wide spectrum of treatments is available, from non-pharmacological modalities to dietary supplements and pharmacological therapies, as well as minimally invasive procedures involving injections of various substances aiming to restore joint homeostasis and provide clinical improvement and possibly a disease-modifying effect. Numerous pharmaceuticals have been proposed, but since no therapy has shown all the characteristic of an ideal treatment, and side effects have been reported at both systemic and local level, the use of pharmacological agents should be considered with caution by assessing the risk/benefit ratio of the drugs prescribed. Both patients and physicians should have realistic outcome goals in pharmacological treatment, which should be considered together with other conservative measures. A combination of these therapeutic options is a more preferable scenario, in particular considering the evidence available for non-pharmacological management. In fact, exercise is an effective conservative approach, even if long-term effectiveness and optimal dose and administration modalities still need to be clarified. Finally, physical therapies are emerging as viable treatment options, and novel biological approaches are under study. Further studies to increase the limited medical evidence on conservative treatments, optimizing results, application modalities, indications, and focusing on early OA will be necessary in the future.     

Vasa nervorum of epicardial nerves and valves of small veins investigated in porcine heart by two types of vascular injections

The morphology of the vascular supply of peripheral branches of cardiac nerves has not been systematically described until now. The aim of this study was to describe the architectonics of the vasa nervorum of epicardial nerves in porcine hearts by using two injection techniques. Twenty-three hearts from young healthy pigs were used. In 10 hearts India ink solution was injected into the origin of the anterior interventricular branch. In another 10 hearts India ink solution was injected retrogradely through the coronary sinus. The hearts were then analyzed using a magnifying glass and light microscopy. The arterial injection showed the entirety of the rich venous components of the vasa nervorum, which often consisted of paired veins accompanying the epicardial nerves. The thickness of the nerves ranged from 50 to 815 μm. The vasa nervorum drained into larger subepicardial veins. In seven of the hearts prepared with venous injections the vasa nervorum of epicardial nerves were visualized in the same detail as in the arterial preparations and India ink solution filled the right ventricle via the smallest cardiac veins. The histological analysis of these seven hearts showed complete dehiscence and functional insufficiency of small and larger veins valves. In the other three hearts prepared with venous injections the valves were competent, which prevented retrograde filling of larger and smaller veins. The results obtained expand the current knowledge on epicardial nerves vasa nervorum and provide anatomical evidence behind the mechanism of retrograde application of cardioplegic solutions in cardiac surgery.     

Experimental and Numerical Analysis of High-Temperature Superconducting Tapes Modified by Composite Thermal Stabilization Subjected to Thermomechanical Loading

The strain behavior of SiC/Stycast 2850 FT composites under thermomechanical loading using a finite element analysis (FEA) was studied. These composites can serve as thermal stabilizers of high-temperature superconducting (HTS) tapes during limitation event in resistive superconducting fault current limiter (R-SCFCL) applications. For this purpose, the thermomechanical properties of four composite systems with different filler content were studied experimentally. The FEA was calculated using an ANSYS software and it delivered useful information about the strain distribution in the composite coating, as well as in particular layers of the modified HTS tapes. The tapes were subjected to bending over a 25 cm core, cooled in a liquid nitrogen (LN2) bath, and finally, quenched from this temperature to various temperatures up to 150 °C for a very short time, simulating real limitation conditions. The outputs from simulations were also correlated with the experiments. The most promising of all investigated systems was SB11-SiC20 composite in form of 100 µm thick coating, withstanding a temperature change from LN2 up to 120 °C.     

Elicitation of neurological knowledge with argument-based machine learning

ObjectiveThe paper describes the use of expert's knowledge in practice and the efficiency of a recently developed technique called argument-based machine learning (ABML) in the knowledge elicitation process. We are developing a neurological decision support system to help the neurologists differentiate between three types of tremors: Parkinsonian, essential, and mixed tremor (comorbidity). The system is intended to act as a second opinion for the neurologists, and most importantly to help them reduce the number of patients in the “gray area” that require a very costly further examination (DaTSCAN). We strive to elicit comprehensible and medically meaningful knowledge in such a way that it does not come at the cost of diagnostic accuracy.Materials and methodsTo alleviate the difficult problem of knowledge elicitation from data and domain experts, we used ABML. ABML guides the expert to explain critical special cases which cannot be handled automatically by machine learning. This very efficiently reduces the expert's workload, and combines expert's knowledge with learning data. 122 patients were enrolled into the study.ResultsThe classification accuracy of the final model was 91%. Equally important, the initial and the final models were also evaluated for their comprehensibility by the neurologists. All 13 rules of the final model were deemed as appropriate to be able to support its decisions with good explanations.ConclusionThe paper demonstrates ABML's advantage in combining machine learning and expert knowledge. The accuracy of the system is very high with respect to the current state-of-the-art in clinical practice, and the system's knowledge base is assessed to be very consistent from a medical point of view. This opens up the possibility to use the system also as a teaching tool.     

Genetic variation in potential Giardia vaccine candidates cyst wall protein 2 and α1-giardin

Parasitology Research - Giardia is a prevalent intestinal parasitic infection. The trophozoite structural protein a1-giardin (a1-g) and the cyst protein cyst wall protein 2 (CWP2) have shown...