Mechanical Properties and Microstructure of Inconel 718 Lattice Structures Produced by Selective Laser Melting Process.

This article presents the results of an analysis regarding the microstructure, mechanical strength, and microhardness of two kinds of samples built through selective laser melting with Inconel 718, the most frequently used alloy in metal additive manufacturing due to its excellent mechanical properties. The sample geometry was made up of two types of lattice structures with spherical and hyperbolical stiffness elements. The goals of these studies are to determine how homogenization heat treatment influences the microhardness and the mechanical properties of the specimens and to identify the structure with the best mechanical properties. The analysis showed that heat treatment was beneficial because the regular dendritic structure disappears, the δ phase precipitates at the grain boundaries, and both the γ and γ″ phases dissolve. It has also been shown that the structures with hyperbolical stiffness elements have better compressive strength than the structures with the elliptical structures, with a 47.6% increase for the as-fabricated structures and an approximate 50% increase for the heat-treated structure.

Enhanced Cells Anchoring to Electrospun Hybrid Scaffolds With PHBV and HA Particles for Bone Tissue Regeneration.

Hybrid materials combining organic and inorganic compounds used as scaffolds are highly beneficial in bone regeneration. In this study, we successfully produced by blend electrospinning poly(3-hydroxybutyric acid-co-3-hydrovaleric acid) (PHBV) scaffolds enriched with hydroxyapatite (HA) particles to biomimic bone tissue for improved and faster regeneration processes. The morphology, fiber diameters, and composition of the scaffolds were investigated by scanning electron microscopy (SEM) techniques followed by focused ion beam (FIB) sectioning to verify HA particles integration with PHBV fibers. In vitro cell culture was performed for 7 days and followed with the cell proliferation test (CellTiter-Blue® Assay). Additionally, cell integration with the scaffold was visualized by confocal and SEM imaging. We developed a simple way of obtaining hybrid scaffolds by electrospinning PHBV solution with HA particles without any post-processing. The PHBV + HA scaffold enhanced cell proliferation and filopodia formation responsible for cell anchoring within the created 3D environment. The obtained results show the great potential in the development of hybrid scaffolds stimulating bone tissue regeneration.

Oxygen-Scavenging Multilayered Biopapers Containing Palladium Nanoparticles Obtained by the Electrospinning Coating Technique.

The main goal of this study was to obtain, for the first time, highly efficient water barrier and oxygen-scavenging multilayered electrospun biopaper coatings of biodegradable polymers over conventional cellulose paper, using the electrospinning coating technique. In order to do so, poly(3-hydroxybutyrate) (PHB) and polycaprolactone (PCL) polymer-containing palladium nanoparticles (PdNPs) were electrospun over paper, and the morphology, thermal properties, water vapor barrier, and oxygen absorption properties of nanocomposites and multilayers were investigated. In order to reduce the porosity, and to enhance the barrier properties and interlayer adhesion, the biopapers were annealed after electrospinning. A previous study showed that electrospun PHB-containing PdNP did show significant oxygen scavenging capacity, but this was strongly reduced after annealing, a process that is necessary to form a continuous film with the water barrier. The results in the current work indicate that the PdNP were better dispersed and distributed in the PCL matrix, as suggested by focus ion beam-scanning electron microscopy (FIB-SEM) experiments, and that the Pd enhanced, to some extent, the onset of PCL degradation. More importantly, the PCL/PdNP nanobiopaper exhibited much higher oxygen scavenging capacity than the homologous PHB/PdNP, due to most likely, the higher oxygen permeability of the PCL polymer and the somewhat higher dispersion of the Pd. The passive and active multilayered biopapers developed here may be of significant relevance to put forward the next generation of fully biodegradable barrier papers of interest in, for instance, food packaging.

Surface-Potential-Controlled Cell Proliferation and Collagen Mineralization on Electrospun Polyvinylidene Fluoride (PVDF) Fiber Scaffolds for Bone Regeneration.

This study represents the unique analysis of the electrospun scaffolds with the controlled and stable surface potential without any additional biochemical modifications for bone tissue regeneration. We controlled surface potential of polyvinylidene fluoride (PVDF) fibers with applied positive and negative voltage polarities during electrospinning, to obtain two types of scaffolds PVDF(+) and, PVDF(-). The cells' attachments to PVDF scaffolds were imaged in great details with advanced scanning electron microscopy (SEM) and 3D tomography based on focus ion beam (FIB-SEM). We presented the distinct variations in cells shapes and in filopodia and lamellipodia formation according to the surface potential of PVDF fibers that was verified with Kelvin probe force microscopy (KPFM). Notable, cells usually reach their maximum spread area through increased proliferation, suggesting the stronger adhesion, which was indeed double for PVDF(-) scaffolds having surface potential of -95 mV. Moreover, by tuning the surface potential of PVDF fibers, we were able to enhance collagen mineralization for possible use in bone regeneration. The scaffolds built of PVDF(-) fibers demonstrated the greater potential for bone regeneration than PVDF(+), showing after 7 days in osteoblasts culture produce well-mineralized osteoid required for bone nodules. The collagen mineralization was confirmed with energy dispersive X-ray spectroscopy (EDX) and Sirius Red staining, additionally the cells proliferation with fluorescence microscopy and Alamar Blue assays. The scaffolds made of PVDF fibers with the similar surface potential to the cell membranes promoting bone growth for next-generation tissue scaffolds, which are on a high demand in bone regenerative medicine.

Implementing an evidence-informed faculty development program.

OBJECTIVE: To establish an evidence-informed faculty development program. DESIGN: Survey derived from a needs-assessment tool. SETTING: Department of Academic Family Medicine at the University of Saskatchewan, which is geographically dispersed across the province. PARTICIPANTS: Full-time faculty members in the Department of Academic Family Medicine at the University of Saskatchewan. MAIN OUTCOME MEASURES: Creation of an evidence-informed faculty development program. RESULTS: The response rate was 77.3% (17 of 22). The data were stratified by 2 groups: faculty members with less than 5 years of experience and those with 5 or more years of experience. Those with less than 5 years of experience rated the following as their top priorities: teaching, developing scholarly activities, and career development. Those with 5 or more years of experience rated the following as their top priorities: administration and leadership, teaching, and information technology. Although there were differences in overall priorities, the 2 groups identified 17 out of 54 skills as important to faculty development. CONCLUSION: The results of the needs-assessment tool were used to shape a dynamic, evidence-informed faculty development program with full-time faculty in the Department of Academic Family Medicine at the University of Saskatchewan. Future programs will continue to be dynamic, faculty-centred, and evidence-informed.

Targeting success in heart failure: evidence-based management.

Heart failure (HF) is a common condition in primary care with 1% of the population self-reporting this condition. Mortality is substantial, approaching 40% to 50% over 5 years. Heart failure is a complex syndrome in which abnormal heart function results in, or increases the subsequent risk of, clinical symptoms and signs of low cardiac output or pulmonary or systemic congestion.¹ This article will present some practical tips for managing HF.²

The surgical management of degenerative lumbar spondylolisthesis: a systematic review.

STUDY DESIGN: Systematic review. OBJECTIVE: To identify whether there is an advantage to instrumented or noninstrumented spinal fusion over decompression alone for patients with degenerative lumbar spondylolisthesis. SUMMARY OF BACKGROUND DATA: The operative management of degenerative spondylolisthesis includes spinal decompression with or without instrumented or noninstrumented spinal fusion. Evidence on the operative management of degenerative spondylolisthesis is still divisive. METHODS: Relevant RCT and comparative observational studies between 1966 and June 2005 were identified. Abstracted outcomes included clinical outcome, reoperation rate, and solid fusion status. Analyses were separated into: 1) fusion versus decompression alone and 2) instrumented fusion versus noninstrumented fusion. RESULTS: Thirteen studies were included. The studies were generally of low methodologic quality. A satisfactory clinical outcome was significantly more likely with fusion than with decompression alone (relative risk, 1.40; 95% confidence interval, 1.04-1.89; P < 0.05). The use of adjunctive instrumentation significantly increased the probability of attaining solid fusion (relative risk, 1.37; 95% confidence interval, 1.07-1.75; P < 0.05), but no significant improvement in clinical outcome was recorded (relative risk, 1.19; 95% confidence interval, 0.92-1.54). There was a nonsignificant trend toward lower repeat operations with fusion compared with both decompression alone and instrumented fusion. CONCLUSION: Spinal fusion may lead to a better clinical outcome than decompression alone. No conclusion about the clinical benefit of instrumenting a spinal fusion could be made. However, there is moderate evidence that the use of instrumentation improves the chance of achieving solid fusion.