Experimental and Statistical Analysis of the Effect of Heat Treatment on Surface Roughness and Mechanical Properties of Thin-Walled Samples Obtained by Selective Laser Melting from the Material AlSi10Mg.

Statistical analysis of mechanical properties of thin-walled samples (~500 microns) obtained by selective laser melting from AlSi10Mg material and subjected to heat treatment for 1 h at temperatures from 260 °C to 440 °C (step of aging temperature change 30 °C) has shown that the maximum strain hardening in the stretching diagram section from yield strength to tensile strength is achieved at the heat treatment temperature equal to 290 °C. At carrying out of correlation analysis, a statistically significant positive correlation between deformation corresponding to yield strength and the sum of heights of the largest protrusions and depths of the largest depressions of the surface roughness profile within the basic length of the sample (Rz) and the full height of the surface roughness profile (Rmax) was established. It was found that the reason for the correlation is the presence of cohesive states between the extreme values of the surface roughness profile that persist along the entire length of the specimen.

Assessment Effect of Nanometer-Sized Al2O3 Fillers in Polylactide on Fracture Probability of Filament and 3D Printed Samples by FDM.

In this paper, a mathematical model for the description of the failure probability of filament and fused deposition modeling (FDM)-printed products is considered. The model is based on the results of tensile tests of filament samples made of polyacrylonitrile butadiene styrene (ABS), polylactide (PLA), and composite PLA filled with alumina (Al2O3) as well after FDM-printed products of "spatula" type. The application of probabilistic methods of fracture analysis revealed that the main contribution to the reduction of fracture probability is made by the elastic and plastic stages of the fracture curve under static loading. Particle distribution analysis of Al2O3 combined with fracture probability analysis shows that particle size distributions on the order of 10-5 and 10-6 mm decrease the fracture probability of the sample, whereas uniform particle size distributions on the order of 10-1 and 10-2 mm do not change the distribution probability. The paper shows that uneven distribution of Al2O3 fillers in composite samples made using FDM printing technology leads to brittle fracture of the samples.

Surgical Treatment Efficacy of CSF-Venous Fistulas: Systematic Review.

BACKGROUND: Cerebrospinal fluid (CSF)-venous fistula presents a pathologic connection between spinal subarachnoid space and adjacent epidural vein or veins. It is one of the 3 main causes of spontaneous intracranial hypotension along with dural defects and meningeal diverticulum. We performed a systematic review of the literature and analyzed individual participants' data focusing on clinical outcomes after different treatment modalities of CSF-venous fistula. METHODS: Systematic review was conducted according to PRISMA recommendations. Literature search was performed in PubMed and Web of Science databases with following key phrases: "CSF-venous fistula", "Spontaneous intracranial hypotension". Overall, 97 articles were found during the initial search; 15 were included for the final analysis, with a total number of 137 patients. RESULTS: Epidural blood patch (EBP) was performed as a first-line treatment in 37.1% of patients in individual data group, often not combined with fibrin glue (61.5%). Either partial (69.2%) or no resolution (30.8%) of symptoms was achieved after EBP injection. Nerve root ligation was the most common method of exclusion of CSF-venous fistula. Complete resolution of symptoms was achieved in 69.0% of patients, in 21.4% it was partial and in 9.5% no regress was found. Endovascular treatment was described only in 1 study. CONCLUSIONS: Surgical ligation of fistula is a treatment of choice. In approximately 70% of patients complete long-term resolution of symptoms is achieved after surgery. Endovascular treatment and fibrin glue injections are prospective and evolving options, which require further investigation.

The relationship between global cardiac and regional left atrial sympathetic innervation and epicardial fat in patients with atrial fibrillation.

AIM: To investigate the relationship between epicardial adipose tissue (EAT) volume and distribution and the parameters of global cardiac and regional left atrial (LA) sympathetic activity in patients with atrial fibrillation (AF). METHODS AND RESULTS: The data of the 45 consecutive patients scheduled for an index catheter ablation (CA) for AF were analyzed. Total and peri-atrial EAT volumes were measured by cardiac CT. Parameters of global cardiac sympathetic activity and discrete sympathetic regions around LA were assessed by 123I-mIBG SPECT/CT. The patients were followed up for AF recurrences assessment during 12 months after CA. A total of 133 (mean per patient 2.96 ± 1.07) discrete 123I-mIBG uptake areas (DUAs), corresponding to typical anatomical locations of LA ganglionated plexi (GP), were identified. Peri-atrial EAT volume was associated with the number of DUAs (regression estimate, 5.1 [95% CI, 0.3-9.9], p = 0.03). There was no statistically significant association between either total or peri-atrial EAT volumes and risks of AF recurrence. The washout rate (WR) was associated with reduced risk of AF recurrence (HR = 0.95; 95% CI 0.92-0.99; p = 0.01), while left ventricular (LV) myocardium 123I-mIBG summed defect score (SDS) was linked to increased hazards of AF recurrence (HR = 1.04; 95% CI 1.01-1.08; p = 0.03). CONCLUSION: Peri-atrial EAT volume is associated with regions of sympathetic activity corresponding to typical anatomical locations of LA GP. The WR was associated with reduced risk of AF recurrence while LV myocardial SDS was linked to increased hazards of AF recurrence.