Two-component fibrous materials based on poly(3-hydroxybutyrate) (PHB, Tm = 160 °C) and poly(ε-caprolactone) (PCL, Tm = 60 °C) were successfully fabricated by dual-jet electrospinning of their separate spinning solutions. The desired alignment of the fibers that compose PHB/PCL mats was achieved by using three types of rotating collectors—drum (smooth), blade and grid. Additional fiber alignment in the direction of collector rotation was achieved by rotating at 2200 rpm. Moreover, the selected concentration of PCL spinning solution resulted in fibers with spindle-like defects along their length. Thus, “segment” sealing of the PHB (high-melting) fibers by the molten PCL (low-melting) fibers/defects sites was achieved after heating the PHB/PCL mats above the melting temperature (Tm) of PCL. The surface morphology, thermal behavior and mechanical properties of the PHB/PCL mats before and after thermal treatment were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, differential scanning calorimetry (DSC) and mechanical tests. The results indicated that regardless of the cutting direction of the specimens (0° or 90°), thermal treated PHB/PCL mats reveal enhanced mechanical properties. Therefore, this work provides an easily feasible route for the fabrication of electrospun PHB/PCL mats with tunable mechanical properties and improved performance.

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Background and Aims The global pandemic with SARS-CoV-2 virus and Covid-19 threatened hemodialysis patients as vulnerable category with high risk for fatal outcome. The aim of the study was to determine the prevalence and risk factors for mortality in hemodialysis (HD) patients with confirmed Covid-19. Method This study was retrospective, multicentric, and included all HD patients with positive PCR test for SARS-CoV-2 during the period of 10 months from March 1 – December 31/2020. The outcome of patients with positive PCR test for SARS CoV-2 was evaluated. The following clinical parameters were compared in two groups of patients (the deceased and alive): age, sex, hemodialysis vintage, type of vascular access, BMI, Hemoglobin, WBC, Platelets, CRP, LDH, D-dimer, s-albumin, radiological findings, smoking abuse, therapy with ACE and ARBs, presence of symptoms and comorbidities: hypertension (HTA), diabetes mellitus (DM), coronary artery disease (CAD), chronic pulmonary disease (CPD), dyslipidemia, atrial fibrillation (AFF), malignancy, treatment in hospital and intensive care unit (ICU) with oxygen support and mechanical ventilation, and anticoagulant therapy. Statistical analysis was performed by SPSS, continued variables with ANOVA and categorical variables with Pearson Chi- square test and logistic regression. Results Of total 631 hemodialysis patients during the period of 10 months 162 patients (113 M and 49 F) or 25,67% were with positive PCR test for SARS-CoV-2, they have had mean age 62,47±13,14 years and HD vintage 71,93±68,01 months. During the observed period 38 patients with Covid-19 (25 M and 13 F) deceased, that represents mortality of 23,45%, 8 patients deceased at home and 30 patients in hospital. The mortality in patients with age range 18-49 years was 8%, with 50-59 years 18,9%, with 60-69 years 22,2%, with 70-79 years 31,2% and in patients with ≥ 80 years was 50%. Clinical parameters showed that the deceased patients compared with alive patients have had statistically significant higher age (67,7±10,57 vs 60,85±13,46 years; p=0.004), biochemical findings WBC (9,13±4,07 vs 6,45±3,0; p<0.001), LDH (394±4,07 vs 294±143; p=0.032), D-dimer (3699±4,07 vs 2025±2628; p=0.041), lower s-albumin (25,03±4,0 vs 34,57±6,89; p<0.001), and less hospital days (9,87±12,15 vs 16,24±14,31; p=0.04). Regarding comorbidities the mortality in the deceased patients was significantly higher in patients with chronic pulmonary disease (CPD) in comparison to patients without CPD (56,3% vs 19,9%; p=0.001), and in patients with malignancy in comparison to patients without malignancy (57,1% vs 21,9%; p=0.032). The mortality in hospitalized patients was significantly higher in comparison to treated patients at home (25,8% vs 10,5%; p<0.001) and was significantly higher in patients treated in ICU in comparison to patients treated at hospital (40,7% vs 25%; p<0.001). By logistic regression model it was determined that presence of chronic pulmonary disease (HR=6,178; p=0.008), ICU treatment (HR=5,311; p=0.01) and malignancy (HR=16,766; p=0.01) were the most predictive risk factors for mortality. Conclusion Our study showed that mortality is high in HD patients with Covid-19 and amounts 23,45%, which is in accordance with other larger studies of ERACODA and ERA-EDTA registry regarding mortality of hemodialysis patients with Covid-19 (25% vs 20%). The mortality in HD patients with Covid-19 was associated with advanced age, high level of WBC, LDH and D-dimer, and low level of s-albumin. In contrast to general population, no association with gender, diabetes and cardiovascular disease, but significant association of mortality with presence of chronic pulmonary disease, malignancy, hospital and ICU treatment was found.