Fluorine-Free Hydrophobic Modification and Waterproof Breathable Properties of Electrospun Polyacrylonitrile Nanofibrous Membranes

Waterproof breathable functional membranes have broad application prospects in the field of outdoors textiles. The fluorine-containing microporous membranes of the mainstream functional products easily cause harm to the environment, and thus, the fluorine-free environmental nanofibrous membranes are an important development direction for functional membranes. In this subject, the electrospun polyacrylonitrile nanofibrous membranes were first hydrophobically modified by amino functional modified polysiloxane (AMP), followed by in situ cross-linking modified with 4, 4’-methyl diphenylene diisocyanate (MDI). The fluorine-free modification by AMP altered the surface of the membranes from hydrophilic to hydrophobic, and greatly improved the waterproof properties with the hydrostatic pressure reaching to 87.6 kPa. In addition, the formation of bonding points and the in situ preparation of polyuria through the reaction between the isocyanate in MDI and the amino group in AMP, could improve the mechanical properties effectively. When using AMP with the concentration of 1 wt% and MDI with the concentration of 2 wt%, the relatively good comprehensive performance was obtained with good water resistance (93.8 kPa), modest vapor permeability (4.7 kg m−2 d−1) and air permeability (12.7 mm/s). Based on these testing data, the modified nanofibrous membranes had excellent waterproof and breathable properties, which has future potential in outdoor sports apparel

Tailoring Water-Resistant and Breathable Performance of Polyacrylonitrile Nanofibrous Membranes Modified by Polydimethylsiloxane

The demand of water-resistant and breathable materials applied to a separation medium and protective garments is steadily increasing. Typical approaches to obtain these functional materials are based on hydrophobic agents and porous substrates with small fiber diameter, tiny pore, and high porosity. However, a fluorinated hydrophobic finishing agent usually employed in providing effective waterproofness is limited with respect to their environmental persistence and toxic potential. Herein, with the aim to keep a balance between the water-resistance and breathability as well as mechanical properties, we fabricate a novel fluoride-free functional membrane by electrospun polyacrylonitrile (PAN) nanofibers modified with polydimethylsiloxane (PDMS). As determined by morphological, DSC, and FT-IR analyses, the curing reaction of PDMS macromolecules formed an abundance of hydrophobic adhesive structures, which improved the waterproof performance dramatically and imparted relative good breathability at the same time. By systematically tuning the curing temperature as well as the concentration of PDMS, the modified PAN membranes with 4 wt % PDMS possessed good water-resistance (80.9 kPa), modest vapor permeability (12.5 kg m^–2 d^–1), and air permeability (9.9 mm s^–1). Compared with pristine PAN membranes, the modified membranes were endowed with enhanced tensile stress of 15.7 MPa. The good comprehensive performance of the as-prepared membranes suggested their potential applications in protective clothing, membrane distillation, self-cleaning materials, and other medical products. Furthermore, the proposed relationship between porous structure and waterproof/breathable property as one considerable principle is applicable to designing functional membranes with different levels of protective and comfortable performance

Environmentally Friendly and Breathable Fluorinated Polyurethane Fibrous Membranes Exhibiting Robust Waterproof Performance

Waterproof and breathable membranes that provide a high level of protection and comfort are promising core materials for meeting the pressing demand for future upscale protective clothing. However, creating such materials that exhibit environmental protection, high performance, and ease of fabrication has proven to be a great challenge. Herein, we report a novel strategy for synthesizing fluorinated polyurethane (C6FPU) containing short perfluorohexyl (-C₆F₁₃) chains and introduced it as hydrophobic agent into a polyurethane (PU) solution for one-step electrospinning. A plausible mechanism about the dynamic behavior of fluorinated chains with an increasing C6FPU concentration was proposed. Benefiting from the utilization of magnesium chloride (MgCl₂), the fibrous membranes had dramatically decreased maximum pore sizes. Consequently, the prepared PU/C6FPU/MgCl₂ fibrous membranes exhibited an excellent hydrostatic pressure of 104 kPa, a modest water vapor transmission rate of 11.5 kg m^–2 d^–1, and a desirable tensile strength of 12.4 MPa. The facile fabrication of PU/C6FPU/MgCl₂ waterproof and breathable membranes not only matches well with the tendency to be environmentally protective but also fully meets the requirements for high performance in extremely harsh environments

Prospective observational cohort study on grading the severity of postoperative complications in global surgery research

Background The Clavien–Dindo classification is perhaps the most widely used approach for reporting postoperative complications in clinical trials. This system classifies complication severity by the treatment provided. However, it is unclear whether the Clavien–Dindo system can be used internationally in studies across differing healthcare systems in high- (HICs) and low- and middle-income countries (LMICs). Methods This was a secondary analysis of the International Surgical Outcomes Study (ISOS), a prospective observational cohort study of elective surgery in adults. Data collection occurred over a 7-day period. Severity of complications was graded using Clavien–Dindo and the simpler ISOS grading (mild, moderate or severe, based on guided investigator judgement). Severity grading was compared using the intraclass correlation coefficient (ICC). Data are presented as frequencies and ICC values (with 95 per cent c.i.). The analysis was stratified by income status of the country, comparing HICs with LMICs. Results A total of 44 814 patients were recruited from 474 hospitals in 27 countries (19 HICs and 8 LMICs). Some 7508 patients (16·8 per cent) experienced at least one postoperative complication, equivalent to 11 664 complications in total. Using the ISOS classification, 5504 of 11 664 complications (47·2 per cent) were graded as mild, 4244 (36·4 per cent) as moderate and 1916 (16·4 per cent) as severe. Using Clavien–Dindo, 6781 of 11 664 complications (58·1 per cent) were graded as I or II, 1740 (14·9 per cent) as III, 2408 (20·6 per cent) as IV and 735 (6·3 per cent) as V. Agreement between classification systems was poor overall (ICC 0·41, 95 per cent c.i. 0·20 to 0·55), and in LMICs (ICC 0·23, 0·05 to 0·38) and HICs (ICC 0·46, 0·25 to 0·59). Conclusion Caution is recommended when using a treatment approach to grade complications in global surgery studies, as this may introduce bias unintentionally

Critical care admission following elective surgery was not associated with survival benefit: prospective analysis of data from 27 countries

This was an investigator initiated study funded by Nestle Health Sciences through an unrestricted research grant, and by a National Institute for Health Research (UK) Professorship held by RP. The study was sponsored by Queen Mary University of London

The surgical safety checklist and patient outcomes after surgery: a prospective observational cohort study, systematic review and meta-analysis

© 2017 British Journal of Anaesthesia Background: The surgical safety checklist is widely used to improve the quality of perioperative care. However, clinicians continue to debate the clinical effectiveness of this tool. Methods: Prospective analysis of data from the International Surgical Outcomes Study (ISOS), an international observational study of elective in-patient surgery, accompanied by a systematic review and meta-analysis of published literature. The exposure was surgical safety checklist use. The primary outcome was in-hospital mortality and the secondary outcome was postoperative complications. In the ISOS cohort, a multivariable multi-level generalized linear model was used to test associations. To further contextualise these findings, we included the results from the ISOS cohort in a meta-analysis. Results are reported as odds ratios (OR) with 95% confidence intervals. Results: We included 44 814 patients from 497 hospitals in 27 countries in the ISOS analysis. There were 40 245 (89.8%) patients exposed to the checklist, whilst 7508 (16.8%) sustained ≥1 postoperative complications and 207 (0.5%) died before hospital discharge. Checklist exposure was associated with reduced mortality [odds ratio (OR) 0.49 (0.32–0.77); P\u3c0.01], but no difference in complication rates [OR 1.02 (0.88–1.19); P=0.75]. In a systematic review, we screened 3732 records and identified 11 eligible studies of 453 292 patients including the ISOS cohort. Checklist exposure was associated with both reduced postoperative mortality [OR 0.75 (0.62–0.92); P\u3c0.01; I2=87%] and reduced complication rates [OR 0.73 (0.61–0.88); P\u3c0.01; I2=89%). Conclusions: Patients exposed to a surgical safety checklist experience better postoperative outcomes, but this could simply reflect wider quality of care in hospitals where checklist use is routine