Engraving Polyamide Layers by In Situ Self-Etchable CaCO3 Nanoparticles Enhances Separation Properties and Antifouling Performance of Reverse Osmosis Membranes.

Nanovoids within a polyamide layer play an important role in the separation performance of thin-film composite (TFC) reverse osmosis (RO) membranes. To form more extensive nanovoids for enhanced performance, one commonly used method is to incorporate sacrificial nanofillers in the polyamide layer during the exothermic interfacial polymerization (IP) reaction, followed by some post-etching processes. However, these post-treatments could harm the membrane integrity, thereby leading to reduced selectivity. In this study, we applied in situ self-etchable sacrificial nanofillers by taking advantage of the strong acid and heat generated in IP. CaCO3 nanoparticles (nCaCO3) were used as the model nanofillers, which can be in situ etched by reacting with H+ to leave void nanostructures behind. This reaction can further degas CO2 nanobubbles assisted by heat in IP to form more nanovoids in the polyamide layer. These nanovoids can facilitate water transport by enlarging the effective surface filtration area of the polyamide and reducing hydraulic resistance to significantly enhance water permeance. The correlations between the nanovoid properties and membrane performance were systematically analyzed. We further demonstrate that the nCaCO3-tailored membrane can improve membrane antifouling propensity and rejections to boron and As(III) compared with the control. This study investigated a novel strategy of applying self-etchable gas precursors to engrave the polyamide layer for enhanced membrane performance, which provides new insights into the design and synthesis of TFC membranes.

Unveiling the Growth of Polyamide Nanofilms at Water/Organic Free Interfaces: Toward Enhanced Water/Salt Selectivity.

The permeance and selectivity of a reverse osmosis (RO) membrane are governed by its ultrathin polyamide film, yet the growth of this critical film during interfacial polymerization (IP) has not been fully understood. This study investigates the evolution of a polyamide nanofilm at the aqueous/organic interface over time. Despite its thickness remaining largely constant (∼15 nm) for the IP reaction time ranging from 0.5 to 60 min, the density of the polyamide nanofilm increased from 1.25 to 1.36 g cm-3 due to the continued reaction between diffused m-phenylenediamine and dangling acyl chloride groups within the formed polyamide film. This continued growth of the polyamide nanofilm led to a simultaneous increase in its crosslinking degree (from 50.1 to 94.3%) and the healing of nanosized defects, resulting in a greatly enhanced rejection of 99.2% for NaCl without sacrificing water permeance. Using humic acid as a molecular probe for sealing membrane defects, the relative contributions of the increased crosslinking and reduced defects toward better membrane selectivity were resolved, which supports our conceptual model involving both enhanced size exclusion and healed defects. The fundamental insights into the growth mechanisms and the structure-property relationship of the polyamide nanofilm provide crucial guidance for the further development and optimization of high-performance RO membranes.

NaHCO3 addition enhances water permeance and Ca/haloacetic acids selectivity of nanofiltration membranes for drinking water treatment.

The existence of disinfection by-products such as haloacetic acids (HAAs) in drinking water severely threatens water safety and public health. Nanofiltration (NF) is a promising strategy to remove HAAs for clean water production. However, NF often possesses overhigh rejection of essential minerals such as calcium. Herein, we developed highly selective NF membranes with tailored surface charge and pore size for efficient rejection of HAAs and high passage of minerals. The NF membranes were fabricated through interfacial polymerization (IP) with NaHCO3 as an additive. The NaHCO3-tailored NF membranes exhibited high water permeance up to ∼24.0 L m - 2 h - 1 bar-1 (more than doubled compared with the control membrane) thanks to the formation of stripe-like features and enlarged pore size. Meanwhile, the tailored membranes showed enhanced negative charge, which benefitted their rejection of HAAs and passage of Ca and Mg. The higher rejection of HAAs (e.g., > 90%) with the lower rejection of minerals (e.g., < 30% for Ca) allowed the NF membranes to achieve higher minerals/HAAs selectivity, which was significantly higher than those of commercially available NF membranes. The simultaneously enhanced membrane performance and higher minerals/HAAs selectivity would greatly boost water production efficiency and water quality. Our findings provide a novel insight to tailor the minerals/micropollutants selectivity of NF membranes for highly selective separation in membrane-based water treatment.

A Randomized Trial Comparing the NeoVas Sirolimus-Eluting Bioresorbable Scaffold and Metallic Everolimus-Eluting Stents.

OBJECTIVES: The authors sought to evaluate the safety and effectiveness of the NeoVas bioresorbable scaffold (BRS) compared with metallic drug-eluting stents. BACKGROUND: BRS have the potential to improve very late outcomes compared with metallic drug-eluting stents, but some BRS have been associated with increased rates of device thrombosis before complete bioresorption. NeoVas is a new poly-l-lactic acid BRS that elutes sirolimus from a poly-D, l-lactide coating. METHODS: Eligible patients with a single de novo native coronary artery lesion with a reference vessel diameter 2.5 to 3.75 mm and a lesion length ≤20 mm were randomized 1:1 to NeoVas BRS versus cobalt-chromium everolimus-eluting stents (CoCr-EES). Angiographic follow-up was performed in all patients at 1 year. The primary endpoint was angiographic in-segment late loss (LL), and the major secondary endpoint was the rate of angina. Baseline and follow-up optical coherence tomography and fractional flow reserve were performed in a pre-specified subgroup of patients. RESULTS: The authors randomized 560 patients at 32 centers to treatment with NeoVas (n = 278) versus CoCr-EES (n = 282). One-year in-segment LL with NeoVas and CoCr-EES were 0.14 ± 0.36 mm versus 0.11 ± 0.34 mm (difference 0.03 mm; upper 1-sided 97.5% confidence interval 0.09 mm; pnoninferiority < 0.0001; psuperiority = 0.36). Clinical outcomes at 1 year were similar in the 2 groups, as were the rates of recurrent angina (27.9% vs. 32.1%; p = 0.26). Optical coherence tomography at 1 year demonstrated a higher proportion of covered struts (98.7% vs. 96.2%; p < 0.001), less strut malapposition (0% vs. 0.6%; p <0.001), and a smaller minimal lumen area (4.71 ± 1.64 vs. 6.00 ± 2.15 mm2; p < 0.001) with NeoVas compared with CoCr-EES respectively, with nonsignificant differences in fractional flow reserve (0.89 ± 0.08 vs. 0.91 ± 0.06; p = 0.07). CONCLUSIONS: The NeoVas BRS was noninferior to CoCr-EES for the primary endpoint of 1-year angiographic in-segment LL, and resulted in comparable 1-year clinical outcomes, including recurrent angina. (NeoVas Bioresorbable Coronary Scaffold Randomized Controlled Trial; NCT02305485).

Herpes simplex virus 1 interaction with Toll-like receptor 2 contributes to lethal encephalitis.

Human neonates infected with herpes simplex virus 1 (HSV-1) develop one of three distinct patterns of infection: (i) infection limited to the skin, eye or mouth; (ii) infection of the CNS; or (iii) disseminated infection. The disseminated form usually involves the liver, adrenal gland, and lung, and resembles the clinical picture of bacterial sepsis. This spectrum of symptoms in HSV-1-infected neonates suggests that inflammatory cytokines play a significant role in the pathogenesis of the disease. Recent studies suggest that the Toll-like receptors (TLRs) may play an important role in the induction of inflammatory cytokines in response to viruses. TLRs are mammalian homologues of Toll, a Drosophila protein that is essential for host defense against infection. Engagement of TLRs by bacterial, viral, or fungal components leads to the production and release of cytokines and other antimicrobial products. Here, we demonstrate that TLR2 mediates the inflammatory cytokine response to HSV-1 by using both transfected cell lines and knockout mice. Studies of infected mice revealed that HSV-1 induced a blunted cytokine response in TLR2(-/-) mice. Brain levels of monocyte chemoattractant protein 1 chemokine were significantly lower in TLR2(-/-) mice than in either wild-type or TLR4(-/-) mice. TLR2(-/-) mice had reduced mortality compared with wild-type mice. The differences between TLR2(-/-) mice and both wild-type and TLR4(-/-) mice in the induction of monocyte chemoattractant protein 1, brain inflammation, or mortality could not be accounted for on the basis of virus levels. Thus, these studies suggest the TLR2-mediated cytokine response to HSV-1 is detrimental to the host.