Photoswitchable semiconducting polymer dots for pattern encoding and superresolution imaging.

Two photoswitchable semiconducting polymers were synthesized by covalently incorporating photochromic dithienylethene (DTE) into the main chains. Small size polymer dots (Pdots) were prepared and showed dynamic photoswitching upon alternate light irradiation. By virtue of the tunable photoswitching properties, effective pattern encoding and superresolution imaging with a resolution of up to about 30 nm were achieved.

Intestinal microbiota-mediated dietary fiber bioavailability.

Dietary fiber is a kind of carbohydrate that cannot be digested and absorbed by the small intestine of humans but can be fermented in all or part of the large intestine and is significantly healthy for the human body. With the improvement in living standards, people pay more attention to their intestinal health, and the relationship between dietary fiber, intestinal microecological and body physiological balances, and their molecular connection mechanism has become a research hot spot. In this study, we reviewed its mediated bioavailability to provide a basis for the rational classification of dietary fiber and to guide the development of new healthy foods and the deep processing of food and its application.

Mechanistic insights into sulfate and phosphate-mediated hexavalent chromium removal by tea polyphenols wrapped nano-zero-valent iron.

Nano zero-valent iron via green synthesis (g-nZVI) has great potential in removing toxic hexavalent Cr(VI) from industrial wastewater. Sulfate and phosphate in wastewater can influence Cr(VI) removal by g-nZVI. In this study, the Cr(VI) removal kinetics by different g-nZVI materials were investigated with the existence of sulfate and/or phosphate, and the corresponding mechanisms were first revealed using multiple characterizations, including X-ray absorption near-edge spectra (XANES) and X-ray photoelectron spectroscopy (XPS). The results showed that Cr(OH)3 was the dominant species initially formed on the surface of g-nZVI particles before transforming to Cr2O3 during the reaction of g-nZVI with Cr(VI). Sulfate in wastewater can promote the reduction from Cr(VI) to Cr(OH)3 by g-nZVI, because sulfate triggers the release of Fe(II) and tea polyphenols (from tea extracts) from the g-nZVI surface due to the corrosion of Fe0 core, which is in line with an obvious increase in pseudo-second-order rate constant (k2) and subtle change in Cr(VI) removal capacity (qe). However, phosphate impedes the g-nZVI corrosion and inhibits qe because of the inner-sphere complexation of phosphate onto g-nZVI decreasing the released Fe(II) for Cr2O3 production. When sulfate and phosphate coexisted in contaminated water, the inhibition effect of phosphate in Cr(VI) removal by g-nZVI was stronger than the promotion of sulfate. Accordingly, qe value of g-nZVI declined from 93.4 mg g-1 to 77.5 mg g-1, while k2 remained constant as the molar ratio of phosphate/sulfate increased from 0.1 to 10 in water. This study provides new insights into applying g-nZVI in efficient Cr(VI) removal from contaminated water with enrichment of sulphates and phosphates.

The impact of laryngeal mask versus other airways on perioperative respiratory adverse events in children: A systematic review and meta-analysis of randomized controlled trials.

BACKGROUND: Increasing studies have shown that the use of laryngeal mask airways (LMAs) improved the perioperative respiratory adverse events (PRAEs) in children. However, the results of some of these studies still remained controversial as their sample sizes were small. A systematic review and meta-analysis was designed to evaluate the impact of LMAs in decreasing PRAEs in children. METHODS: We searched the Cochrane Library, PubMed, EMBASE and Web of Science up to May 29, 2018 to identify relevant randomized controlled trials (RCTs) which analyzed and evaluated the impact of LMAs in decreasing PRAEs in children. Participants were randomly assigned to receive LMAs (the intervention group) or other airways (the control group). We studied PRAEs which included breath apnea, laryngospasm, desaturation, cough, fever, pulmonary rales and pulmonary infection. Risk ratio (RR) with 95% confidence intervals (CIs) were estimated to compare the outcomes of the groups. We also performed subgroup analysis and sensitivity analysis to evaluate the impact of LMAs on further decreasing PRAEs. Two reviewers assessed the trial quality and extracted the data independently. All statistical analyses were performed using the standard statistical procedures provided in the Review Manager 5.2. RESULTS: Twelve RCTs (N = 1577 participants) were identified. Comparing with other airways, significant reduction were found in the overall PRAEs (RR 0.52, 95% CI 0.39-0.70; P < 0.0001), major PRAEs (RR 0.47, 95% CI 0.29-0.79; P = 0.004) as well as minor PRAEs (RR 0.57, 95% CI 0.45-0.74; P < 0.0001) in patients managed with LMAs. When compared with endotracheal tubes (ETTs), LMAs also significantly reduced PRAEs. Further analysis also found that LMAs reduced the incidences of postoperative cough (RR 0.44, 95% CI 0.31-0.63; P < 0.00001), pulmonary rales (RR 0.62, 95% CI 0.44-0.87; P = 0.006) and infections (RR 0.28, 95% CI 0.13-0.61; P = 0.001) in children. CONCLUSIONS: LMAs reduced the incidences of many PRAEs in children and should be used as one of anaesthesia methods for children.

Material Synthesis and Device Aspects of Monolayer Tungsten Diselenide.

In this paper, we investigate the synthesis of WSe2 by chemical vapor deposition and study the current transport and device scaling of monolayer WSe2. We found that the device characteristics of the back-gated WSe2 transistors with thick oxides are very sensitive to the applied drain bias, especially for transistors in the sub-micrometer regime. The threshold voltage, subthreshold swing, and extracted field-effect mobility vary with the applied drain bias. The output characteristics in the long-channel transistors show ohmic-like behavior, while that in the short-channel transistors show Schottky-like behavior. Our investigation reveals that these phenomena are caused by the drain-induced barrier lowering (short-channel effect). For back-gated WSe2 transistors with 280 nm oxide, the short-channel effect appears when the channel length is shorter than 0.4 µm. This extremely long electrostatic scaling length is due to the thick back-gate oxides. In addition, we also found that the hydrogen flow rate and the amount of WO3 precursor play an important role in the morphology of the WSe2. The hole mobility of the monolayer WSe2 is limited by Columbic scattering below 250 K, while it is limited by phonon scattering above 250 K. These findings are very important for the synthesis of WSe2 and accurate characterization of the electronic devices based on 2D materials.