Fast and Quantitative Electrical Detection of Iodine Based on a Polymer of Intrinsic Microporosity

Rapid, sensitive, and high-fidelity detection of toxic radioiodine species is of great importance for first responder activities in case of nuclear accidents. Robust active materials that enable concise device processing and direct online electrical detection of vaporous iodine under ambient conditions are promising and urgently required. Here, we explore the use of a polymer of intrinsic microporosity (PIM-1) as the sensing layer to directly detect the real-time iodine vapor using the electrochemical impedance spectroscopy (EIS) technique. Good solubility of PIM-1 makes it easy for thin film fabrication, while the intrinsic microporosity endows the sensor with strong signal amplification capability. The sensor exhibits marked electrical responses to iodine vapor, with high chemical selectivity (>105× over air, methanol, ethanol, and water), fast response (60 s at room temperature), as well as remarkable resistance change (107× at 30 °C for 5 min). The I2 adsorptive sensing is reversible by simple heating in the air enabling the sensor to be used for at least five cycles. In addition, the resistance change is linearly related to the iodine vapor concentration in the whole range tested, making it useful not only for the qualitative detection of iodine leakage but also for quantification. The report here demonstrates that merging EIS and PIMs can be a useful tool for the electrical sensing of gaseous toxins in the environment

A three-dimensional transient mixed hybrid finite element model for superabsorbent polymers with straindependent permeability

A hydrogel is a cross-linked polymer network with water as solvent. Industrially widely used superabsorbent polymers (SAP) are partially neutralized sodium polyacrylate hydrogel. The extremely large degree of swelling is one of the most distinctive characteristics of such hydrogels, as the volume increase can be about 30 times its original volume when exposed to the physiological solution. The large deformation resulting from the swelling demands a careful numerical treatment. In this work, we present a biphasic continuum-level swelling model using mixed hybrid finite element method (MHFEM) in three dimensions. The hydraulic permeability is highly dependent on swelling ratio, resulting in values that are orders of magnitude apart from each other. The property of local mass conservation of MHFEM contributes to a more accurate calculation of the deformation as the permeability across the swelling gel in a transient state is highly non-uniform. We show that the proposed model is able to simulate the free swelling of a random-shaped gel and squeezing of fluid out of a swollen gel. At last, we make use of the proposed numerical model to study the onset of surface instability in transient swelling

Comparing mixed hybrid finite element method with standard FEM in swelling simulations involving extremely large deformations

Swelling involving (extremely) large deformations simulations have wide range of applications in biomedicine, tissue engineering and hygienic product design. Typically, standard FEM is used in which deformations and chemical potential are chosen to be the prime variables. On the other hand, mixed hybrid finite element method (MHFEM) featuring an additional independent variable field flux possesses local mass conservation property. Such a property has shown its success in Darcy’s type equations with heterogeneous permeability. In this work, we perform a full-round comparison between MHFEM and FEM in solving swelling problems involving large deformations. Specifically, based on the permeability distributions, the problems fall into three categories: constant permeability, strain-dependent permeability and permeability with a discontinuous interface. For each category, we compare the two methods in aspects like solution convergence robustness, deformation, chemical potential and flux field accuracy and computational cost. We conclude that MHFEM outperforms standard FEM in terms of solution convergence robustness and the accuracy of all three fields when a swelling problem involves discontinuous interface in permeability

Graphdiyne-Supported NiFe Layered Double Hydroxide Nanosheets as Functional Electrocatalysts for Oxygen Evolution

Graphdiyne (GDY), a novel two-dimensional full-carbon material, has attracted lots of attention because of its high conjugated system comprising sp² and sp-hybridized carbons. The distinctive structure characteristics endow it unique electronic structure, uniform distributed pores and excellent chemical stability. A novel GDY-supported NiFe layered double hydroxide (LDH) composite was successfully prepared for the first time. By taking advantage of the increased surface active areas and improved conductivity, the designed hierarchical GDY@NiFe composite exhibits outstanding catalytic activity that only required a small overpotential about 260 mV to achieve the current density of 10 mA cm^–2. The nanocomposite shows excellent durability in alkaline medium implying a superior OER electrocatalytic activity. It is anticipated that the as-prepared GDY@NiFe composite electrocatalyst provide new insights in designing graphdiyne-supported electrocatalyst materials for oxygen evolution application

Real-Time Fluorometric Assay for Acetylcholinesterase Activity and Inhibitor Screening through the Pyrene Probe Monomer–Excimer Transition

A choline labeled pyrene probe (<b>Py-Ch</b>) was designed and synthesized. Poly(vinylsulfonate) (PVS) could induce <b>Py-Ch</b> aggregation. The aggregation and deaggregation process could be finely controlled by the acetylcholinesterase (AChE) enzymatic hydrolysis of <b>Py-Ch</b>. The resulting excimer–monomer transition provided a facile way for real-time AChE activity fluorometric assay and inhibitor screening

Nucleic Acid-Induced Tetraphenylethene Probe Noncovalent Self-Assembly and the Superquenching of Aggregation-Induced Emission

Superquenching of aggregation-induced emission (AIE) has been utilized in biosensing for the first time. A positively charged tetraphenylethene derivative (compound <b>1</b>) showed no emission in an aqueous buffer solution. A single-stranded DNA (a polyanion) induced aggregation of compound <b>1</b>, and strong compound <b>1</b> aggregate emission was observed. When the DNA was labeled with a quencher molecule, compound <b>1</b> aggregate emission was efficiently quenched. On the basis of this observation, a new, simple, sensitive and selective DNA methyltransferase (MTase) assay has been developed. A quencher-labeled double-stranded DNA could induce aggregation of compound <b>1</b>, and superquenching of compound <b>1</b> AIE was observed. In the presence of MTase and an endonuclease, the DNA could be specifically methylated and cleaved into single-stranded DNA fragments. The quencher molecule was released, and a turn-on emission signal was detected

In Situ Formation of Metal Coordination Polymer: A Strategy for Fluorescence Turn-On Assay of Acetylcholinesterase Activity and Inhibitor Screening

A novel method for the sensing of acetylcholinesterase (AChE) activity and inhibitor screening based on the formation of metal coordination polymer has been developed. Acetylthiocholine (ATCh) was selected as the substrate. In the presence of AChE, ATCh was hydrolyzed to thiocholine and acetate. Thiocholine interacted with Ag­(I) to form a metal coordination polymer. A positively charged perylene probe (probe 1) was employed. The fluorescence of probe 1 was very efficiently quenched by a polyanion [PVS, poly­(vinyl sulfonate)]. In the presence of acetylcholinesterase, the positively charged metal coordination polymer newly formed in situ would interact with PVS, probe 1 monomer molecules were released, and a turn on fluorescence signal was detected. The assay is highly sensitive, a limit of detection of 0.04 mU/mL AChE was obtained. The assay is also highly selective, a number of potential interference proteins (enzymes) were tested, and none of them show noticeable interference. Sensing of AChE inhibitor was also demonstrated. Our assay is fairly simple and inexpensive. We envision that it could be used for the sensitive detection of other hydrolytic enzyme activities with properly selected substrates and for the screening of potential inhibitor drugs

Image_1_Efficacy of high-flow nasal oxygenation compared with laryngeal mask airway in children undergoing ambulatory oral surgery under deep sedation: A randomized controlled non-inferiority trial.TIFF

BackgroundHigh-flow nasal oxygenation (HFNO) has been suggested as an alternative oxygenation method during procedural sedation. This randomized, non-inferiority trial evaluated the safety and efficacy of HFNO compared with laryngeal mask airway (LMA) in pediatric ambulatory oral surgery under deep sedation.MethodsIn total, 120 children aged 2–7 years (weight: 10–30 kg) were equally assigned into two groups, namely, HFNO with propofol total intravenous anesthesia infusion (HFNO-IV) or LMA with propofol total intravenous anesthesia infusion (LMA-IV). The primary objective was to monitor carbon dioxide (CO2) accumulation during perioperative surgery. Secondary objectives included monitoring transcutaneous oxygen saturation, grade exposure to the surgical field, perioperative adverse events, or other events. The predefined non-inferiority margin was 7 mmHg. During the COVID-19 pandemic, a novel WeChat applet was implemented to gather follow-up data after discharge.ResultsNon-inferiority could be declared for HFNO relative to LMA (mean difference in transcutaneous CO2 (TcCO2) = −1.4 mmHg, 95% CI: −2.9, 0.1 mmHg; P > 0.05). The pre-surgical TcCO2 of the HFNO-IV group (45.4 ± 4.5 mmHg) was similar to that of the LMA-IV group (44.0 ± 3.5 mmHg), within the clinically acceptable normal range. All the children maintained SpO2 levels of >97%. The surgical field exposure score of the HFNO group was significantly better than that of the LMA group. There was no significant difference between the two groups regarding risk or adverse events.ConclusionHFNO was not inferior to LMA for maintaining oxygenation and ventilation in patients undergoing pediatric ambulatory oral surgery under deep sedation under strict isolation from the oral cavity to the upper airway.</p

MithraDetective: A System for Cherry-picked Trendlines Detection.

Given a data set, misleading conclusions can be drawn from it by cherry-picking selected samples. One important class of conclusions is a trend derived from a data set of values over time. Our goal is to evaluate whether the 'trends' described by the extracted samples are representative of the true situation represented in the data. We demonstrate MithraDetective, a system to compute a support score to indicate how cherry-picked a statement is; that is, whether the reported trend is well-supported by the data. The system can also be used to discover more supported alternatives. MithraDetective provides an interactive visual interface for both tasks

The Effects of Roving After Each Training Session on Perceptual Learning

<div><p>(A–D) Post- versus pre-training contrast thresholds in practice conditions in which each regular temporal-patterned training session was followed by roving interference after a delay of (A) 0 h (<i>F</i>_1,5 = 1.48, <i>p =</i> 0.278), (B) 4 h (<i>F</i>_1,5 = 10.6, <i>p =</i> 0.022), (C) 8 h (<i>F</i>_1,5 = 42.0, <i>p =</i> 0.001), and (D) 12 h <i>(F</i>_1,5 = 13.1, <i>p =</i> 0.015).</p> <p>(E) PPR as a function of the delay of roving interference. The horizontal line indicates the PPR in regular temporal-patterned training without followed roving interference (<a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.0060197#pbio-0060197-g001" target="_blank">Figure 1</a>B).</p></div