Sonoelectrochemical exfoliation of defective black phosphorus nanosheet with black phosphorus quantum dots as a uric acid sensor.

To maintain human health, the development of rapid uric acid (UA) sensing is crucial. In this study, defective black phosphorus nanosheets with black phosphorus quantum dots (dBPN/BPQDs) were successfully and rapidly prepared by sonoelectrochemical exfoliation. In this process, the intercalation of phosphate ions into the black phosphorus working electrode was improved by coupling ultrasonic radiation with a high intercalating potential (8 V vs. Ag/AgCl/3M). The dBPN/BPQDs with various vacancies (5-9 defects, 5-7-7-5 defects, and 5-8-5 defect vacancies) exhibited a remarkable mass activity (jm, 1.22 × 10-3 mA µg-1) for uric acid oxidation, which was 5.92 times greater than that of reduced graphene oxide (rGO) (2.06 × 10-4 mA µg-1). In addition, the sensitivity of the dBPN/BPQD UA sensor was 474.2 µA mM-1 cm-2 in the linear analysis range of 0.1-1.3 mM. The sensitivity of the sensor was apparently higher than 67.7 µA mM-1cm-2 for rGO. The data from real sample experiments using serum showed that the dBPN/BPQD catalyst had high recoveries (97.3 %-100.2 %) and low related standard deviation (0.44 %-1.52 %). The dBPN/BPQDs exhibited the potential as an amperometric sensor to detect UA without needing enzymes.

Positive Airway Pressure at Extubation Minimizes Subglottic Secretion Leak In Vitro.

Accumulated secretion above the endotracheal tube cuff can be aspirated during extubation after deflation. The possible techniques for minimizing pulmonary aspiration from subglottic secretion during extubation have not been well explored. This study aimed to determine the effect of different extubation techniques on secretion leakage. An endotracheal tube was placed in a tube mimicking an airway. We measured the leak volume of water or artificial sputum of different viscosities with three extubation techniques-negative pressure with suctioning; positive pressure with a resuscitator; and continuous positive airway pressure set at 5, 10, and 20 cm H2O. Extubation with continuous positive airway pressure resulted in lower secretion leakage than that with negative pressure with suctioning and positive pressure with a resuscitator. Increasing the continuous positive airway pressure level decreased secretion leakage volume during extubation. We further determined a correlation of leak volume with sputum viscosity. Continuous positive airway pressure at 5 cm H2O produced lower volume secretion leakage than the other two techniques, even with higher secretion viscosity. Based on these results, using continuous positive airway pressure with a previous ventilator continuous positive airway pressure/positive end-expiratory pressure setting for extubation is recommended.

Potential-induced sonoelectrochemical graphene nanosheets with vacancies as hydrogen peroxide reduction catalysts and sensors.

Defective graphene nanosheets (dGN4V) with 5-9, 5-8-5, and point defects were synthesised by a sonoelectrochemical method, where a potential of 4 V (vs. Ag/AgCl) was applied to drive the rapid intercalation of phosphate ions between the layers of the graphite foil as a working electrode. In addition to these vacancies, double vacancy defects were also created when the applied potential was increased to 8 V (dGN8V). The defect density of dGN8V (2406 µm-2) was higher than that of dGN4V (1786 µm-2). Additionally, dGN8V and dGN4V were applied as catalysts for the hydrogen peroxide reduction reaction (HPRR). The mass activity of dGN8V (1.31 × 10-2 mA·µg-1) was greater than that of dGN4V (1.17 × 10-2 mA·µg-1) because of its high electrochemical surface area (ECSA, 1250.89 m2·g-1) and defect density (ND, 2406 µm-2), leading to low charge transfer resistance on the electrocatalytic interface. The ECSA and ND of dGN4V were 502.7 m2·g-1 and 1786 µm-2, respectively. Apart from its remarkable HPRR activity, the cost-effective dGN8V catalyst also showed potential as an amperometric sensor for the determination of H2O2.

Copper-induced synthesis of palladium/copper popcorn nanoparticles as sensors for differential pulse voltammetric determination of dopamine.

Popcorn nanoparticles (pop-NPs) consisting of a Pd/Cu alloy were synthesized using a seed-mediated growth method. The Cu and Pd atoms were co-deposited on a cubic Pd seed to reduce the energy of fault stacking. The same synthesis method with a reduced volume of the Cu(II) salt leads to Pd/Cu alloy nanoparticles with branches (br-NPs). Large Pd nanocubes (Pd NCs) were prepared via epitaxial deposition and using tetrachloropalladate (PdCl42-) only. The high-resolution TEM analysis results show the pop-NPs and br-NPs to be single crystals with [Formula: see text] and [Formula: see text] planes, respectively. The results of X-ray photoelectron spectroscopy and cyclic voltammetry measurements corroborated that Pd is enriched on both surfaces. The materials were placed on a glassy carbon electrode to obtain a differential pulse voltammetric sensor for dopamine (DA). The electrochemical sensitivities are (a) 1.55 µA µM-1 cm-2 for the Pd/Cu pop-NP sensor in its linear range (15-300 µM), (b) 1.17 µA µM-1 cm-2 for the br-NP sensor in the linear range (15-200 µM), and (c) 0.97 µA µM-1 cm-2 for the Pd NC sensor in its linear range (15-100 µM). The best working potentials are near 0.10 V (vs. SCE) for all three sensors. The pop-NP-based sensor performs particularly well due to it selectivity over ascorbic and uric acid. Graphical abstract Pd/Cu popcorn nanoparticles (pop-NPs), nanoparticles with branches (br-NPs), and Pd nanocubes (NCs) were synthesized using seed-mediated growth methods and directly used on glassy carbon electrodes for non-enzymatic sensing of dopamine.

Hydrothermal and plasma nitrided electrospun carbon nanofibers for amperometric sensing of hydrogen peroxide.

Nitrogen-doped carbon nanofibers (CNFs) were prepared by an electrospinning method, this followed by a hydrothermal reaction or nitrogen plasma treatment to obtain electrode for non-enzymatic amperometric sensing of H2O2. The hydrothermally treated electrode performs better. Its electrochemical surface is 3.7 × 10-3 mA cm-2, which is larger than that of a nitrogen plasma treated electrode (8.9 × 10-4) or a non-doped CNF (2.45 × 10-4 mA cm-2). The hydrothermally treated CNF with rough surface and a complex profile with doped N has a higher sensitivity (357 µA∙mM-1∙cm-2), a lower detection limit (0.62 µM), and a wider linear range (0.01-0.71 mM) than N-CNFP at a working potential of -0.4 V (vs. Ag/AgCl). The electrode gave high recoveries when applied to the analysis of milk samples spiked with H2O2. Graphical abstract Nitrogen-doped carbon nanofibers prepared by an electrospinning method followed by a hydrothermal reaction (N-CNFht) or nitrogen plasma treatment (N-CNFP) are directly used as non-enzymatic amperometric H2O2 sensors.

A comparison of nitrogen-doped sonoelectrochemical and chemical graphene nanosheets as hydrogen peroxide sensors.

Nitrogen-doped graphene nanosheet (N-SEGN) with pyrrolic nitrogen and 5-9 vacancy defects has been successfully prepared from a hydrothermal reaction of tetra-2-pyridinylpyrazine and sonoelectrochemistry-exfoliated graphene nanosheet, with point defects. Additionally, based on the same reaction using chemically reduced graphene oxide, nitrogen-doped chemically reduced graphene oxide (N-rGO) with graphitic nitrogen was prepared. The N-SEGN and N-rGO were used as a non-enzymatic H2O2 sensors. The sensitivity of the N-SEGN was 231.3 µA·mM-1·cm-2, much greater than 57.3 µA·mM-1·cm-2 of N-rGO. The N-SEGN showed their potential for being a H2O2 sensor.