Quantum-Sized SnO2 Nanoparticles with Upshifted Conduction Band: A Promising Electron Transportation Material for Quantum Dot Light-Emitting Diodes.

In previous reports of the literature, ZnO nanoparticles were unexceptionally used as the electron transportation material in highly efficient CdSe-based quantum dot light-emitting diodes (QD-LEDs). However, as an amphoteric oxide, ZnO nanoparticles are chemically unstable in air. Here, we utilize quantum-sized SnO2 nanoparticles as the electron transportation layer (ETL) of CdSe-based QD-LEDs. Decreasing the size of SnO2 nanoparticles will upshift the conduction band from -4.50 to -3.84 eV based on the quantum size effect, which is beneficial to facilitate electron injection into the QD emitting layer. Our investigations show that QD-LEDs based on quantum-sized SnO2 nanoparticles exhibit comparable electroluminescence properties and higher stability in contrast to ZnO nanoparticle-based QD-LEDs, demonstrating that small-sized SnO2 nanoparticles have a bright prospect due to the ETL in QD-LEDs.

A vital sign signal noise suppression method for wearable piezoelectric devices.

This paper tackles the problem of noise suppression during vital sign signal monitoring. Physiological signal monitoring is a significant and promising medical monitoring method, and wearable medical monitoring devices based on piezoelectric polymer sensors are a trending way for their advantages of being flexible in the shape, portable to use, and comfortable to wear. However, this raises the question that the measured signal contains much more noise components. To avoid the following shortcoming of low signal to noise ratio (SNR), a noise suppression method based on improved wavelet threshold and empirical mode decomposition combined with singular value decomposition (SVD) screening the intrinsic mode function (IMF) components is proposed. A wavelet transform is first used under the combination of hard and soft thresholds to focus the target range in the low-frequency region where the energy of the physiological signal is concentrated. Then, a complete ensemble empirical mode decomposition is used to decompose the signal effectively, which can resist the influence of random noises. Meanwhile, a SVD decomposition procedure was used to filter out the lower correlated IMF components to retain the validity of the original signal. We verified the effectiveness of the proposed method through simulated and measured experiments as well as the advantages and disadvantages of the algorithm compared with other physiological signal denoising algorithms through SNR filtering results, power spectrum distribution, and other perspectives. The results proved that the proposed method could effectively remove more detailed noise and improve the SNR of the signal efficiently, which is more conducive to the demand for auxiliary medical diagnosis in the future.

Recent advances in thermo-sensitive hydrogels for drug delivery.

Hydrogels are cross-linked hydrophilic macromolecules that contain a certain amount of water. Due to their biocompatible, highly tunable and hydrophilic nature, hydrogels have attracted much attention in the applications of chemical, biomedical and pharmaceutical fields over the past twenty years. In particular, thermo-sensitive hydrogels, which can undergo phase transition or swell/deswell as ambient temperature changes, endow the drug delivery system with enhanced local drug penetration, desirable spatial and temporal control, and improved drug bioavailability. These merits facilitate their extensive applications in drug delivery. In this review, we focus on advances in the development of different thermo-sensitive polymers as a scaffold for drug delivery, including poly(N-isopropylacrylamide) (pNIPAAM), poloxamer, polyethylene glycol/poly(lactic acid)co-(glycolic acid) (PEG/PLGA), and chitosan. The state-of-the-art thermo-sensitive hydrogels for various pharmaceutical applications, such as anti-tumor drug delivery, transdermal drug delivery, ocular drug delivery, nasal drug delivery, and buccal drug delivery, are elaborated. Finally, the future research perspectives and challenges are also discussed, which could facilitate the translation of thermo-sensitive hydrogels for drug delivery from bench to bedside.

Electrochemical performance of a new all solid-state ultra-low noise electrospray electrode as a marine electric field sensor.

A new type of Ag/AgCl electrode as a marine electric field sensor is prepared using electrospray. The surface of the electrode is porous, and the particle size of AgCl is small and uniform with an average particle size of 1.43 µm, which accelerated the speed of the oxidation-reduction reactions. Therefore, the electrode with large specific surface area has high stability and low noise. The impedance, sensitivity, self-noise, and stability of the electrode are measured to study the electrochemical performance of the electrode. The impedance of the electrode is 7.9 Ω, and the electrode shows resistance characteristics, meaning that the electrode can well receive the weak ocean electric field signals with low signal distortion. The sensitivity experiment result shows that the electrode can well restore the sinusoidal electric field signal of 1 Hz (10 mV). The voltage drift is less than 5 µV/100 h, the self-potential is between -51 and 56 µV, and the self-noise of the electrode is 2.48 nV @ 1 Hz. The AgCl layer on the surface of the electrode is porous and thick, and the particle size of AgCl is small and uniform. This makes the electrode have excellent electrochemical performance. All the experimental results show that the electrode has ultra-low noise and excellent response to low frequency weak electric field signals. The electrode is of great significance to the exploitation of marine resources as the marine electric field sensor.