Preparation of bamboo-derived magnetic biochar for solid-phase microextraction of fentanyls from urine

In this study, a biochar-based magnetic solid-phase microextraction method, coupled with liquid chromatography–mass spectrometry, was developed for analyzing fentanyl analogs from urine sample. Magnetic biochar was fabricated through a one-step pyrolysis carbonization and magnetization process, followed by an alkali treatment. In order to achieve desired extraction efficiency, feed stocks (wood and bamboo) and different pyrolysis temperatures (300–700°C) were optimized. The magnetic bamboo biochar pyrolyzed at 400°C was found to have the greatest potential for extraction of fentanyls, with enrichment factors ranging from 58.9 to 93.7, presumably due to H-bonding and π–π interactions between biochar and fentanyls. Various extraction parameters, such as type and volume of desorption solvent, pH, and extraction time, were optimized, respectively, to achieve the highest extraction efficiency for the target fentanyls. Under optimized conditions, the developed method was found to have detection limits of 3.0–9.4 ng/L, a linear range of 0.05–10 μg/L, good precisions (1.9–9.4% for intrabatch, 2.9–9.9% for interbatch), and satisfactory recoveries (82.0–111.3%). The developed method by using magnetic bamboo biochar as adsorbent exhibited to be an efficient and promising pretreatment procedure and could potentially be applied for drug analysis in biological samples.     

Suppression of charge imbalance via Li+-Mn4+ co-incorporated Sr2YSbO6 red phosphors for warm w-LEDs

Mn⁴⁺-activated double perovskite phosphors with composition diversity have presented excellent luminescent performances. However, the charge imbalance between Mn⁴⁺ and matrix cations would increase non-radiative recombination and reduce the structural stability. Here, novel high-efficiency stable Li⁺/Mn⁴⁺ co-incorporated Sr₂YSbO₆ red phosphors are successfully synthesized via a solid-state reaction method for warm w-LEDs, where the Li⁺ ions have the effect of charge balance for Sr₂YSbO₆:Mn⁴⁺ and reduce the non-radiative energy transfer among Mn⁴⁺ ions. It is demonstrated that the substitution of Li⁺–Mn⁴⁺ pairs for Sb⁵⁺ can enhance the bonding with low-shifted diffraction peaks and high emission intensity, and prolong the decay lifetime, compared with those of Mn⁴⁺ single-doped ones. Impressively, the thermal stability is enhanced to 89.72% from 84.61% at the original value of 303 K. Finally, a w-LED device based on the optimal phosphor Sr₂YSbO₆:0.01Mn⁴⁺/0.01Li⁺ red component exhibits a correlated color temperature of 4487 K and color rendering index of 80.2. Therefore, the incorporated Li⁺ ions serve as both charge compensator and co-activator in Mn⁴⁺-activated double perovskite phosphors with the aim of high luminescent performance and thermal stability.     

Ultrafast synthesis of near-infrared-emitting aqueous CdTe/CdS quantum dots with high fluorescence

The traditional aqueous route to synthesis CdTe/CdS Core/shell (c/s) quantum dots (QDs) via decomposition of Cd-thiol complexes is usually time consuming. Herein, an ultrafast and facile aqueous synthetic approach under atmospheric pressure for CdTe/CdS c/s QDs with emission from the green to the near-infrared window (535–820 nm) is reported. With purified CdTe core QDs diluted in solution of Cd-3-mercaptopropionic acid (MPA) complexes, CdTe/CdS c/s QDs with emission wavelengths at 700 and 800 nm can be obtained within 20- and 45-min refluxing under the optimized experimental conditions, respectively. This is the most rapid way to prepare CdTe/CdS c/s QDs in aqueous phase, and the obtained QDs were highly luminescent without postsynthesis treatment. The influences of various experimental factors, including Cd²⁺ concentration, MPA-to-Cd ratio, pH value, and dilution ratio on the growth rate and luminescent properties of the obtained CdTe/CdS c/s QDs, have been taken into consideration. The three processes “purification-dilution-addition” ensure the synthesis environment with high pH value and low core concentration and have a marked impact on the rapid synthesis rate and the resulting high fluorescence of CdTe/CdS c/s QDs.     

Sunflower-Like Nanostructure with Built-In Hotspots for Alpha-Fetoprotein Detection

In the present study, a sunflower-like nanostructure array composed of a series of synaptic nanoparticles and nanospheres was manufactured through an efficient and low-cost colloidal lithography technique. The primary electromagnetic field contribution generated by the synaptic nanoparticles of the surface array structures was also determined by a finite-difference time-domain software to simulate the hotspots. This structure exhibited high repeatability and excellent sensitivity; hence, it was used as a surface-enhanced Raman spectroscopy (SERS) active substrate to achieve a rapid detection of ultra-low concentrations of Alpha-fetoprotein (AFP). This study demonstrates the design of a plasmonic structure with strong electromagnetic coupling, which can be used for the rapid detection of AFP concentration in clinical medicine.     

Exponential stabilization of chaotic systems with delay by periodically intermittent control

This paper studies the exponential stabilization problem for a class of chaotic systems with delay by means of periodically intermittent control. A unified exponential stability criterion, together with its simplified versions, is established by using Lyapunov function and differential inequality techniques. A suboptimal intermittent controller is designed with respect to the general cost function under the assumption that the control period is fixed. Numerical simulations on two chaotic oscillators are presented to verify the theoretical results.     

基于大功率LED扩展光源的均匀光斑光辐射模拟器设计

基于边缘光线原理和光学扩展量守恒思想,结合复合抛物面聚光器和轴对称自由曲面透镜,设计并研制了大功率发光二极管扩展光源的反射/折射准直器.运用Tracepro软件对系统进行光束追迹模拟仿真和实验,研制出均匀光斑的光辐射模拟器.模拟器输出发散角为±12°光束,测量距离出射面50cm处光屏的光斑,在尺寸为14cm×14cm的光照范围内,测得光斑水平方向中心线上的光度均匀度优于4.1%,竖直方向中心线上的光度均匀度优于3.8%.     

Thin solid state reference electrodes for use in solid polymer electrolytes

This paper reports two low-profile (~ 10 μm thick) solid state reference electrodes for use in solid polymer electrolytes. The thin, open geometry of the electrodes enables close positioning between the working and counter electrodes. The first electrode uses the palladium hydride (Pd|PdH_x) couple (PHRE), and the second utilises the hydrous iridium oxide (IrO_x·yH₂O|IrO_a·bH₂O) couple (IORE). To our knowledge this is the first use of the latter as a reference electrode. The PHRE had a stable potential of + 70 mV vs RHE with a 4 mV h^− 1 drift and two hour lifetime, whilst the IORE gave a potential of + 847 mV vs RHE with a drift of 0.3 mV h^− 1 and no deterioration after 24 h of use. The use of these reference electrodes in a three-electrode solid state cell and a fuel cell is demonstrated.     

In silico analysis of proteins and microRNAs related to human African trypanosomiasis in tsetse fly

Human African trypanosomiasis (HAT), also known as sleeping sickness, causes millions of deaths worldwide. HAT is primarily transmitted by the vector tsetse fly (Glossina morsitans). Early diagnosis remains a key objective for treating this disease. MicroRNAs (miRNAs) are evolutionarily conserved small non-coding RNAs that play key roles in vector-borne diseases. To date, the roles of proteins and miRNAs in HAT disease have not been thoroughly elucidated. In this study, we have re-annotated the function of protein-coding genes and identified several miRNAs based on a series of bioinformatics tools. A batch of 81.1 % of tsetse fly proteins could be determined homology in mosquito genome, suggesting their probable similar mechanisms in vector-borne diseases. A set of 11 novel salivary proteins and 14 midgut proteins were observed in the tsetse fly, which could be applied to the development of vaccine candidates for the control of HAT disease. In addition, 35 novel miRNAs were identified, among which 10 miRNAs were found to be unique in tsetse fly. Pathway analysis of these 10 miRNAs indicated that targets of miR-15a-5p were significantly enriched in the HAT-related neurotrophin signaling pathway. Besides, topological analysis of the miRNA-gene network indicated that miR-619-5p and miR-2490-3p targeted several genes that respond to trypanosome infection, including thioester-containing protein Tep1 and heat shock protein Hsp60a. In conclusion, our work helps to elucidate the function of miRNAs in tsetse fly and establishes a foundation for further investigations into the molecular regulatory mechanisms of HAT disease.     

Infrared image enhancement through saliency feature analysis based on multi-scale decomposition

To improve contrast between dim target region and background in infrared (IR) long-range surveillance, this paper proposes a fast image enhancement approach using saliency feature extraction based on multi-scale decomposition. Firstly, a smooth based multi-scale decomposition is designed and applied to original infrared image, generating sub-images with various frequency components at different decomposition levels. The dim target regions of sub-images are extracted by a local frequency-tuned based saliency feature detection method, secondly. With saliency maps created by saliency extraction using multi-scale local windows with different sizes, the sub-images are enhanced at different decomposition scales. Finally, the enhanced result is reconstructed by synthesizing the all sub-images with adjustable synthetic weights. Since salient areas are analyzed based on fast multi-scale image decomposition, IR image can be s enhanced with good contrast successfully and rapidly. Compared with other algorithms, the experimental results prove that the proposed method is robust and efficient for IR image enhancement.