A Tetrahedral Bisacridine Donor Enables Fast Radiative Decay in Thermally Activated Delayed Fluorescence Emitter

Achieving high efficiency and low efficiency roll-off simultaneously is of great significance for further application of thermally activated delayed fluorescent (TADF) emitters. A balance between radiative decay and reversed intersystem crossing must be carefully established. Herein, we propose a qunolino-acridine (QAc) donor composing two acridine with both planar (pAc) and bended (bAc) geometries. Combining with triazine, a TADF emitter QAc-TRZ is assembled. The pAc provides a well interaction with triazine which ensures a decent TADF behavior, while the bAc offers a delocalization of highest occupied molecular orbital (HOMO) which guarantees an enhancement of radiative decay. Remarkably, QAc-TRZ enables a highly efficient organic light emitting diode (OLED) with maximum external quantum efficiency (EQE) of 37.3 %. More importantly, the efficiencies under 100/1000 cd m⁻² stay 36.3 % and 31.7 %, respectively, and remain 21.5 % even under 10 000 cd m⁻².     

Sulfur Poisoning and Self-Recovery of Single-Site Rh1/Porous Organic Polymer Catalysts for Olefin Hydroformylation

Sulfur poisoning and regeneration are global challenges for metal catalysts even at the ppm level. The sulfur poisoning of single-metal-site catalysts and their regeneration is worthy of further study. Herein, sulfur poisoning and self-recovery are first presented on an industrialized single-Rh-site catalyst (Rh₁/POPs). A decreased turnover frequency of Rh₁/POPs from 4317 h⁻¹ to 318 h⁻¹ was observed in a 1000 ppm H₂S co-feed for ethylene hydroformylation, but it self-recovered to 4527 h⁻¹ after withdrawal of H₂S, whereas the rhodium nanoparticles demonstrated poor activity and self-recovery ability. H₂S reduced the charge density of the single Rh atom and lowered its Gibbs free energy with the formation of inactive (SH)Rh(CO)(PPh₃-frame)₂, which could be regenerated to active HRh(CO)(PPh₃-frame)₂ after withdrawing H₂S. The mechanism and the sulfur-related structure–activity relationship were highlighted. This work provides an understanding of heterogeneous ethylene hydroformylation and sulfur-poisoned regeneration in the science of single-atom catalysts.     

The Role of Sulfur in the S-PtRe/Al2O3 Catalysts: The Endogenous Deposition Effect on the Metal/acid Micro-environment

Alumina is widely used as support in the industrial catalytic process. As a common impurity, the sulfur species, which are often considered a harmful component, play a positive role in some petrochemical reactions. Herein, the S-modified catalysts were fabricated using the exogenous/endogenous deposition method to study the effect of the sulfur induced by introduction approaches. Series characterizations reveal that the exogenous sulfur from the sulfidation treatment affects the active metals by poisoning the low-coordinated sites, leading to the active metal sites decrease. As for the endogenous deposition method, besides the poison effect, the removal of the endogenous sulfur from the S-contain alumina support can produce oxygen vacancies, which can not only act as acid sites but work as an electron acceptor that optimizes the catalyst electronic structure. Benefits from the effect of endogenous sulfur, the catalyst with a suitable catalytic metal/acid micro-environment exhibit the best dehydrocyclization performance.     

Danggui Buxue Decoction: Comparative pharmacokinetic research on six bio-active components in different states by ultra-performance liquid chromatography-tandem mass spectrometry after oral administration

Danggui Buxue Decoction is a classic formula containing Astragali Radix and Angelicae Sinensis Radix in a 5:1 ratio and has been extensively used to treat blood deficiency for thousands of years. The aim of the study was to investigate the differences in plasma protein binding, pharmacokinetics, and tissue distribution of Danggui Buxue Decoction in normal and blood-deficient rats by ultra-performance liquid chromatography-tandem mass spectrometry. The effects on peripheral blood routine were verified. The compounds exhibited higher plasma protein binding and absorption in the model group compared to the control group, except formononetin. The six ingredients were distributed widely, and the highest concentrations were detected in the heart and uterus. As has been demonstrated in the previous study of the effect of Danggui Buxue Decoction, its potential is to serve as an effective traditional Chinese medicine formula for treating cardiovascular diseases and impacting estrogenic properties, which reveals the potential target organs of Danggui Buxue Decoction the heart and uterus. Our findings suggested that the absorption and distribution of different components in Danggui Buxue Decoction varies depending on the pathological state, molecular weight, lipid solubility, transporter-mediated efflux, and other factors.     

Preparation and application of surface enhanced Raman scattering substrate synthesized from single walled carbon nanotubes and silver nanoparticlesEI北大核心CSCD

By hydrothermal synthesis, silver nanoparticles (AgNPs) arranged on single-walled carbon nanotubes (SWCNTs) uniformly, and a SiO2/CNTs/AgNPs surface enhanced Raman scattering (SERS) substrate with composite open structure was prepared. The synthesized SiO2/CNTs/AgNPs were characterized by transmission electron microscopy (TEM. Using rhodamine 6G(R6G) as the probe molecule, the enhancement factor (EF) was 1.23×108, and the standard deviation was 2.31. Taking the phenol red, a common water pollutant, as the practical sample, the concentration of phenol red in the range of 1×10-4 -1×10-10 mol/L had a great exponential fitting relationship with its Raman signal intensity at 1153 cm-1 and 1441 cm-1, and the correlation coefficient (R2) was 0.99991. The substrate can realize the qualitative and quantitative detection of practical samples. © 2023, Youke Publishing Co.,Ltd. All rights reserved.     

Structural Evolution of PGA Nascent Fiber during Single Low-Temperature and Segmented High-Temperature Hot Stretching

Polyglycolide(PGA) fibers applied as surgical sutures strongly depend on their microstructure. The structural evolution of PGA nascent fibers during single low-temperature stretching and segmented high-temperature stretching was analyzed based on a combination of in situ WAXD/SAXS and DSC measurements. The results indicated that the hot stretching was conducive to the crystal perfection and the local fragmentation and recrystallization of the lamellar crystals may occur under stress induction. T...     

A modified QuEChERS-gas chromatography-mass spectrometry method for the determination of pesticide residues in Lonicera japonicae FlosEI北大核心CSCD

A modified QuEChERS-gas chromatography-mass spectrometry method using multi-walled carbon nanotubes （MWCNTs）as adsorbent was established for the determination of 72 pesticide residues in Lonicera japonicae Flos. The sample was extracted with Association of Official Agricultural Chemists （AOAC）extracting package,purified with MWCNTs-modified purification tube,analyzed with dynamic multiple reaction monitoring mode,and quantified with external standard method of matrix-matched standard curve. The 72 pesticides showed good linearities in the corresponding concentration ranges with correlation coefficients greater than 0.9936. The limits of detection were 0.001-0.178 μµg/kg,and the limits of quantitation were 0.002-0.593 μµg/kg. The average recoveries for four spiked levels ranged from 60.1% to 118.0%,with the relative standard deviations of 2.2%-17%. © 2023, Youke Publishing Co.,Ltd. All rights reserved.     

脱氢枞酸酯键合硅胶色谱固定相的制备及应用

A dehydroabietic acid glycidyl methacrylate ester (DAGME)-bonded silica stationary phase (Sil-DAGME) was fabricated in this paper. The DAGME was firstly prepared using dehydroabietic acid and glycidyl methacrylate via a ring-opening addition reaction, and then grafted onto the surface of a thiol-functionalized spherical silica by click reaction to obtain the Sil-DAGME. The successful immobilization of DAGME on the silica was confirmed through series of characterizations including Fourier-transform infrared spectroscopy (FT-IR), thermal gravimetric analysis (TGA)and elemental analysis (EA). The chromatographic performance and retention mechanisms of Sil-DAGME were validated using a variety of compounds including alkylbenzenes, Tanaka standard test mixtures, polycyclic aromatic hydrocarbons, phenols and flavonoids. Meanwhile, the Sil-DAG⁃ME exhibits multiple interactions, including hydrophobic, π-π and hydrogen bonding interaction between the stationary phase and the analytes during the separation process due to the co-existing of benzene ring, carbonyl group, hydroxyl group and hydrophobic rigid tricyclic hydrophenanthrene skeleton in the DAGME on the silica surface. Based on synergistic action of multiple retention mechanisms, the probe molecules metioned above achieved ideal resolution and flexible selectivity in separation. In addition, the Sil-DAGME not only exhibited good stability, repeatability and reproducibility with the run-to-run relative standard deviations (RSDs) of 0. 050%-0. 19% (n = 10), the daytoday RSDs of 0. 25%-1. 0% (n = 7), and the column-to-column RSDs of 0. 78%-2. 1% (n = 3) for the retention time, but also showed an excellent separation ability for Yew tree bark extract. In short, the application of dehydroabietic acid in chromatographic separation materials not only provided a new approach for the separation and detection of paclitaxel, but also presented a reference for the design stationary phase using natural product rosin as functional ligand. © 2023, China Association for Instrumental Analysis. All rights reserved.     

多单体接枝聚丙烯对PBT/PP共混体系的形态结构及力学性能影响研究

研究了甲基丙烯酸缩水甘油酯 (GMA)和苯乙烯 (St)多单体熔融接枝聚丙烯 (PP g (GMA co St) )对聚对苯二甲酸丁二酯 (PBT) 聚丙烯 (PP)共混物的形态结构和力学性能的影响 .利用双螺杆挤出机对PBT PP合金进行共混挤出 ,使用DSC、FT IR和SEM、TEM等手段对共混物进行了分析和相形态观察 ,并测试了力学性能 .实验证明 ,熔融共混过程中PP g (GMA co St)的环氧基团可以与PBT的端羧基发生化学反应 ,就地生成了PBT g PP共聚物 ,该共聚物可对PBT PP合金起到良好的增容剂作用 ,使共混物的相区尺寸显著减小 ,共混物的拉伸强度和冲击强度等力学性能同时得到明显改善 ,达到了弹性体系或小分子增容所难以达到的力学性能平衡的效果 .此外 ,TEM的研究还在PBT PP g (GMA co St)共混物中发现了特殊的微相分离结构     

基于LIBS技术的水泥粉末在线成分分析

在工业现场生产水泥的过程中，各种成分的含量直接影响着水泥的质量，因此如何快速准确地监测水泥中各个成分的含量意义重大。采用的实验方式为，将不经过任何预处理的水泥粉末直接放入位于二维移动平台上的物料盒中，通过激光诱导击穿光谱(LIBS)直接对水泥粉末表面的不同位置进行激发检测，对得到的光谱数据首先进行归一化和主成分分析等预处理操作，然后针对水泥中Ca, Si, Al, Fe, Mg五种元素，分别建立偏最小二乘(PLS)和支持向量回归(SVR)两种定量分析模型进行方法比较。此外，对比了粉末状水泥与压片式水泥两种测量方式的结果。实验结果表明，采用粉末状水泥直接测量的方式下，针对水泥样品元素浓度与所得到的光谱中特征线强度的关系，SVR方法比PLS方法更具优势，粉末状水泥直接测量的精度接近压片式测量的精度，说明LIBS技术对水泥粉末状样品直接在线测量具有可行性。