Novel superabsorbent polymer composites based on α-cellulose and modified zeolite: synthesis,characterization, water absorbency and water retention capacity

Cellulose - Most superabsorbent polymers (SAPs) are prepared based on synthetic polymers (from petroleum resources), making them costly, nondegradable, and not ecofriendly. To overcome these...     

Supercritical fluid chromatography tandem mass spectrometry employed with evaporation-free liquid–liquid extraction for the rapid analysis of cinnarizine in rat plasma

Cinnarizine is a weak base, which can produce supersaturation and precipitation during gastrointestinal transit, affecting its absorption in vivo. Therefore, it is necessary to investigate whether the oral bioavailability of cinnarizine can be improved after co-administration with precipitation inhibitors or not. In order to evaluate the pharmacokinetic behavior of cinnarizine in rats, a simple, rapid, sensitive, and environmentally friendly supercritical fluid chromatography-tandem mass spectrometric method was established and validated. In this method, flunarizine, a structural analogue of cinnarizine, was selected as the internal standard, and cinnarizine was extracted from rat plasma using evaporation-free liquid–liquid extraction method. The analytes were separated on a Torus 1-AA column (3.0 mm × 100 mm, 1.7 μm) within 2.0 min, using a gradient elution procedure. The transitions of cinnarizine and flunarizine were m/z 369.1 → 167.1 and m/z 405.1 → 203.1, respectively. Cinnarizine showed good linear correlation in the range of 1–500 ng/ml with a lower limit of quantification of 1 ng/ml. The intra- and interday precision and accuracy of all quality control samples were within ±15%. This high-throughput, accurate, sensitive, and reproducible method has been successfully applied to study the effects of the precipitation inhibitor cinnarizine on the pharmacokinetics in rats.     

A bio‐safe cyclophosphazene derivative flame retardant for polylactic acid composites: Flammability and cytotoxicity

An efficient bio‐safe cyclophosphazene flame retardant, 1,5,9,13,16,20‐Hexaoxa‐7,14,21‐triaza‐6λ⁴,8λ⁴,5λ⁴‐triphosphatrispiro[5.1.5.1.5.1]heneicosa‐6,8(14),15(21)‐triene (HCPO), was synthesized, and then was incorporated into polylactic acid (PLA) to improve the fire safety. The chemical structure of HCPO was confirmed by Fourier‐transformed infrared spectroscopy, mass spectrometry, and nuclear magnetic resonance spectroscopy. The thermal stability of the compound was characterized by thermogravimetric (TG) analyzer. The cytotoxic effects of HCPO to cells were evaluated. Fire behavior and thermal stability of PLA composites were investigated by vertical burning, limiting oxygen index (LOI), TG analysis, and cone calorimeter. The morphology of residual charring was observed by scanning electron microscope. The results showed HCPO was bio‐safe, and highly effective to enhance the flame retardancy of PLA composites. The LOI value was increased from 18.4 to 27.5 and UL‐94 grade achieved V‐0 for the PLA composite containing only 2% HCPO and 2% pentaerythrotol. It was demonstrated that intermolecular cross‐linking reaction between pentaerythrotol and HCPO in high temperature range could accelerate the formation of compact char layers.     

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.     

Preliminary investigation into feasibility of dissolved methane measurement using cavity ringdown spectroscopy technique

For the exploration of gas hydrate resources by measuring the dissolved methane concentration in seawater, a continuous-wave cavity ringdown spectroscopy (CW-CRDS) experimental setup was constructed for trace methane detection. A current-modulation method, rather than a cavity-modulation method using an optical switch and a piezoelectric transducer, was employed to realize the cavity excitation and shutoff. Such a current-modulation method enabled the improvement of the experimental setup construction and stability, and the system size and stability are critical for a sensor to be deployed underwater. Ringdown data acquisition and processing were performed, followed by an evaluation of the experimental setup stability and sensitivity. The obtained results demonstrate that great errors are introduced when a large fitting window is selected if the analog-to-digital converter has an insufficient resolution. The ringdown spectrum of methane corresponding to the 2v ₃ band R(4) branch was captured, and the methane concentration in lab air was determined to be 2.06 ppm. Further experiments for evaluating the quantitative ability of this CW-CRDS experimental setup are underway from which a high-sensitivity methane sensor that can be combined with a degassing system is expected.     

纳米二硫化钼的掺杂及催化电解水产氢的研究进展

电催化水分解制氢是可以形成闭环的生产过程, 起始原料与副产物均为水、 过程清洁无污染, 是极具希望的产氢策略. 目前制约其发展的瓶颈之一是价格昂贵的Pt基贵金属催化剂. 为推动电催化分解水制氢的普及, 亟待开发低成本非贵金属催化剂. 在众多备选非贵金属催化材料中, 纳米层状结构二硫化钼(MoS₂)因催化效果可期、 价格低而获得了广泛关注. 然而, 通常条件下易于获得的层状结构2H相MoS₂大面积的基面部分显示惰性, 仅在片层边缘处存在少量活性位点, 且导电性较差, 因而尚不能替代Pt基催化剂, 而如何增加其活性位点数量和提高其导电性成为亟待解决的问题; 另一方面, 1T相MoS₂虽然活性高、 导电性好, 但却存在制备困难及稳定性差的问题. 鉴于此, 研究者通过对纳米MoS₂进行掺杂改性实现了其活性与稳定性的有效提升. 本文对非贵金属纳米MoS₂催化剂掺杂改性的方法、 机理及其电催化水解制氢性能的相关研究进行了总结与讨论. 作为典型的非贵金属电解水析氢催化剂, MoS₂具有巨大发展潜力, 本文能够对相关非贵金属催化剂的研发提供有益的参考.     

低功率超声增强碘帕醇氯氧化的效果和路径

研究了低功率超声(US, <38 W)对NaClO氧化非离子型碘代X射线造影剂—碘帕醇(IPM)的增强作用及机理, 考察了NaClO添加浓度和超声功率的影响, 分析并计算了体系中的主要活性物种及其贡献. 采用高效液相色谱/串联质谱(HPLC/MS/MS)对降解产物进行分析, 推测IPM的降解路径. 结果表明, 低功率US显著增强了NaClO对IPM的氧化效果, 在25 ℃, pH=5.8, NaClO浓度为0.12 mmol/L条件下, 10 mg/L IPM在60 min的降解率达到85.8%. 其中NaClO氧化、 HO·和活性氯自由基(RCSs)是US/NaClO增强IPM降解的主要原因, 自由基分析计算它们的贡献率分别为15.82%, 4.65%和79.53%. NaClO浓度在0~0.24 mmol/L范围内, IPM的降解率随NaClO浓度升高而增加, 60 min后降解率由4.75%增加到91.12%; 超声功率为28.5 W, 降解率达到最高. 在 15~45 ℃温度范围内, IPM的降解过程符合表观一级反应动力学, 反应活化能(E_a)为59.03 kJ/mol. HPLC/MS/MS共检测出5种中间产物, 结合密度泛函理论(DFT)计算结果, 初步推测了IPM在US/NaClO体系中的降解途径和机理.     

Contradictory effect of gold nanoparticle-decorated molybdenum sulfide nanocomposites on amyloid-β-40 aggregation

The effect of gold nanoparticle-decorated molybdenum sulfide (AuNP-MoS₂) nanocomposites on amyloid-β-40 (Aβ₄₀) aggregation was investigated. The interesting discovery was that the effect of AuNP-MoS₂ nanocomposites on Aβ₄₀ aggregation was contradictory. Low concentration of AuNP-MoS₂ nanocomposites could enhance the nucleus formation of Aβ₄₀ peptides and accelerate Aβ₄₀ fibrils aggregation. However, although high concentration of AuNP-MoS₂ nanocomposites could enhance the nucleus formation of Aβ₄₀ peptides, it eventually inhibited Aβ₄₀ aggregation process. It might be attributed to the interaction between AuNP-MoS₂ nanocomposites and Aβ₄₀ peptides. For low concentration of AuNP-MoS₂ nanocomposites, it was acted as nuclei, resulting in the acceleration of the nucleation process. However, the structural flexibility of Aβ₄₀ peptides was limited as the concentration of AuNP-MoS₂ nanocomposites was increased, resulting in the inhibition of Aβ₄₀ aggregation. These findings suggested that AuNP-MoS₂ nanocomposites might have a great potential to design new multifunctional material for future treatment of amyloid-related diseases.