A novel spectrophotometric method for the determination of aminophylline in pharmaceutical samples in the presence of methanol

A rapid, simple and sensitive method for the determination of aminophylline (Ami) using sodium 1, 2-naphthoquine-4-sulfonate (NQS) and methanol is established in this paper. It is based on the fact that a russety product can be formed by the reaction between aminophylline (Ami) and sodium 1, 2-naphthoquine-4-sulfonate (NQS) in pH 13.00 buffer solution. When methanol is added to the solution, the sensitivity of the color development reaction between Ami and NQS is improved, and the color of the system of NQS-Ami becomes a salmon pink. Beer's law is obeyed in a range of 4.97-69.5 microg ml(-1) of Ami at the maximum absorption of 453 nm (epsilon=4.87 x 10(3) l mol(-1) cm(-1)). The linear regression equation of the calibration curve is A=0.14458+0.00832C (microg ml(-1)), with a linear regression correlation coefficient of 0.9944. The detection limit is 0.7 microg ml(-1) (3sigma/k), R.S.D. is 1.1% and the recovery rate is in range of 92.5-105%. Furthermore, this method has been successfully applied to the determination of Ami in pharmaceutical samples.     

Qualitative and quantitative analyses of three bioactive compounds in different parts of Forsythia suspensa by high-performance liquid chromatography-electrospray ionization-mass spectrometry

A high-performance liquid chromatography-electrospray ionization-mass spectrometry (HPLC-ESI-MS) analytical method was developed to simultaneously detect and quantify three main distinctive compounds (forsythiaside, rutin and forsythin) in different parts of Forsythia suspensa (F. suspensa), an herbal medicine. This was the first report on the quantification of bioactive constituents in different parts of F. suspensa by HPLC-ESI-MS analytical method. The calibration curves of the three compounds showed good linearity (R² > 0.9994). The method was reproducible with intra- and inter-day variation less than 1.35% and 2.00%, respectively. The recovery of the assay was in the range of 98.27–101.07%. The results indicated that the developed assay could be considered as a suitable quality control method for this commonly used herbal medicine.     

High-throughput Synthesis of Solution-Processable van der Waals Heterostructures through Electrochemistry

Two-dimensional van der Waals heterostructures (2D vdWHs) have recently gained widespread attention because of their abundant and exotic properties, which open up many new possibilities for next-generation nanoelectronics. However, practical applications remain challenging due to the lack of high-throughput techniques for fabricating high-quality vdWHs. Here, we demonstrate a general electrochemical strategy to prepare solution-processable high-quality vdWHs, in which electrostatic forces drive the stacking of electrochemically exfoliated individual assemblies with intact structures and clean interfaces into vdWHs with strong interlayer interactions. Thanks to the excellent combination of strong light absorption, interfacial charge transfer, and decent charge transport properties in individual layers, thin-film photodetectors based on graphene/In₂Se₃ vdWHs exhibit great promise for near-infrared (NIR) photodetection, owing to a high responsivity (267 mA W⁻¹), fast rise (72 ms) and decay (426 ms) times under NIR illumination. This approach enables various hybrid systems, including graphene/In₂Se₃, graphene/MoS₂ and graphene/MoSe₂ vdWHs, providing a broad avenue for exploring emerging electronic, photonic, and exotic quantum phenomena.     

LiF and LiNO3 as synergistic additives for PEO-PVDF/LLZTO-based composite electrolyte towards high-voltage lithium batteries with dual-interfaces stability

Solid electrolytes with desirable properties such as high ionic conductivity,wide electrochemical stable window,and suitable mechanical strength,and stable electrode-electrolyte interfaces on both cathode and anode side are essential for high-voltage all-solid-state lithium batteries(ASSLBs)to achieve excellent cycle stability.In this work,a novel strategy of using LiF and LiNO₃ as synergistic additives to boost the performance of PEO-PVDF/LLZTO-based composite solid electrolytes(CSEs)is developed,which also promotes the assembled high-voltage ASSLBs with dual-interfaces stability characteristic.Specifically,LiF as an inactive additive can increase the electrochemical stability of the CSE under high cut-off voltage,and improve the high-voltage compatibility between cathode and CSE,thus leading to a stable cathode/CSE interface.LiNO₃ as an active additive can lead to an enhanced ionic conductivity of CSE due to the increased free-mobile Li+and ensure a stable CSE/Li interface by forming stable solid electrolyte interphase(SEI)on Li anode surface.Benefiting from the improved performance of CSE and stable dualinterfaces,the assembled NCM622/9[PEO₁₅-LiTFSI]-PVDF-15 LLZTO-2 LiF-3 LiNO₃/Li cell delivers a high rate capacity of 102.1 mAh g^-1 at 1.0 C and a high capacity retention of 77.4%after 200 cycles at 0.5 C,which are much higher than those of the ASSLB assembled with additive-free CSE,with only 60.0 mAh g^-1 and 52.0%,respectively.Furthermore,novel cycle test modes of resting for 5 h at different charge states after every 5 cycles are designed to investigate the high-voltage compatibility between cathode and CSE,and the results suggest that LiF additive can actually improve the high-voltage compatibility of cathode and CSE.All the obtained results confirm that the strategy of using synergistic additives in CSE is an effective way to achieve high-voltage ASSLBs with dual-interfaces stability.     

Adsorption Activity and Molecular Dynamics Study on Anti-corrosion Mechanism of Q235 Steel

The correlation between inhibition efficiency and molecular structures of the inhibitor during hydrochloric acid corrosion of Q235 steel was studied by quantum chemical calculations and molecular dynamics(MD) simulation. The proton affinity(PA) calculations demonstrated that 2-(quinolin-2-yl)quinazolin-4(3H)-one inhibitor has the tendency to be protonated in hydrochloric acid, which was in good agreement with experimental observations. Besides, quantum chemical parameters revealed that the protonated corrosion inhibitor molecules were more easily adsorbed on Q235 steel surface and improved the corrosion resistance of steel. MD simulations were implemented to search for the adsorption behavior of this molecule on Fe (110) surface, which might be used as a convenient tool for estimating the interaction mechanism between inhibitor and iron surface.     

光致清洁电极可见光在线更新与细胞实时监测

电化学传感器在用于细胞实时监测过程中,电极界面污染严重影响其检测性能.通过将纳米光催化剂与电化学传感材料复合,构建光致清洁电化学传感器,为电极界面的高效及无损更新提供了新思路.然而光催化产生的活性氧自由基导致细胞损伤,限制了细胞培养及检测过程中电极界面的实时更新.为此,我们在PEDOT@CdS/TiO₂/ITO可见光致更新电极表面旋涂明胶薄层,在保持电极良好的光致清洁和电化学传感性能同时,利用明胶薄层阻碍光催化产生的活性氧自由基扩散至细胞表面,显著降低了细胞损伤.此外,明胶优良的生物相容性有利于细胞的黏附及增殖.利用该电极,我们实现了人脐静脉内皮细胞（HUVECs）培养过程中,电极的在线更新以及细胞释放一氧化氮的实时监测.     

双硫腙改性的聚(二甲基丙烯酸乙二醇酯-甲基丙烯酸羟乙酯)微球的制备及其对铜离子的吸附研究

用悬浮聚合法由二甲基丙烯酸乙二醇酯(EGDMA)和甲基丙烯酸羟乙酯(HEMA)共聚制备得到聚(二甲基丙烯酸乙二醇酯-甲基丙烯酸羟乙酯)(PHEMA)微球,考察了NaOH浓度、反应时间等对用双硫腙进行PHEMA改性反应的影响以及铜离子水溶液浓度(5～500mg/L)、pH(2.0～6.5)、吸附时间等对改性后的微球对铜离子吸附性能影响的因素.改性的PHEMA微球对铜离子的最大吸附量为65.6mg铜离子/g双硫腙;而且,吸附有铜离子的改性PHEMA微球用0.1mol/L的硝酸的解吸率可达到90%以上,经过3次吸附-解吸循环后,解吸率仍基本不变,这表明双硫腙改性的PHEMA微球可以多次反复使用,具有良好的应用前景.     

一种铁基超导带材交流损耗的测量

近年来铁基超导材料的发现掀起了又一轮新型超导材料研究的热潮,各种配方的铁基超导材料不断被制备出来,转变温度也不断提高,中国科学家在该领域取得了十分突出的成果,制备出了多种铁基超导材料,但对其交流损耗特性研究鲜有报道,而实际应用中交流损耗的特性又十分重要,因此搭建了一套采用探测线圈法的交流损耗测量平台,测试了一种中国科学院电工研究所采用PIT工艺制作的单芯铁基超导带材的交流损耗。该文介绍了采用探测线圈法测量超导材料交流损耗的一种测量平台的搭建与标定,以及采用标定过的测量平台在液氦温度下测量的一种采用PIT工艺制作的单芯铁基超导带材的交流损耗;并与计算得到的铁基带材超导芯的磁滞损耗和包套的涡流损耗进行了比较分析,得出了其交流损耗与背景磁场频率成正比,其涡流损耗可以忽略的结论。     

New protocol for synthesis of new nanomaterials with continuous 3D networks

Nanostructured materials are attractive to researchers because of their unique optical, magnetic, thermodynamic, electrical, mechanical, and chemical properties. Controlling the morphology of nanomaterials could provide structural systems for a wide range of technologies. As a result, the development of nanofabrication techniques that are convenient and offer design flexibility is the subject of many studies. In order to progress beyond the conventional morphologies, we have turned to hydrogels, which can serve as organic templates for nanoscale objects with continuous microstructures. Transmission electron microscopy showed that the obtained nanonetwork had a continuous microstructure, which was several microns in length and width, with a cross-sectional diameter of 5–10 nm synthesized from a 35-g hexamethylenetetramine solution and a 1.5 g Zn(NO₃)₂ solution, and the cross-sectional diameter can be adjusted from 5 to 200 nm by controlling the concentration of the Zn(NO₃)₂ solution. Our results also showed that the nanostructures based on a superabsorbent polymer template could be controlled easily in terms of size and morphology by changing the concentration of the reaction solution. This protocol could be easily extended to synthesize a variety of nanostructured materials with novel morphologies.     

Narrowband optical parametric amplifier for efficient conversion of high-energy pulse with high beam quality

In a two-stage optical parametric amplifier based on KTiOAO4 crystals, we apply beam-overlapping technique to nanosecond signal pulse amplification, which results in high conversion efficiency and good beam quality. A signal pulse energy of 66 mJ at 1.572 μm wavelength is generated with 220 mJ of pump pulse input. A maximum gain of 66 and a maximum pump depletion of as high as 44% are determined. The spectral linewidth of the amplified signal pulse is around 50 MHz, and the beam quality factor of M 2 is less than 2.3.