荷移反应分光光度法测定苯巴比妥钠

采用分光光度法研究了电子给体苯巴比妥钠与π电子受体茜素红的荷移反应,建立了荷移分光光度法测定苯巴比妥钠的方法。在水溶液中,苯巴比妥钠与茜素红荷移络合物的最大吸收波长为530 nm,该络合物的组成为1∶1,表观摩尔吸光系数ε为4.43×103L.mol-1.cm-1,稳定常数为2.30×105。药物质量浓度在5~40 mg/L范围内符合比尔定律,相关系数为0.9996。当苯巴比妥钠浓度为20 mg/L时,10次测定结果的相对标准偏差为1.3%。测定了针剂中的苯巴比妥钠,加标回收率在98.9%~105%之间。     

荷移光度法测定依诺沙星

依诺沙星与茜素红在水-乙醇介质中发生电荷转移反应,其中依诺沙星是电子给予体,茜素红是电子接受体,依据此荷移反应建立了一种快速测定依诺沙星的荷移分光光度法.荷移络合物在 546 nm 波长处有最大吸收,表观摩尔吸光率为 8.04×103L·mol-1·cm-1,相关系数为0.999 9.该络合物的组成为 1:1,表观稳定常数为 2.84×104.依诺沙星的质量浓度在 0～40 mg·L-1范围内服从比耳定律.当依诺沙星的质量浓度为 20 mg·L-1时,测定结果的相对标准偏差(n=6)为 1.2%,回收率在 99%以上.测定了依诺沙星制剂中有效成分的含量,与文献[1]方法结果基本吻合.     

Simple Chemical Route Synthesis of Fe2O3 Nanoparticles and its Application for Adsorptive Removal of Congo Red from Aqueous Media: Artificial Neural Network Modeling

Nanocrystalline Fe₂O₃ powder was synthesized by a simple chemical route involving FeCl₃ and NaOH. The Fe₂O₃ powder thus prepared was characterized using x-ray diffraction study, scanning electron microscopy, and Fourier transform infrared spectroscopy. The adsorption properties of crystalline Fe₂O₃ powder have been investigated with an aim to explore a possible low cost and efficient way to remove Congo red (CR) from waste water. Fe₂O₃ powder was found as an excellent adsorbent for CR from aqueous medium. Adsorption capacity as much as 203.66 mg g^?1 is reported at room temperature. Effect of different experimental parameters such as reaction pH, initial CR dye concentration, adsorbent dose, and reaction temperature were studied on adsorption capacity of Fe₂O₃ powder and modeled by artificial neural network (ANN). Optimal ANN structure (4–5–1) shows minimum mean squared error (MSE) of 0.00235 and determination coefficient (R²) of 0.991 with Levenberg–Marquardt algorithm. Isotherm analysis of experimental data exhibited better fit to the Langmuir isotherm. The adsorption process was found to follow second-order kinetics as depicted by the analysis of experimental results. Thermodynamic study shows that the adsorption process is endothermic, spontaneous, and thermodynamically favorable in the temperature range of 27°C to 60°C.     

Safer Pyrotechnic Obscurants Based on Phosphorus(V) Nitride

The potential of phosphorus(V) nitride, P₃N₅ , as a replacement for red phosphorus, P_R, in pyrotechnic obscurants has been theoretically and experimentally investigated. P₃N₅ can be safely mixed with KNO₃ and even KClO₃ and KClO₄ . The corresponding formulations are surprisingly insensitive to friction and only mildly impact‐sensitive. P₃N₅ /KNO₃ pyrolants with ξ=20–80 wt % P₃N₅ burn 200 times faster than the corresponding mixtures based on P_R and generate a dense smoke. Hence obscurants based on P₃N₅ /KNO₃ have a figure of merit that by far exceeds that of current state‐of‐the‐art P_R‐based obscurants. Furthermore, unlike P_R, which slowly degrades in moist air to phosphoric acids and phosphine (PH₃), P₃N₅ is stable under these conditions and does not produce any acids or PH₃ . P₃N₅ is hence a safe, stable, and powerful replacement for P_R for use in insensitive munitions.     

Determination of allura red using composites of water-dispersible reduced graphene oxide-loaded Au nanoparticles based on ionic liquid

A facile route for producing reduced graphene oxide (RGO)-loaded Au nanoparticles based on ionic liquids (IL) has been proposed, in which the as-prepared RGO can be dispersed stably in water. With the assistance of IL, Au nanoparticles were uniformly and densely absorbed on the surfaces of the IL functionalised reduced graphene oxide (IRGO), forming a new composite of IRGO/Au with high dispersibility. This IRGO/Au composite enhanced its electrochemical signal obviously in the measurement of allura red in foods and exhibited a wider linear response ranging from 0.297 (0.0006 μmol L^?1) to 99.3 μg L^?1 (0.2 μmol L^?1) with lower detection limit of 0.213 μg L^?1 (0.00043 μmol L^?1) at a signal-to-noise ratio of 3. To further study the practical applicability of the proposed sensor, the modified electrode was successfully applied to detect allura red in five kinds of common foods and the assay results were in a good agreement with the reference values detected by HPLC.     

New red-luminescent cadmium coordination polymers with 4-amino-2,1,3-benzothiadiazole

New polymeric cadmium complexes, α-[CdLCl₂]_n (1), [CdL₂Cl₂]_n (2) and β-[CdLCl₂]_n (3) (L = 4-amino-2,1,3-benzothiadiazole), were obtained as products of the reaction of CdCl₂ with L. The synthetic procedures allowing isolation of pure 1–3 were optimized. The structures of 1–3 were established by single-crystal X-ray diffraction and the compounds were characterized by UV–Vis and IR spectroscopy. In these compounds, L is either μ-bridging (1) or terminal (2 and 3). The UV–Vis spectra of the complexes in the solid state resemble that of free L. However, coordination of L leads to a significant shift of emission in photoluminescence spectra from yellow (free L) to red (1–3).     

A wine red copper(II) complex of a tetradentate nitrogen donor showing two-electron oxidation. Generation of a copper(II)-phosphine bond

Using the 1 : 2 condensate of benzil and 2-hydrazinopyridine as the ligand LH₂ (H: dissociable NH proton), the red complex Cu(LH₂)(ClO₄)₂ (1) was synthesized. The ligand also afforded the orange [Zn(LH₂)(OH₂)₂](ClO₄)₂ (2). The X-ray crystal structures of the ligand, 1 and 2 have been determined. The metals in 1 and 2 have octahedral N₄O₂ environments. 1 is paramagnetic with μ_eff of one unpaired electron (1.63 μ_B and displays an axial EPR spectrum in the solid state with <g> = 2.07, characteristic of a (d_x2_?y2)¹ ground state (g_|| > g_⊥; A_|| = 16 mT). In cyclic voltammetry, 1 displays a two-electron oxidation around 0.9 V versus NHE. The two-electron oxidized (coulometrically) solution of 1 (golden yellow) gives an EPR spectrum with <g> = 2.17 and g_|| < g_⊥. The reaction of PPh₃ with 1 yields the orange complex [Cu(LH₂)(PPh₃)](ClO₄)₂ (4). With the assumed chemical formula, the effective magnetization of 4 corresponds to one electron. Its EPR spectrum in the solid state is isotropic with g = 2.07. This g value yields a theoretical μ_eff of 1.80 μ_B at 298 K from Curie’s law, which matches very well with the experimental value of 1.89 μ_B at room temperature. Since single crystals of 4 could not be obtained, DFT calculations at the UBP86/6–311G(2d,p) level have been carried out and indicate that the cation in 4 is square pyramidal with the phosphine at the apex. The ease of the oxidation of the metal in 1 leads to the stabilization of the rare Cu(II)-P bond in 4.     

双向流固耦合作用下狭窄左冠状动脉内两相血流分析

基于血流与血管壁间双向流固耦合作用,将血液设为两相流体,运用计算流体力学方法对左冠状动脉内血流进行瞬态数值模拟.研究了一个心动周期内典型时刻下左冠状动脉内血流分布特性,并与Newton(牛顿)血液和两相血液模型对比,分析了两相血液和流固耦合作用对血流特性的影响.结果表明,左冠状动脉左回旋支远段和钝缘支近心端外侧分布了低速涡流区,该区域内壁面切应力和红细胞体积分数均较小,为动脉粥样硬化的形成与发展提供了合适的生理环境.左冠状动脉分叉处管壁形变量较大,引起管壁内膜功能发生紊乱,促进了粥样硬化斑块的形成.3种血液模型对比可知,红细胞的流动特性对血流速度及壁面切应力等血流动力学特性影响较大,双向流固耦合模型更符合真实的血液流动情况.     

新型聚中性红膜修饰碳糊电极的制备、表征及应用

运用一种新型的化学引发-电聚合方式将中性红膜固定到碳糊电极表面,制备出聚中性红薄膜修饰碳糊电极(PNR/CPE)。利用循环伏安法(CV)和交流阻抗谱(EIS)对修饰电极的电化学性能进行研究,借助于扫描电子显微镜(SEM)对修饰电极表面进行表征,并采用红外吸收光谱法(IR)和紫外可见吸收光谱法(UV-Vis)对PNR薄膜结构进行测试。结果表明,中性红成功地固定在碳糊电极表面,修饰电极的表面呈现特定的立体化结构,表面的电活性位点增多,电催化性能增大。在优化条件下,将该电极应用于鲱鱼精DNA(hs DNA)的检测,PNR电极上出现了1对较强的氧化还原峰,峰电流与其浓度在1.0×10~(-6)~8.0×10~(-5)mol/L范围内呈良好的线性关系,检出限为1.0×10~(-7)mol/L。     

Two new dammarane-type triterpene sapogenins from Chinese red ginseng

Two new dammarane-type triterpene sapogenins were isolated from the Chinese red ginseng. The new sapogenins were named as 24,26-dihydroxy-panaxdiol (1) and 24-hydroxy-panaxdiol (2). Their structures were elucidated by the combined analysis of NMR and mass spectrometry as 20(S),25(R)-epoxydammarane-3β,12β,24β,26-tetraol (1) and 20(S),25-epoxydammarane-3β,12β,24α-triol (2). The complete signal assignments of the two compounds were carried out by 2D NMR spectral and NOE differential spectroscopy analysis.