三嗪-吡唑钌配合物的合成、结构及光催化活性

光催化具有无污染、安全高效等优点,已成为环保领域的研究热点。 本文选择2,4-二(3,5-二甲基吡唑)-6-二乙基胺-1,3,5-三嗪(L₁)和2, 6-二[3-(5-甲基吡唑基)]吡啶(L₂)为配体、以RuCl₃为金属源,合成了3种配合物[Ru(L₁)Cl₃](1)、[Ru(L₂)₂]·Cl₃(2)和[Ru(L₂)₂]·(H₂BTC)·(HBTC)·H₂O(3),同时进行了IR、UV-Vis、TG及X射线衍射等表征,并对配合物在光催化降解罗丹明B方面进行了探讨,结果表明,配合物13均具有一定程度的光降解效果,降解效果分别为46.8%、44.7%和40.4%。 相同条件下,加入H₂O₂后的配合物13的降解效果比金属盐、配体及H₂O₂单独存在时的降解效果好。     

多功能纳米材料在肿瘤放疗增敏中的应用

放射治疗是利用放射线治疗肿瘤的一种局部治疗方法,目前已成为临床上最常用、最有效的恶性肿瘤治疗手段之一。但放射治疗仍存在辐射剂量高、对健康组织副作用大,特别是肿瘤细胞放射抵抗性强等缺点。随着纳米医学的发展,多功能纳米放疗增敏剂为增强肿瘤细胞放射敏感性、提高放疗效果提供了新机遇。本文结合纳米材料在放疗增敏中的优势和潜能,概括了纳米放疗增敏剂的主要类型和目前已进入临床实验的一些实例,简述了多功能纳米放疗增敏剂在肿瘤放射治疗中的应用,并归纳了纳米材料增敏放疗的主要途径和影响因素。最后总结和展望了多功能纳米放疗增敏剂面临的挑战和发展前景。     

A new streamline diffusion finite element method for the generalized Oseen problem

This paper aims to present a new streamline diffusion method with low order rectangular Bernardi-Raugel elements to solve the generalized Oseen equations. With the help of the Bramble-Hilbert lemma, the optimal errors of the velocity and pressure are estimated, which are independent of the considered parameter ε. With an interpolation postprocessing approach, the superconvergent error of the pressure is obtained. Finally,a numerical experiment is carried out to confirm the theoretical results.     

Density enhancement mechanism of upwind schemes for low Mach number flows

Many all-speed Roe schemes have been proposed to improve performance in terms of low speeds. Among them,the F-Roe and T-D-Roe schemes have been found to get incorrect density fluctuation in low Mach flows, which is expected to be with the square of Mach number. Asymptotic analysis presents the mechanism of how the density fluctuation problem relates to the incorrect order of terms in the energy equation UΔU. It is known that changing the upwind scheme coefficients of the pressure-difference dissipation term DPand the velocity-difference dissipation term in the momentum equation D~(ρU)to the order of O(c~(-1))and O(c~0) can improve the level of pressure and velocity accuracy at low speeds. This paper shows that corresponding changes in energy equation can also improve the density accuracy in low speeds. We apply this modification to a recently proposed scheme, TV-MAS, to get a new scheme,TV-MAS2. Unsteady Gresho vortex flow, double shear-layer flow, low Mach number flows over the inviscid cylinder, and NACA0012 airfoil show that energy equation modification in these schemes can obtain the expected square Ma scaling of density fluctuations, which is in good agreement with corresponding asymptotic analysis. Therefore, this density correction is expected to be widely implemented into allspeed compressible flow solvers.     

Improved synchronization criteria of Lur’e systems under sampled-data control

Nonlinear Dynamics - In this paper, we address the issue of $$\mathcal {H}_{\infty }$$ synchronization for two identical chaotic systems with time-varying delays and uncertainties under...     

基于液相色谱-串联质谱法的肉类特征肽段鉴别及掺假测定

建立了液相色谱-串联质谱技术鉴别肉类特征肽段及定量检测羊肉中常见外源肉掺假的方法。样品经蛋白质提取、胰蛋白酶水解和固相萃取小柱净化后,利用超高效液相色谱-四极杆/静电场轨道阱高分辨质谱（UPLC-Q/Exactive-HRMS）和Proteinpilot软件,实现蛋白质和多肽的鉴定;再通过基本局部比对搜索工具（BLAST）与Uniprot数据库对比分析,筛选出羊肉、鸭肉、猪肉和鸡肉的20个物种特征性多肽标志物;最后利用高效液相色谱-三重四极杆质谱（UPLC-QqQ-MS）系统对羊肉、鸭肉、猪肉和鸡肉的特征性多肽进行了验证和多反应监测（MRM）定量研究。将鸭肉、猪肉和鸡肉分别按照质量分数为1%、5%、10%、20%、50%的比例掺加到羊肉中,得到鸭肉最低掺假检出限为0.25%、猪肉最低掺假检出限为0.17%、鸡肉最低掺假检出限为0.10%。     

Synthesis and Thermodynamic Properties of M2L[M=Li,Na; L=3,6-Bis(1H-1,2,3,4-tetrazol-5-yl-amino)-1,2,4,5-tetrazine]

Two novel energetic alkalic metal salts of 3,6-bis(1H-1,2,3,4-tetrazol-5-yl-amino)-1,2,4,5-tetrazine (BTATz), Li₂(BTATz)·6H₂O(compound 1) and Na₂(BTATz)·2H₂O(compound 2), have been synthesized by the reaction of BTATz with lithium hydroxide or sodium hydroxide in dimethylsulfoxide(DMSO) solution, respectively, and their structures were characterized by means of elemental analysis and Fourier transform infrared spectrometry(FTIR). Moreover, the single-crystal structure of compound 1 was determined by single crystal X-ray diffraction. It crystallizes in the monoclinic space group P1/c. Furthermore, their thermal decomposition behaviors were investigated by means of differential scanning calorimetry(DSC) and thermogravimetry-differential thermal gravimetry(TG-DTG). The results show that the exothermic decomposition peak temperatures for compounds 1 and 2 were 642.65 and 644.46 K, respectively, and the kinetic equations of the main exothermic decomposition were also derived from non-isothermal method. Additionally, the thermal safety of the two compounds was evaluated by calculating self-accelerating decomposition temperature(T_SADT) and critical temperature of thermal explosion(T_b). The results(the T_SADT and T_b values are 605.43 and 635.69 K for compound 1; 607.38 and 638.96 K for compound 2) reveal that the two compounds exhibit better thermal safety than BTATz.     

Improving Catalytic Performance of Burkholderiacepacia Lipase by Chemical Modification with Functional Ionic Liquids

Various imidazolium and choline-based functional ionic liquids(ILs) comprising different cations and anions were grafted onto Burkholderiacepacia lipase(BCL) through surface amino acids coupling. The catalytic activity, thermostability, organic solvent tolerance and adaptability to temperature and pH changes of the modified BCL were then evaluated in olive oil hydrolysis reaction. The results showed that different combinations of cations and anions in ILs had important influence on the catalytic performance of the modified lipases. BCL modified with IL[Choline] [H₂PO₄] was the most improved lipase, in which increases by 1.2 folds in relative activity, 2.5 folds in typical proton solvent(10% methanol, volume fraction), and 1.4 folds in thermostability(after incubation at 70℃ for 2 h) were achieved in relative toits native form. BCL modified with[HOOCEPEG₃₅₀IM] [BF₄] had higher optimal tempe-rature and pH, and better thermosability compared with the native and other modified BCLs. The conformational changes of BCLs were also confirmed by fluorescence spectroscopy and circular dichroism spectroscopy.     

One-step Construction of Xanthone Scaffold Assisted by Microwave Irradiation to Optimize the Synthesis of DMXAA

An efficient and concise synthesis of 5,6-dimethylxanthenone-4-acetic acid(DMXAA) was developed. The overall yield of this 3-step procedure was 82%. The key reaction is the one-step construction of xanthone scaffold between 2,5-dibromo-3,4-dimethylbenzoic acid and 2-hydroxyphenyl-acetic acid assisted by microwave irradiation.     

Synthesis of Highly Sensitive Fluorescent Probe Based on Tetrasubstituted Imidazole and Its Application for Selective Detection of Ag+ Ion in Aqueous Media

A small molecule fluorescent probe, 4-[2-(4-chlorophenyl)-4,5-diphenyl-1H-imidazol-1-yl]aniline(L) for detecting Ag⁺ ion was gently synthesized via one-pot multi-component reaction catalyzed by H₃[PW₁₂O₄₀] under solvent-free microwave irradiation. When the concentration of Ag⁺ ion changed from 0 to 8.0×10⁻⁶ mol/L in the solution of H₂O/CH₃OH(19:1, volume ratio), the fluorescence emission spectrum was blue-shifted and accompanied by a gradual increase in fluorescence intensity with a low detection limit of 3.0×10⁻¹¹ mol/L. Moreover, UV-Vis absorption titration experiment demonstrated a 1:1 stoichiometric ratio and an association constant of (9.95±0.44)×10⁵ L/mol between probe L and Ag⁺ ion, and thus their complexation mechanism was also proposed and verified. More importantly, this fluorescent probe was remarkably specific for Ag⁺ ion under the interference of other metal ions and exhibited a wide pH application range of 4.0-8.0. Additionally, preliminary application of this probe was also carried out and satisfactory results were shown.