盐酸提取-液相色谱-原子荧光联用技术检测水产品中甲基汞等汞化合物

建立了HCl提取,高效液相色谱与原子荧光联用技术测定水产中无机汞、甲基汞、乙基汞形态的分析方法。对前处理方法和液相色谱的最佳参数进行优化,实验表明,3种汞化合物的线性范围为0~100μg/L,相关系数(r)均优于0.9990,检出限在0.3~0.6μg/L之间,汞化合物各形态的RSD均小于5%,加标回收率在78.8%~116.8%之间,标准物质(GBW10029),(GBW09101B)中汞形态的测定值均在标准值范围内,参加甲基汞FAPAS国际比对,测定结果的Z比分数为1.0,故本方法适用于水产品中汞化合物形态的分析测定。     

砷的代谢机制、毒性和生物监测

砷化合物是备受关注的一类污染物,特别是饮用水中的砷污染引发了全球性的健康问题.本文综述了近年来人们对砷的代谢机制、毒性和生物监测的研究进展.砷在生物体内的代谢过程十分复杂,在氧化还原酶和甲基转移酶的参与下,产生一系列的代谢产物和中间产物.其中,砷的原始摄入形态、代谢产物及中间产物由于不同的物理化学性质,体现了不同的毒性.人类和不同的动物由于不同的砷代谢机理和甲基化能力,也表现了对砷毒性抵抗能力的差异.在生物体内,一些砷化合物与生物蛋白相互作用,影响它们的存在形式、分布和传输,是砷的生物代谢和毒理研究中不可或缺的内容.生物监测是一种直接有效的污染物健康风险评估方法.在尿液、血液、唾液、头发和指甲中砷化合物直接反映了暴露主体的砷暴露程度,这5种生物介质作为砷暴露的生物标志物各有优缺点.在砷的研究中,代谢机制和毒性的研究可以帮助选择合适的生物监测方法,做出合理准确的健康风险评估.生物监测也可促进对砷的代谢机制和毒性的理解,推断可能的代谢途径,定量毒性剂量效应,两者相互依赖相互促进.     

Synthesis and textural evolution of alumina particles with mesoporous structures

Alumina particles with mesostructures were synthesized through a chemical precipitation method by using different inorganic aluminum salts followed by a heterogeneous azeotropic distillation and calcination process. The obtained mesoporous γ-alumina particles were systematically characterized by the X-ray diffraction, transmission electron microscopy and nitrogen adsorption-desorption measurement. Effects of the aluminum salt counter anion, pH value and the azeotropic distillation process on the structural or textural evolution of alumina particles were investigated. It is found that Cl⁻ in the reaction solution can restrain the textural evolution of the resultant precipitates into two-dimensional crystallized pseudoboehmite lamellae during the heterogeneous azeotropic distillation, and then transformed into γ-Al₂O₃ particles with mesostructures after further calcination at 1173 K, whereas coexisting SO₄²⁻ can promote above morphology evolution and then transformed into γ-Al₂O₃ nanofibers after calcination at 1173 K. Moreover nearly all materials retain relatively high specific surface areas larger than 100 m² g⁻¹ even after calcinations at 1173 K.     

Synthesis,Characterizations, Magnetism and Thermal Degradation of a 2‐Fold Interpenetrated 3D Cobalt‐Organic Framework

A new coordination polymer, [Co₂(L)₂(4,4′‐bipy)]_n·3nH₂O ( 1 ) based on 5‐(3‐methyl‐5‐phenyl‐4H‐1,2,4‐triazol‐4‐yl)isophthalic acid (H₂ L ) and 4,4′‐bipyridine (4,4′‐bipy) has been hydrothermally synthesized and characterized by single‐crystal X‐ray diffraction, XRPD, IR, and elemental analysis. Temperature‐dependent magnetic susceptibility and thermal degradation for 1 were also studied. The asymmetric unit of compound 1 consists of two crystallographically independent Co(II) ion, two L ^2? ligand, one 4,4′‐bipy ligand, and three lattice water molecules. The 2D triangle networks were linked by the bridging 4,4′‐bipy ligand to give rise to a 2‐fold interpenetrated 3D architecture. The simplest cyclic motif of the 2D networks is a triangle ring consisting of three Co(II) cations and three L ^2? ligands. So we can define Co(II) ions as 4‐connected nodes and the L ^2? ligands as 3‐connected nodes. Thus, the 3D structure can be described as a 2‐fold parallel interpenetrated ins InS 3,4‐conn topology.     

Color Point Tuning in Lu3−x−yMnxAl5−xSixO12:yCe3+ for White LEDs

A series of the solid‐solution phosphors Lu_3?x?yMn_xAl_5?xSi_xO₁₂:yCe³⁺ is synthesized by solid‐state reaction. The obtained phosphors possess the garnet structure and exhibit similar excitation properties as the phosphor Lu₃Al₅O₁₂:Ce³⁺, but with an effectively improved red component in the emission spectrum. This can be attributed to the energy transfer from Ce³⁺ to Mn²⁺. Our investigation reveals that electric dipole–quadrupole interactions dominate the energy‐transfer mechanism and that the critical distance determined by the spectral overlap method is about 9.21 Å. The color‐tunable emissions of the Lu_3?x?yMn_xAl_5?xSi_xO₁₂:yCe³⁺ phosphor as a function of Mn₃Al₂Si₃O₁₂ content are realized by continuously shifting the chromaticity coordinates from (0.354, 0.570) to (0.462, 0.494). They indicate that the obtained material may have potential application as a blue radiation‐converting phosphor for white LEDs with high‐quality white light.     

Rapid Sample Pretreatment,Identification and Determination of Active Constitutents in Water‐soluble Radix isatidis Extract via MAE,ESI‐MS and RODWs‐HPLC

In this study, we successfully studied water‐soluble extract from Radix isatidis. Optimized conditions of MAE were listed, the sample can be extracted completely in 10 minutes under microwave power of 400W and solid/liquid ratio of 1:80. Active compounds in water‐soluble extract from R. isatidis were identified with HPLC‐DAD/ESI‐MS, these compounds followed by cytidine, uridine, guanosine, (R,S)‐goitrin and adenosine. RODWs–HPLC as a new sensitive chromatography were also first proposed and investigated, we favoringly used this method for simultaneous determination of these active constitutents in water‐soluble R. isatidis extract. Chromatographic separation was performed on a Diamonsil C18 column (5 μm, 150 mm × 4.6 mm) with a mobile phase gradient consisting of methanol and water at a flow‐rate of 1.0 mL/min, detection wavelengths 240, 250, 260 and 270 nm, the retention times of the tested five compounds were about 4.2, 5.8, 11.1, 14.2 and 20.8 min respectively, the limits of detection were 15, 12, 20, 5.8 and 24 ng/mL for cytidine, uridine, guanosine, (R,S)‐goitrin and adenosine respectively, their linear ranges were between 0.045 and 350 μg/mL with correlation coefficient (R) of 0.9998‐0.9999. The relative standard deviations (RSDs) of intra‐day and inter‐day assays were 0.30‐2.36% and 0.86‐2.54% respectively. Extraction recoveries were 94.25‐106.21%. This novel analytical method was shown to be simple, low‐cost, sensitive and reliable for multiple components in complex or undeveloped materials via MAE, ESI‐MS and RODWs‐HPLC.     

A Conjugated Copolymer Bearing Imidazolium-based Ionic Liquid:Electrochemical Synthesis and Electrochromic Properties

An imidazolium-based ionic liquid(IL) modified triphenylamine derivative,namely 1-(4-((4-(diphenylamino)benzoyl) oxy)butyl)-3-methyl imidazole tetrafluoroborate(TPAC_6 IL-BF_4),was designed and synthesized,and further applied with 3,4-ethylene dioxythiophene(EDOT)to prepare conjugated copolymer P(EDOT:TPAC_6 IL-BF_4) via electrochemical polymerization.The cyclic voltammetry curves show that the copolymer P(EDOT:TPAC_6 IL-BF_4) possesses two pairs of redox peaks,which should be ascribed to the redox behaviors of EDOT and triphenylamine.The ultraviolet-visible(UV-Vis) absorption spectrum of P(EDOT:TPAC_6 IL-BF_4) exhibits one maximum absorption peak at 580 nm and a small shoulder characteristic peak at 385 nm under neutral state which are assigned to π-π~* conjugated structure of EDOT and triphenylamine.After being applied at the positive voltage,the copolymer color changes from dark blue to light blue,which is close to the color of poly(3,4-ethylenedioxythiophene)(PEDOT).Surprisingly,the copolymer P(EDOT:TPAC_6 IL-BF_4) shows shorter switching time of 0.37 s,0.30 s at 580 nm and 0.38 s,0.45 s at 1100 nm compared with PEDOT.It is more intriguing that the copolymer P(EDOT:TPAC_6 IL-BF_4) exhibits electrochromism even in free supporting electrolyte.The results confirm that the existence of imidazolium-based ionic liquid has an improvement on the ion diffusion properties and the switching time of conjugated polymer,which may provide a potential direction for the preparation of high-performance electrochromic materials.     

Inorganic–Organic Hybrid Molecular Clusters with Cu2I2 Rhomboid Dimer Core as Light-Emitting Coating Materials

Journal of Cluster Science - In this paper, a series of light-emitting copper(I) iodide inorganic–organic hybrid clusters has been synthesized, and they are 0D-Cu2I2(fmp)4 (1,...     

电化学部分氟化芳基研究进展

含氟芳香化合物具有生物活性好、稳定性高、易被生物体代谢等优点,在医药和农药领域有着广泛的用途.目前芳基部分氟化的方法主要分为依赖于氟化试剂的亲电氟化方法以及反应条件苛刻甚至需要过渡金属催化的亲核氟化方法,这些方法操作繁琐并且污染环境.电化学氟化将"电能"作为一种"强氧化剂"来实现氟化反应,是一种直接、绿色且温和的氟化手...     

热稳定单原子催化剂的理性构筑:从原子级结构到实际应用

80%以上的工业生产过程涉及催化,如化工生产、能源转换、制药和废物处理等等.催化剂的使用显著提高了生产效率,降低了生产成本,为国民经济、地球环境和人类文明的可持续发展做出了很大贡献.为了满足日益增长的生产需求和最大的经济效益,开发高效、稳定、低成本的新型催化剂已成为当务之急.金属中心负载在载体上的负载型金属催化剂因其较好的催化活性和相对较低的金属用量而受到广泛关注.研究发现,负载型结构可增强传热和传质并增加活性金属中心的分散度,从而影响催化性能.此外,负载金属的颗粒尺寸对催化剂的性能有很大影响.迄今为止,科学家们一直在通过减小金属颗粒尺寸和提高原子利用效率来提高催化剂的活性.原子级尺寸的颗粒通常表现出与大尺寸颗粒显着不同的物理和化学性质,而当活性位点的尺寸缩小到单个原子时,单原子催化剂的概念应运而生.对于单原子催化剂,金属原子中心通过配位被载体中的缺陷锚定,从而调整金属原子的电子云分布.这种配位调整使得单原子催化剂拥有与传统催化剂不同的性能.作为催化领域的新前沿,单原子催化剂已经在许多催化反应中表现出前所未有的活性和选择性.然而,许多报道的单原子催化剂在高温环境或长期催化应用中容易受到奥斯特瓦尔德熟化过程的影响,从而导致催化剂烧结和失活.而烧结的原因在于金属原子和载体之间较弱的相互作用.失活催化剂的再生和回收将大大增加工业生产的时间和经济成本.因此,开发具有优异热稳定性的单原子催化剂以满足工业需求是十分必要的.本综述首先总结了近年来关于热稳定型单原子催化剂合成方法的基础研究,并从原子尺度上分析了这些方法所构建的金属中心的结构形态和配位环境.此外,结合近些年的研究中新的表征技术与理论计算手段解释了热稳定性的来源.重点讨论了热稳定单原子催化剂的实际催化应用.分析了热稳定单原子催化剂在热催化应用中的独特作用机理、并尝试为确定催化过程中真正的活性中心以及通过原子级调控手段进行高活性热稳定单原子催化剂的合成提供理论指导.最后总结了热稳定单原子催化剂发展的主要问题,并简要分析了单原子催化领域的研究挑战和发展前景.