Determination of the n‐octanol/water partition coefficients of weakly ionizable basic compounds by reversed‐phase high‐performance liquid chromatography with neutral model compounds

A strategy to utilize neutral model compounds for lipophilicity measurement of ionizable basic compounds by reversed‐phase high‐performance liquid chromatography is proposed in this paper. The applicability of the novel protocol was justified by theoretical derivation. Meanwhile, the linear relationships between logarithm of apparent n‐octanol/water partition coefficients (logK_ow′′) and logarithm of retention factors corresponding to the 100% aqueous fraction of mobile phase (logk_w) were established for a basic training set, a neutral training set and a mixed training set of these two. As proved in theory, the good linearity and external validation results indicated that the logK_ow′′–logk_w relationships obtained from a neutral model training set were always reliable regardless of mobile phase pH. Afterwards, the above relationships were adopted to determine the logK_ow of harmaline, a weakly dissociable alkaloid. As far as we know, this is the first report on experimental logK_ow data for harmaline (logK_ow = 2.28 ± 0.08). Introducing neutral compounds into a basic model training set or using neutral model compounds alone is recommended to measure the lipophilicity of weakly ionizable basic compounds especially those with high hydrophobicity for the advantages of more suitable model compound choices and convenient mobile phase pH control.     

聚氰基丙烯酸乙酯空心纳米纤维的制备

通过溶液聚合法制备了具有空心结构的聚氰基丙烯酸乙酯纳米纤维,纤维直径为50~100 nm.研究了3种溶液体系对形成聚氰基丙烯酸乙酯纳米纤维形貌与直径的影响,并探讨了其形成机理.通过调控溶液体系内外环境可得到不同形貌的聚合物纤维,且纤维表面表现出疏水性质.该方法适用于平整且具有粗糙结构的表面.所形成的聚氰基丙烯酸乙酯纳米纤维涂层可用于基底的疏水改性.     

粉末压片—X射线荧光光谱法测定土壤中的铜铅锌砷锑钴铬镍等重金属元素

采用粉末压片法制样,使用ZSX PrimusⅡ型X射线荧光光谱仪,对土壤样品中与生命健康和环境污染有直接影响的重金属元素Cu、Pb、Zn、As、Sb、Co、Cr、Ni进行同时测定.选用土壤国家标准物质、以国家标准物质为基体自制校准物质绘制标准曲线,解决了相关标准不足的问题,拓宽了元素测定范围(10~20 000μg/g),重点探讨了As、Sb的测量条件.虽然As、Sb的检出限和准确测定下限较高,但对于土壤质量的评价有重要的参考意义.方法快速、简便、准确.     

Simultaneous determination of chlorpyrifos and 3,5,6-trichloro-2-pyridinol in duck muscle by modified QuEChERS coupled to gas chromatography tandem mass spectrometry (GC-MS/MS)

A rapid, specific, and sensitive method based on modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) coupled to gas chromatography tandem mass spectrometry (GC-MS/MS) was developed and validated for simultaneous determination of chlorpyrifos (CP) and its metabolite 3,5,6-trichloro-2-pyridinol (TCP) in duck muscle. The residues of CP and TCP were extracted by acidified acetonitrile. The fat layer of the extract was removed under ?20 °C, then the organic layer was evaporated. The analytes were derivatized by N-(tert-butyldimethylsilyl)-N-methyltrifluoroacetamide (MTBSTFA) and cleaned up by a mixture of 150 mg MgSO₄, 25 mg graphitized carbon black (GCB), and 50 mg N-propylethylenediamine (PSA) to remove interference. The final extract was analyzed by GC-MS/MS. Recovery values at the spiking concentrations ranged from 86.2 to 92.3 % for CP and from 74.8 to 81.8 % for TCP, with relative standard deviations (RSDs) lower than 9.5 and 12.3, respectively. The correlation coefficients of CP (from 2 to 2,000 μg/kg) and TCP (from 1 to 1,000 μg/kg) were equal to or higher than 0.998. The limits of detection (LODs) were 0.3 and 0.15 μg/kg, and the limits of quantification (LOQs) were 1.0 and 0.5 μg/kg for CP and TCP in duck muscle, respectively. The average intra- and inter-day accuracy ranged from 84.6 to 91.2 % for CP and 75.6 to 82.3 % for TCP, and the intra- and inter-day precisions were from 5.8 to 8.2 % for CP and 6.5 to 11.9 % for TCP. Furthermore, the CP and TCP residues in duck muscle samples were detected for dietary risk assessment using the validated method.

基于Schiff base配体及吡啶环的铜(Ⅱ)、镍(Ⅱ)配合物构筑、表征与热稳定性

用缓慢挥发法和水热法分别合成了镍配合物NiLPy（L=5-溴-2-羟基苯基苯基酮-4-甲氧基苯甲酰腙,Py=吡啶）（1）及铜配合物Cu（babh）₂（Py）（Hbabh=苯亚甲基苯乙酮苯甲酰腙,Py=吡啶）（2）,并用元素分析、红外、热重及X-射线单晶衍射对其进行了表征。晶体结构表明：1属三斜晶系,P1空间群;2属单斜晶系,Pc空间群。化合物1和2分别通过分子间弱的C-H…π与C-H…N作用堆积形成二维片状超分子层。热重分析表明配合物1和2分别处于225和170℃以下温度时很稳定。     

基于角度度量法的混纺纤维定量检测

采用“基于角度度量的多变量回归方法”对维纶和腈纶混纺纤维各组分含量进行检测,并与直接用偏最小二乘法（PLS）对混和纤维的预测结果作对比。实验结果显示,PLS法对维纶和腈纶预测值与实际值的线性相关系数r均为0．9457,标准偏差为6．0906,均方根误差为6．9948。角度度量法对维纶预测值与实际值的线性相关系数r为0．9990,标准偏差为0．8929,均方根误差为2．1896;对腈纶预测值与实际值的线性相关系数r为0．9928,标准偏差为2．1896,均方根误差为3．9493。实验证明,角度度量法比PLS法更能准确表达定量关系,角度度量法可以显著降低分析操作对环境的要求,满足了近红外光谱在混纺纤维定量分析上的要求。     

负载型CuO/TiO2催化剂催化CO2加氢制甲醇

采用浸渍法制备了CuO/TiO₂负载型催化剂,并将其用于CO₂加氢制甲醇反应。重点考察了铜的负载量对催化剂性能的影响,并对其物化性能和催化性能之间的关系进行了讨论。结果发现,随着铜负载量的增加,催化剂中金属铜的比表面先增加后减小,当铜的负载量为10%（质量百分数）时达到最大值。催化剂的表面碱性位数量随铜含量的增加持续减小,中等碱位和强碱位的强度下降。当铜的负载量不高于10%时,CO₂的转化率与铜的比表面积呈线性关系。甲醇选择性与催化剂的表面碱位性质有关,过强的碱性位会降低甲醇选择性。     

碳化硅和碳化硼在电催化中的应用

燃料电池是具有广泛应用前景的新能源技术。碳载铂基催化剂（Pt/C）是最常用的燃料电池电极催化剂,不过Pt/C稳定性较差、且成本高昂,严重限制了燃料电池的规模化应用。共价型碳化物碳化硅和碳化硼,由于具有极强的共价键,其物化稳定性优异,成为制备高稳定性、低成本的燃料电池催化剂的重要基础材料。本文总结了相关研究成果,介绍了碳化硅和碳化硼的独特优势,讨论了相关研究的发展方向。     

铕配合物共掺杂电致发光器件效率滚降的延缓

将Alq₃[tris(8-hydroxyquinoline)aluminium]和Eu(TTA)₃phen(TTA=thenoyltrifluoroacetone,phen=1,10-phenanthroline)共掺杂进入主体材料CBP(4,4’-N,N’-dicarbazole-biphenyl)中,我们制作并研究了一系列电致发光器件。经过优化Alq₃的掺杂浓度,在不改变色纯度的情况下,器件的效率滚降被大幅降低并获得了近乎加倍的最大亮度。发光层中的Alq₃分子不仅促进了电子的注入和传输,还延缓了空穴的传输。借助电致发光光谱,我们证实Alq₃分子作为阶梯加速空穴从CBP分子到Eu(TTA)₃phen分子的迁移,从而促进了电子和空穴在Eu(TTA)₃phen分子上的平衡。因此,我们认为器件的效率滚降受到抑制的原因有两点：一是复合区间的加宽,二是Eu(TTA)₃phen分子上空穴和电子的分布更加平衡。     

DNA拓扑异构酶抑制剂

DNA拓扑异构酶是一种广泛存在于真核细胞和原核细胞中的重要生物酶,对DNA转录、复制、染色体分离及基因表达等过程中的DNA拓扑结构起着重要的调控作用。研究发现,与正常细胞不同,DNA拓扑异构酶在肿瘤细胞中表现出不受其他因素影响的高水平表达,而许多抗肿瘤药物的作用机制也与DNA拓扑异构酶密切相关,因此它作为抗肿瘤药物的重要靶点引起了研究者的广泛关注。本文对DNA拓扑异构酶的结构、分类及生物功能进行了简要的归纳,总结了近年来DNA拓扑异构酶抑制剂的研究进展,并重点对金属配合物作为DNA拓扑异构酶抑制剂的研究现状进行了详细的介绍。