人群重金属混合暴露与肝功能的关联研究

为探索单一及混合重金属暴露与肝功能的关联,为重金属暴露的健康效应提供证据,于2016—2018年在辽宁省的重金属污染区进行了横断面研究,共纳入了1 266名调查对象。收集了调查对象的血液样本和问卷信息,检测了血液样本中的铬(Cr)、镉(Cd)、钒(V)、锰(Mn)、铅(Pb)浓度用来代表调查对象的金属暴露,同时检测了血液样本中9种肝功能指标丙氨酸转氨酶(ALT)、天冬氨酸转氨酶(AST)、天冬氨酸转氨酶与丙氨酸转氨酶之比(AST/ALT)、白蛋白(ALB)、球蛋白(GLB)、白蛋白与球蛋白之比(ALB/GLB)、总蛋白(TP)、总胆红素(TBIL)、直接胆红素(DBIL)的水平。首先采用一般线性回归模型探索单一重金属暴露与肝功能标志物的关联,进一步采用加权分位数和(WQS)回归与Quantile g-computation模型分析重金属混合暴露与肝功能标志物的关联并计算每种金属的贡献占比。研究发现,重金属Cr、Cd、V、Mn、Pb单一及混合暴露均与AST/ALT、GLB、TBIL、DBIL存在正向关联,而与ALB、ALB/GLB、TP存在负向关联(P<0.05)。其中,V在混合重...     

潮州市西湖沉积物中金属元素的污染特性研究

用原子吸收分光光度法研究了潮州市西湖沉积物中的铜、锌、铅、镉、锰、镍、镁、钙等金属元素的含量及分布规律。结果表明,铜、铅、锌、镉和镍是主要的重金属污染物,沉积物中5种重金属的平均含量为:铜584.7 mg/kg,铅149.1 mg/kg,锌360.9 mg/kg,镉1.2 mg/kg,镍76.7 mg/kg,均高于我国土壤背景值。     

提取对中药材中金属元素含量的影响

中药材中常因含有一定量的重金属元素而使其质量受到影响。采用火焰原子吸收分光光度法测定几种常用中药材提取前后金属元素铜、铅、镉、锰、锌、铁的含量变化。结果表明,大部分中药材提取后金属元素含量均有不同程度的下降,这为去除中药材中的铅、铜等重金属提供了参考依据。     

微波消解-电感耦合等离子体质谱法测定粮食中12种重金属元素

粮食样品用硝酸-过氧化氢微波消解处理,采用电感耦合等离子体质谱法测定样品溶液中12种重金属元素(砷、铅、镉、硒、铬、铊、锰、镍、铜、铀、钴、钒)的含量。采用内标法消除基体的影响。方法的检出限(3S/N)在0.092~17.5pg·g-1之间。方法的加标回收率在88.1%~118%之间,相对标准偏差(n=5)小于6.0%。方法用于鸡肉标准物质(GBW 10018)中重金属含量的测定,测定值与认定值相符。     

ICP-AES同时测定碳酸钙中铁、锰、铅、镉、铬等10种金属元素

建立了电感耦合等离子体发射光谱法同时测定碳酸钙中铁、锰、铅、镉、铬、砷、汞、钡、镁、铜10种金属元素含量的分析方法。采用硝酸(1+4)溶解样品,在选定的仪器工作条件下直接测定。通过试验确定了各金属元素的分析谱线,对消解方法和消解液进行了探讨。10种金属元素的检出限为0.0018～0.0589μg/mL,加标回收率为91.80%～99.7%,测定结果的相对标准偏差为1.03%～4.85%(n=6)。该方法灵敏度高,适用于碳酸钙中多种重金属元素的同时测定。     

微波消解-电感耦合等离子体质谱法测定大气PM 2.5中金属元素

建立空气细颗粒物PM 2.5中主要金属元素含量的测定方法。滤膜样品经微波消解处理后,采用电感耦合等离子体质谱(ICP-MS)法测定锑、铝、砷、铍、镉、铬、汞、铅、锰、镍、硒、铊等12金属元素的含量。12种金属元素的相关系数都在0.99以上,检测限在0.08~2μg/L,精密度RSD在1.3%~2.2%,12种元素高、中、低3种浓度的加标回收率在89.5%~108.0%。ICPM S法操作简单、检出限低、准确性好,可为空气中金属元素的限量检测提供参考。     

雷公滕的药效及毒性与微量元素的研究

雷公藤是一种药效大、毒性也大的中药。研究了雷公藤的２８种无机元素，发现其有益元素铁、锰、锌、硒含量较高，其有害元素铅、砷、镉含量我高，与其药效和毒性一一相对应，雷公藤对风湿性关节炎、肾病、肝脏病、皮肤病的疗效，与铁、锰、锌、硒在人体中生物机理一致。雷公藤对消化道、心血管、肝脏、泌尿系统、造血系统的毒害作用，与铅、砷、镉在人体中的生物学效应一致。所以在使用雷公藤时，应考虑到微量元素作用，可提高雷公藤     

发铅与血铅的相关关系

头发中的铅除直接来源于血液外,体内和环境中的铅还通过纵向和横向多种通道渗入到头发结构中,头发和血液的铅动力学行为也不相同。发铅和血铅之间存在复杂的相关关系,铅摄入量的重大变化可削弱两者的关联强度,高铅暴露则加强两者的关联强度。骨铅的动员和释放,以及发样采集或预处理不当,均可使血铅或发铅值偏离真实,导致两者关联的不确定。血铅是近期铅暴露的量度指标,发铅可给出从前铅暴露或铅负荷的信息,后者更适合于人群铅中毒筛查或监测。     

雷公藤的药效及毒性与微量元素的研究

雷公藤是一种药效大、毒性也大的中药。研究了雷公藤的28种无机元素，发现其有益元素铁、锰、锌、硒含量较高．其有害元素铅、砷、镉含量也较高，与其药效和毒性一一相对应。雷公藤对风湿性关节炎、肾病、肝脏病、皮肤病的疗效．与铁、锰、锌、硒在人体中生物学机理一致。雷公藤对消比道、心血管、肝脏、泌尿系统、造血系统的毒害作用，与铅、砷、镉在人体中的生物学效应一致。所以在使用雷公藤时，应考虑到微量元素作用．可提高雷公藤的疗效，降低其毒性。     

植物类中药材及饮片中18种重金属及有害元素研究

建立植物类中药材及饮片中铅、镉、总砷、总汞、铜、锑、锡、铬、镍、钡、锰、铊、银、铍、镝、铝、硒、钼共18种重金属及有害元素含量的检测方法和限量。样品经微波消解处理后,采用电感耦合等离子体质谱法(ICP-MS)对100批植物类中药材中的重金属及有害元素进行测定和方法研究。各元素线性关系良好,相关系数(r)均大于0.999 5,方法检出限为0.000 22~0.023 0 mg/kg,回收率为90.2%~108.7%,相对标准偏差为1.8%~4.9%。该方法准确、简便、灵敏,可为植物类中药材中重金属及有害元素的检测与控制提供方法参考。     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.