A Mizuno-Todd-Ye predictor-corrector infeasible-interior-point method for linear programming over symmetric cones

We propose a new general type of splitting methods for accretive operators in Banach spaces. We then give the sufficient conditions to guarantee the strong convergence. In the last section, we apply our results to the minimization optimization problem and the linear inverse problem including the numerical examples.     

原子吸收光谱法测定冬枣叶茶中的8种金属元素

采用湿法对沾化冬枣叶茶样进行消化处理,利用火焰原子吸收光谱法测定了茶中K、Na、Ca、Mg、Fe、Mn、Cu、Zn的含量.结果表明,该法的加标回收率为95.2%～104.2%,RSD≤3.35%.该法操作简单,结果准确,为开发和利用冬枣叶茶提供了一定的科学依据.     

相容次序矩阵PSD迭代法的收敛性

本文是在求解大型线性方程组Ax=b的系数矩阵A为(1,1)相容次序矩阵且其Jacobi迭代矩阵的特征值均为纯虚数或零的条件下,得到PSD迭代法收敛的充分必要性定理,并在特殊情况下得到了相应的最优参数.     

Can (H2O) n (n = 1–2) as effective catalysts in the CH2OO + H2S reaction under tropospheric conditions?

The addition reaction of CH₂OO?+?H₂S → HSCH₂OOH without and with catalyst X (X?=?H₂O and (H₂O)₂) has been investigated by CCSD(T)-F12a/VTZ-F12//B3LYP/aug-cc-pVTZ method and canonical variational transition state theory with small curvature tunneling correction. When H₂O was introduced in the CH₂OO?+?H₂S reaction, it not only acts as a catalyst for producing HSCH₂OOH, but also plays as a reactant to forming HOCH₂OOH. The formation channel of HSCH₂OOH is more important than the formation channel of HOCH₂OOH with its calculated rate constant larger by 11.0–43.2 times within the temperature 280–320?K. Then, (H₂O)₂ catalysed CH₂OO?+?H₂S → HSCH₂OOH reaction has been taken into account with its rate lower 1.9–4.2 times than the reaction of CH₂OO?+?H₂S → HSCH₂OOH with water. Also, CH₂OO?+?H₂S with H₂O cannot compete with the CH₂OO?+?H₂S reaction without water. This is different from CH₂OO?+?(H₂O)₂ reaction, which is about 4 orders of magnitude larger than the rate constant for CH₂OO?+?H₂O reaction. Such discrepancy is possible because C(CH₂OO)···O(H₂O) interaction has been enhanced more obviously by H₂O as compared to that of C(CH₂OO)···O(H₂S) interaction.     

Magnetic retrievable Ag/AgBr/ZnFe2O4 photocatalyst for efficient removal of organic pollutant under visible light

In the present work, a visible-light-driven Ag/AgBr/ZnFe₂O₄ photocatalyst has been successfully synthesized via a deposition–precipitation and photoreduction method. The crystal structure, chemical composition, morphology and optical properties of the as-prepared nanocomposites were characterized by X-ray diffraction spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscope, UV–vis diffuse reflectance spectroscopy and photoluminescence. The photocatalytic activities of the Ag/AgBr/ZnFe₂O₄ nanocomposites were evaluated through the photodegradation of gaseous toluene and methyl orange (MO) under visible light. The results revealed that the as-prepared Ag/AgBr/ZnFe₂O₄ nanocomposite exhibited excellent photocatalytic activity. The degrading efficiency of MO could still reach 90% after four cycles, and the Ag/AgBr/ZnFe₂O₄ nanocomposite could be recycled easily by a magnet. Additionally, the enhanced photocatalytic mechanism was discussed according to the trapping experiments, which indicated that the photo-generated holes (h⁺) and •O₂⁻ played important roles in photodegradation process. At last, a possible photocatalytic oxidation pathways of toluene was proposed based on the results of GC–MS. The Ag/AgBr/ZnFe₂O₄ composites showed potential application for efficient removal of organic pollutant.     

化学计量及分析测试技术发展动态

介绍国内外标准物质、分析测试技术的发展状况,重点介绍了美国、加拿大近几年在痕量有机分析、光谱化学分析、高准确度库仑分析、电感耦合等离子质谱、炉内原子化等离子体发射光谱等方面的研究动态。     

气相色谱-电子轰击离子源质谱法分析卷烟和烟叶中29种农药的残留

开展了卷烟和烟叶中有机氯、有机磷和拟除虫菊酯3类29种农药残留的气相色谱-电子轰击离子源质谱(GC-EI/MS)的分析方法研究。优化与选择了卷烟和烟叶样品的前处理条件,样品经正己烷-丙酮(体积比为1∶1)混合提取剂超声提取、Florisil硅土和中性氧化铝双净化剂固相萃取柱净化、二氯甲烷-正己烷(体积比为95∶5)混合洗脱剂洗脱和浓缩后,以磷酸三苯酯(TPP)为内标物,采用GC-EI/MS的选择离子监测方式(SIM)进行定性和定量分析。当样品的加标水平为20,50,100 μg/kg时,加标回收率为70%～110%,相对标准偏差在2%～8%之间;除了甲氰菊酯、氯菊酯和溴氰菊酯的方法检出限(LOD)分别为1.85,1.74与2.54 μg/kg外,其余的26种农药的LOD均小于0.8 μg/kg;线性范围为5.0～500.0 μg/kg,相关系数都大于等于0.9994。此分析方法已成功地应用于卷烟和烟叶样品中3类29种痕量农药残留的分析     

原子荧光光谱法研究贝壳堤岛贝壳沙中As的空间分布特征

用原子荧光光谱法测定了贝壳沙中As元素含量,研究了As在黄河三角洲贝壳堤岛贝壳沙中的空间分布规律,分析了贝壳沙中As与其他营养元素的相关性,并对影响其含量与空间分布的因素进行探讨。结果表明：贝壳沙样品中As的含量范围为0.78～8.76 mg·kg-1,平均值为3.11 mg·kg-1,整体上处于清洁的水平。贝壳沙中As含量有随剖面深度增加而增大的趋势,贝壳沙粒径大小也影响贝壳沙中As的含量,贝壳沙粒径越小,As含量越高,且不同粒径贝壳沙中As含量差异显著(p≤0.05)。贝壳沙中As与全磷(total phosphor,TP)和全钾(total potassium,TK)以及Cu, Zn, Mn均具有极显著的正相关关系,与全氮(total nitrogen,TN)和Fe的相关性不显著。综合分析认为,贝壳沙中As主要来自于风化后的贝壳沙对环境中As元素的吸附与固定而非贝壳形成过程中对该元素的富集作用。     

Self-assembled all-inclusive organic-inorganic nanoparticles enable cascade reaction for the detection of glucose

Traditional colorimetric glucose biosensor generally involves complex assay procedures. Free labile enzymes and peroxidase substrates are used separately for triggering a chromogenic reaction. These limits result in inferior enzyme stability and defective enzymatic catalytic efficiency, making it hard to routinely utilize them for the direct and fast test of glucose. In this work, we provide an all-inclusive substrates/enzymes nanoparticle employed 3,3′5,5′-tetramethylbenzidine (TMB) as chromogenic substrates and glucose oxidase (GOx)/horseradish peroxidase (HRP) as signal amplifier enzymes (TMB-GH NPs) by the molecule self-assembly technique. The “all-inclusive” nanoparticles can realize the tandem colorimetric reactions, and the oxidation product of TMB (ox-TMB) exhibits a strong NIR laser-driven photothermal effect, thus allowing quantitative photothermal detection of glucose. Owing to the restriction of the molecular motion of GOx, HRP, and TMB, the distance of mass transfer between substrates was shortened largely, leading to improved catalytic activity for glucose. Overall, our strategy will simplify the analysis procedure, furthermore, these integrated nanoparticles not only display higher stability and activity than that of the free GOx/HRP system and possesses an excellent performance for colorimetric and photothermal bioassay of glucose simultaneously. We believe that this unique technique will give good inspirations to develop simple and precise methods for bioassay.