凝胶渗透色谱和气相色谱-质谱法测定动物食品中27种有机氯和15种拟除虫菊酯类农药残留量

有机氯农药虽已被世界各国禁止使用,但由于其化学性质稳定和难以降解,在环境中仍然存在有机氯农药残留,并通过食物链的富集作用,造成对食物的污染.     

Enhancing Isolated Ti（ Ⅳ ） Framework Sites in HMS

IntroductionTitanium modified mesoporous molecular sieves,such as Ti-MCM-41[1—4], Ti-HMS[5], Ti-SBA15[6, 7], and their catalytic performances havebeen investigated. Framework substitution and graftingtechniques have been employed for the preparation ofti…     

Trap centers in Au-implanted MOS structures

Trap centers in the Si-SiO₂ interface region of MOS structures doped by ion implantation of gold have been investigated using constant capacitance deep level transient spectroscopy (CC-DLTS). Gold doses of 10¹²–3 × 10¹³ cm^–2 were implanted into the back surface of the wafers and were then redistributed during a diffusion anneal for 30 min at 1100° or 900° C. Three Au-related trap levels have been observed in the interface region, which were attributed to the Au-donor (E _v +0.35 eV), the Au-acceptor (E _v +0.53 eV), and the Au-Fe complex (E _v +0.45 eV). The trap concentration profiles show that the Si-SiO₂ interface affects the Au concentration in a depth range of 1 m from the interface and that gettering of Au occurs at the interface. The interface state density is independent of the Au concentration at the interface even for concentrations of 10¹⁵ cm^–3.     

Effect of NaOH and NaCl on the disodiumn-decane phosphonate micellar aggregation number

The diffusion coefficient of disodiumn-decane phosphonate micelles was studied by polarography at 25°C in NaCl and in NaOH solutions, and the size and aggregation number of the micelles was computed as a function of Na⁺ concentration. All other conditions being equal, the addition of NaCl produces micelles with an aggregation number one order of magnitude larger than the NaOH addition. This is due to the increase of the effective charge per micellized head group produced by the reaction of OH- with the hydrolized head groups which are mainly present as-PO₃H- in the micellar Stern layer.     

Zeolite content determination in kaolinic clays via thermal effects

For application in catalysis and adsorption processes, zeolites are synthesized on the surface of spray-dried kaolin microspheres. Various thermal effects are used for the rapid characterization of the zeolite type and content. From DTA measurements, the exothermic lattice break-down peak gives information on the zeolite type and the thermal stability of the sample. Measurements of the heats of immersion by a very simple and quick method allow conclusions about the type and the sorption properties of the zeolite part of the clay. The most precise method to estimate the zeolite content was a standardized technique of desorption and readsorption of water or organic compounds by means of a thermobalance.

---

Zusammenfassung Zur Anwendung in der Katalyse und bei Adsorptinsprozessen werden Zeolithe auf der Oberfläche sprüh-getrockneter Kaolin-Mikrokugeln eingesetzt. Verschiedene thermische Effekte werden zur schnellen Charakterisierung des Zeolith-Typs und -Gehalts genutzt. Der exotherme DTA-peak beim Gitterzusammenbruch liefert Informationen über Zeolith-Typ und thermische Stabilität der Probe. Eine sehr einfache Schnellmethode zur Messung der Immersionswärmen erlaubt Schlussfolgerungen über Typ und Sorptionseigenschaften des zeolithischen Anteils des Tons. Die genaueste Methode zur Bewertung des Zeolithgehalts war eine standardisierte thermogravimetrische Desorptions- und Readsorptions-Methode mit Wasser oder organiscen Verbindungen.

---

, , , . . , . , , . , .

     

Synthesis of Calix [4] resorcinarene Core Dendrimers with Peripheral Salicylideneimine Functional Groups

IntroductionOver the past two decades, dendrimers have at-tracted considerable attention because of their inherentnovel structural features and their potential applicationsin various scientific and industrial fields such as cataly-sis or newmaterials, and…     

水生动物及水产品中硫丹及其代谢物残留量的气相色谱-质谱测定

建立了水生动物及水产品中农药硫丹及其代谢物残留量的气相色谱-质谱(GC-MS)测定方法;样品经溶剂提取、凝胶层析柱净化;以氦气为载气,甲烷气为反应气,程序升温及负化学源(NCI)电离方式,采用气质联用仪在选择离子监测模式下进行快速测定,保留时间和离子相对丰度比定性、外标法定量;方法定量下限为0.004 mg/kg。在鳗鱼、泥鳅、鲶鱼、虾4种样品中添加不同浓度的硫丹时,其平均添加回收率在71%~87%之间,相对标准偏差(n=10)小于10%。     

Chalkogenolat-lonen und ihre Derivate. I. Darstellung und Eigenschaften salzartiger Chalkogenophenolate

Chalcogenolates and their Derivatives. I. Syntheses and Properties of Ionic Chalcogenophenolates The syntheses and properties of ionic chalcogenophenolates are described. Using liquid ammonia as solvent the alkali chalcogenophenolates M[EPh] (M = Na, K; E = Se, Te; Ph = C₆H₅) have been synthesized via reduction of the diphenyl dichalcogenides with alkali metals. Similarly, the tetraphenylphosphonium chalcogenophenolates [Ph₄P][EPh] (E = S, Se, Te) have been obtained by reacting alkali chalcogenophenolates with tetraphenylphosphonium chloride.     

介孔铁铝/蒙脱土复合材料：解离柱撑制备、结构及催化羟基化性能

利用极稀悬浮液中蒙脱土的解离作用并结合柱化技术过程，制备了介孔结构的铝铁/蒙脱土复合材料(Fe-Al/mmt)；并采用粉末X射线衍射、氮等温吸脱附、傅立叶红外光谱、紫外可见光漫反射光谱及苯酚催化羟基化反应表征了其结构和性能。结果显示，铁铝聚合前驱液中铁/铝比影响复合材料中蒙脱土的解离程度，且仅当低铁/铝比时(即Fe/(Fe+Al)物质的量的比介于0.05～0.3)，嵌入解离的蒙脱土片层间的混合铁铝物种呈现能耐温350 ℃的热稳定性；氮等温吸脱附分析反映出这种解离的蒙脱土堆积结构呈现介孔特征，孔径分布窄，介于2.0～2.3 nm；红外分析表明材料表面具有L酸和B酸位，并且L酸位量与嵌入解离的蒙脱土结构中的混合铁铝物种相关；由于结构中混合铁铝物种的存在及相应的Si-O → Fe、Al-O → Fe间的电子跃迁，Fe-Al/mmt材料在紫外区呈现宽泛的能量吸收特征。这些结果说明，由于混合铁铝物种嵌入于解离的蒙脱土片层堆积结构中，形成了“卡片屋”式介孔结构。实验条件下，Fe/(Fe+Al)物质的量的比为0.3的Fe-Al/mmt呈现较佳的催化羟基化性能，苯酚转化率为36.7%，二酚产物选择性32.3%；并且初步表明铝掺杂后，通过铁铝比和表面酸性的调整，材料的部分选择氧化性能可以得到改善。     

New sulfur-coordinating chiral ligands for the Tsuji—Trost reaction

The use of sulfur-coordinating chiral ligands in the palladium-catalyzed asymmetric Tsuji—Trost reaction is reviewed.