氮化硼晶须的制备及其表征

利用先驱体转化法制备氮化硼晶须。利用三聚氰胺和硼酸为原料,利用水浴加热方法,生成一种BCN化合物先驱体。将该先驱体化合物在不同的温度段进行热处理后得到氮化硼晶须。借助SEM,FT-IR表征手段分析了不同温度热处理后晶须微观形态以及内部分子结构的变化,并用XRD,TEM等测试手段对最终晶须进行了表征。结果表明：所制备的氮...     

三聚氰胺的毒性毒理及检测最新进展

三聚氰胺是用途广泛的化工原料,含氮量高达66%,被不法分子作为蛋白替代品添加到乳品、饲料中,导致婴幼儿、宠物患泌尿结石甚至死亡。本文对三聚氰胺及其同系物的理化性质、代谢、毒性毒理、检测最新进展全面综述,并对其添加原因进行初步分析。     

A new approach to measure melamine, cyanuric acid, and melamine cyanurate using surface enhanced Raman spectroscopy coupled with gold nanosubstrates

Vibrational spectroscopic characteristics of melamine, cyanuric acid, and melamine cyanurate were measured using surface-enhanced Raman spectroscopy (SERS) coupled with gold nanosubstrates. Trace amounts of melamine and its analogues (cyanuric acid and melamine cyanurate) were characterized and quantified quickly and accurately by SERS in combination with partial least squares (PLS) analysis. Based on the relationship between the Raman intensity of the most prominent peak at around 676 cm⁻¹ and log values of melamine concentrations, the limit of detection (LOD) of SERS for melamine was estimated to be 2.6 × 10⁻⁷ mol L⁻¹ (∼33 ppb). An approximately 3 × 10⁴ fold of enhancement factor for SERS signals of melamine on gold nanosubstrates was obtained. This result was based upon the comparison of the peak at around 676 cm⁻¹ in the SERS spectra with that of normal Raman spectra of melamine in aqueous solutions. SERS spectra of cyanuric acid acquired from its solid form differ significantly from this compound in an aqueous solution, indicating a possible keto-enol isomerization reaction of cyanuric acid in water. When equal amounts of melamine and cyanuric acid were added together, spoke-like crystals of melamine cyanurate formed instantly, which could be measured and characterized by SERS. This study demonstrates that SERS could provide a fast and ultra-sensitive tool for detection and characterization of melamine and its derivative compounds in aqueous solutions.     

聚乙二醇对三聚氰胺甲醛树脂的改性研究

探讨了聚乙二醇对三聚氰胺甲醛树脂的改性机理,研究了物料配比,ｐＨ值等对改性三聚氰胺甲醛树脂的影响,改性后三聚氰胺甲醛树脂的中冲击强度提高了１倍以上。     

高压法三聚氰胺装置刺刀管式反应器运行工况浅析

介绍了高压法三聚氰胺装置刺刀管式反应器的结构和工作原理;剖析了刺刀管式反应器运行中存在的反应器管束结垢、进出口管线堵塞、外管管束受损、刺刀管结晶堵塞及结垢等问题;提出了刺刀管式反应器的生产操作要求及注意事项.结果表明,通过优化操作,刺刀管式反应器运行工况良好,可连续运行300天以上.     

食品中三聚氰胺检测方法的研究进展

本文综述了近年来食品中三聚氰胺的检测方法,主要包括气相色谱一质谱联用检测方法（GC—MS）、超高效液相色谱与质谱联用、固相萃取与高效液相色谱联用等,并指出气质联用（GC-MS）技术利用了色谱的高分离能力和质谱的高鉴别特性,可以对比较复杂的混合样品进行分离、定性、定量分析一次完成,是一种比较完美的现代分析方法。超高液相色谱一串联质谱法具有更快的分析速度、更高的分离能力和灵敏度,可以满足食品中三聚氰胺残留量的快速检测要求。     

MCA不同加料方式对尼龙66力学性能的影响

在双螺杆挤出改性工艺下,研究了不同的加料方式下三聚氰胺氰尿酸盐(MCA)填充尼龙66材料的弯曲和缺口冲击性能的变化。对材料进行弯曲、冲击试验测试。结果表明,侧喂料的弯曲模量比主喂料的结果低以及侧喂料的悬臂梁缺口冲击强度比主喂料的高。其主要原因是由于一定比例条件下主喂料的分散性较好,而MCA在加工过程以及最后改性材料中呈刚性片状颗粒的状态。因此MCA材料分散越是均匀材料的刚性越好。另外MCA粒子的粒径较大,因此材料在成型过程中分散越均匀,材料里面应力缺陷点越多,导致材料的冲击性能下降。     

基于纳米磁珠修饰印刷电极的牛奶中三聚氰胺检测安培免疫传感器

共固定氯代邻菲哕啉双核铜配合物(Cu2(phen)2Cl2(μ-Cl)2,简称CuzL)和包被三聚氰胺抗体(anti MA)的FbO4/Au胶(简称纳米磁珠)于丝网印刷电极(SPCE)表面,构建了一种测定牛奶中三聚氰胺(简称MA)含量的安培免疫传感器.当该传感器在含MA溶液中温育时,MA和同时加入的HRP标MA二抗(HRP-anti MA Ⅱ),与电极表面的anti MA形成三元免疫复合物.该复合物上的HRP能催化HzO2还原,并经过Cu2L传导在电极表面形成电流,电流强Ⅰ与MA浓度在0.5～40和60～100ng/mL范围内呈线性关系,检测限为0.25 ng/mL.在pH 6.2的PBS底液中,该传感器制作简单、可抛弃,对MA检测时间小于20 min,灵敏度为1μA·ng-1mL,明显高于酶联免疫吸附(ELISA)法;可实现牛奶中MA免分离现场分析.     

Fire resistant melamine based organic-geopolymer hybrid composites

Hybrid composite materials based on geopolymer and epoxy melamine resins have been designed to produce a novel material showing high compatibility between the organic and inorganic phases. This has been realized through a synthetic method based on the co-reticulation in mild condition of the two phases. These materials show good interpenetration of the resin into the inorganic matrix up to nanometric level and significantly improved mechanical properties in respect to un-modified geopolymer without compromising the good thermal stability and fire resistance typical of unmodified geopolymers. These properties make the novel materials very attractive for the realization of thermo-resistant and thermo-insulating panels.     

Residue analysis of melamine in milk products by micellar electrokinetic capillary chromatography with amperometric detection

A high-performance micellar electrokinetic capillary chromatography with amperometric detection (MECC–AD) method for the fast determination of melamine (MM), occasionally used to increase the apparent protein content of milk products, has been developed. Method development involved optimisation of the working electrode, the running buffer system and acidity, the concentration of sodium dodecyl sulphate (SDS), the separation voltage, the applied potential and the sample injection time. Under the optimum conditions, MM can be well separated from its co-existing interferences in real-world samples within 9 min at the separation voltage of 20 kV in a 8 mmol/L SDS/20 mmol/L H₃BO₃–Na₂B₄O₇ running buffer (pH 7.4). Satisfactory recovery (83.3–105.5%), repeatability of the peak current (3.2%) and migration time (3.8%), and the limit of detection (2.1 × 10⁻⁶ g/mL) for the method were achieved. This proposed procedure has been successfully used for the determination of MM in milk products.