分数导数结合傅里叶最小二乘拟合处理含噪音的重迭信号

提出了一种含噪音重迭信号的综合处理方法 :先用傅里叶最小二乘法拟合噪音数据 ,然后对拟合后的信号求 2 .5次导数 ,在对模拟数据研究的基础上 ,讨论了求导后峰位漂移及其影响因素 ,给出了一个用于矫正峰位值的经验公式。用该方法对模拟和实际的紫外含噪音重迭信号进行处理 ,结果良好     

锐钛矿型纳米TiO2介孔粉体表面织构的研究

以硫酸钛和尿素为原料,聚乙二醇-1000为空间构造剂,104℃下经尿素水解均匀沉淀法研制颗粒分散均匀、粒径可控的高热稳定性锐钛矿型纳米TiO2介孔粉体,并对其晶相、颗粒大小、比表面积、形貌和孔道结构进行了表征.结果表明,未经任何热处理的TiO2粉体即为锐钛型晶相,颗粒为均匀分散的类球型颗粒,且颗粒间形成直通型的介孔孔道,其孔径在10～30nm之间.控制焙烧温度可以达到控制颗粒大小及形貌的目的,经850℃焙烧5h的样品仍保持锐钛矿型晶相,未出现向金红石型晶相转变的迹象.     

烷基和烷基苯磺酸钠系列的反相高效液相色谱法

用移动相中含有磷酸二氢钠的反相高效液相色谱法分析了烷基磺酸钠和烷基苯磺酸钠。对前者用电导检测器直接进行检测(无抑制柱),后者用紫外检测器检测。对几种商品十二烷基苯磺酸钠的组分和微乳液中十二烷基磺酸钠的含量进行了测定。得到了满意的结果。     

用钐和四氯化钛体系一锅法合成咪唑烷衍生物

在四氢呋喃溶液中,用Sm/TiCl4体系还原亚胺合成了咪唑烷衍生物.发现当没有促进剂1,2-二溴乙烷时,咪唑烷衍生物的产率小于20%,加入1,2-二溴乙烷后,产率大大提高.产物的结构通过IR,1HNMR和MS光谱确证.根据实验结果提出了一个可能的反应机理.     

固相萃取-气相色谱-质谱分析肉样中盐酸克伦特罗的残留量

建立了固相萃取 气相色谱 质谱联机分析肉样中盐酸克伦特罗残留量的方法。对盐酸克伦特罗在C1 8和离子交换固相萃取柱上的保留行为进行了研究 ,发现不同浓度盐酸克伦特罗的固相萃取回收率在 75 %～ 95 %之间 ;肉样中的加标回收率在 70 %～ 83 % ;相对标准偏差在 4 .95 %～ 1 3 .4 % ;最低检出限为 1 μg kg。盐酸克伦特罗的硅烷化产物 ,采用选择离子的模式进行检测 ( 86、2 4 3、2 62、2 77) ,衍生物的峰面积与样品浓度在0 .0 0 2 5 2～ 2 .0 2mg L范围内呈良好的线性关系 ,线性回归系数大于 0 .9999。     

Synthesis of Obyanamide, a Marine Cytotoxic Cyclic Depsipeptide

Obyanamide 1 is a cyclic depsipeptide that was recently isolated from the marine cyanobacterium Lyngbya confervoides by Moore and co-workers1. This compound displayed a potent inhibitory effect on both KB and LoVo cells in vitro. Several structural analog…     

ABS blends with phenoxy: morphology,thermal, mechanical and rheological properties

Blends of ABS (acrylonitrile–butadiene–styrene) with phenoxy(poly(hydroxyether bisphenol A)) were prepared using a Branender single screw extruder. Scanning and transmission electron micrographs (SEM, TEM) showed a typical two-phase morphology; particle-in-matrix (90/10) (ABS/phenoxy by weight), 70/30, 10/90), island/sea (30/70) and co-continuous (50/50) morphologies. The glass transition temperature (T_g) of SAN was almost unchanged in the blends, while the T_g of phenoxy increased by about 5 °C in the blends. The synergistic effect of tensile modulus and strength was noted in ABS-rich blends, where a drastic drop of ductility was seen, and the results were interpreted in terms of rubber particle migration form SAN to phenoxy phase, which was visualized by TEM. Melt viscosity showed yield in ABS-rich blends, and generally followed the log additivity.     

Single Atom Alloy Preparation and Applications in Heterogeneous Catalysis

There have been remarkable progresses in manipulating heterogeneous catalysts' nanostructures in the past decade. The concept of single atom alloy (SAA) was firstly proposed in 2012 when researchers successfully stabilized single Pd atoms on the Cu(111) surface. However, earlier work in 2009, which focused on replacing one Au atom with a Pd atom in thiolate protected Au₂₅ nanoclusters, could also be considered as the pioneer work of single atom alloy. Both kinds of single atom alloys exhibited the potential of maximum utilization of scarce elements and attractive catalytic performances. The well‐defined structures of SAA catalysts make accurate modeling possible, which further realizes the rational design of single atom alloy catalysts. In this review, we summarize the research trajectory of single atom alloys as well as recent achievements in this field. We also introduce several commonly adopted characterization methods for SAA catalysts such as scanning tunneling microscopy (STM), temperature programmed reaction (TPR), extended X‐ray absorption fine structure (EXAFS) spectra, matrix assisted laser desorption/ionization mass spectrum (MALDI‐MS) and differential pulse voltammetry (DPV). Through discussing recent progresses in SAA catalysts, we propose that future researches in this filed should be focused on exploring new kinds of metal nanocrystals and controlling the nanostructure of SAA even more precisely.     

Determination of Organophosphorus Pesticides in Soil by MMSPD-GC-NPD and Confirmation by GC-MS

A novel method, modified matrix solid-phase dispersion (MMSPD), has been developed for quantitative analysis of organophosphorus pesticide residues in soil. It was based on matrix solid-phase dispersion (MSPD) and continuous liquid-solid extraction (continuous LSE), using Florisil as sorbent and dichloromethane as the recycling solvent. Two soils with different texture and physicochemical properties were studied to validate the method. The effect of residence time of pesticides in soil was also studied. MMSPD was compared with MSPD and continuous LSE respectively. Determination was carried out by gas chromatography with nitrogen-phosphorus detection (GC-NPD). The method gave recoveries ranging from 72–105% with relative standard deviations (RSDs) lower than 15% for the pesticides studied. The limits of detection (LODs) ranged from 0.1 to 0.6 ng g⁻¹. Two pesticide residues have been detected in real soil samples from Fujian, China, using MMSPD. The pesticides were confirmed by gas chromatography-mass spectrometry (GC-MS) in a selected-ion monitoring (SIM) mode. Revised: 4 and 9 April 2006     

2-芳基硫杂脯氨酸结构特征的研究

对12种2-芳基硫杂脯氨酸进行了红外光谱和核磁共振谱测定,对其中两个化合物作了质谱测定。结果表明,这类化合物固态时主要以两性离子形式存在;有较强的分子离子峰,是一类较稳定的化合物。它们还存在一对非对映异构体,芳环上的取代基对芳环电子云密度的影响较大,而对四氢噻唑环的影响较小。