Analysis of residues of 81 pesticides on ginkgo leaves using QuEChERS sample preparation and gas chromatography/mass spectrometry

Pesticide residues on Ginkgo leaves are a safety concern. A fast and reliable method was developed for the analysis of 81 pesticides on Ginkgo leaves, which are pharmaceutically valuable. The method consists of a modified Quick, Easy, Cheap, Effective, Rugged, and Safe sample preparation method and GC/MS detection. Five sorbents (graphitized carbon black, primary secondary amine, amino, alumina, and Florisil) and two solvents (toluene and hexane) were optimized for the cleanup procedure. The LOD and LOQ ranged from 0.05 to 17.6 and 0.16 to 58.8 microg/kg, respectively. A majority of the pesticides (86-94%) gave satisfactory recoveries (70-110%), and 1-6% of the substances gave recoveries higher than 110% of the spiked concentration (n = 5) at 0.02, 0.05, and 0.1 mg/kg. Less than 5% of the substances showed recoveries lower than 70%. The method was proven to be repeatable with RSDs lower than 20%.     

Inventory competition for newsvendors under the objective of profit satisficing

Inventory competition for newsvendors (NVs) has been studied extensively under the objective of expected profit maximization which is based on risk neutrality. In this paper, we study this classic problem under the objective of profit satisficing which is based on downside-risk aversion. Consistent with prior literature, we consider two possible scenarios. In the first scenario, each NV’s demand depends on the stocking levels of all NVs other than herself. In this scenario, we show that there is a unique Nash equilibrium where all NVs optimally order as if they were independent. In the second scenario, each NV’s demand depends on the stocking levels of all NVs including herself. We prove the existence of Nash equilibrium for both additive and multiplicative forms of demands. As a special case, we also study symmetrical NVs under the proportional allocation model. We show that at equilibrium, if the number of NVs exceeds a threshold, the market becomes highly competitive.     

Sensitive detection of esculetin based on a CdSe nanoparticles-decorated poly(diallyldimethylammonium chloride)-functionalized graphene nanocomposite film

An electrochemical sensor based on a CdSe nanoparticles (NPs)-decorated poly(diallyldimethylammonium chloride) (PDDA)-functionalized graphene (CdSe-PDDA-G) nanocomposite was fabricated for the sensitive detection of esculetin. The nanocomposite was characterized by X-ray diffraction (XRD), ultraviolet/visible spectra (UV-vis) and transmission electron microscopy (TEM). Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were used to investigate the electrochemical behaviors of esculetin on the CdSe-PDDA-G composite film-modified glassy carbon electrode (GCE). The experimental results indicated that the incorporation of CdSe NPs with PDDA-G greatly enhanced the electrochemical response of esculetin. This electrochemical sensor displayed satisfactory analytical performance for esculetin detection over a range from 1.0 × 10(-8) to 5.0 × 10(-5) mol L(-1) with a detection limit of 4.0 × 10(-9) mol L(-1) (S/N = 3). Moreover, the sensor also exhibited good reproducibility and stability, and could be used for the detection of esculetin in real samples with satisfactory results.     

A novel method for dynamic investigations of photoinduced electron transport using functionalized-porphyrin at ITO/liquid interface

A new scanning electrochemical microscopy (SECM) model provided a two-dimensional quantitative analysis on a heterogeneous electron transport (ET) process of a functionalized porpyrin by photoinduced ET at the ITO/liquid interface. The basic features of oxidized porphyrin under light source were recorded by feedback approach curves within the framework of the bimolecular ET mechanisms.     

光场二阶相干函数的实验研究

从理论和实验上给出研究光场二阶相干函数的新方法，并能够应用皮秒或亚皮秒范围的超快现象测量中。     

CdS半导体纳米晶体高强度激发下光谱特性研究

CdS半导体微晶作为代表性介观材料(mesoscopic material)其光学吸收和发光与量子尺寸效应的关系已经得到广泛研究[1-4],发现随着CdS微晶尺寸减小,CdS本征吸收和发射带呈现显著蓝移.Rossetti等人[3]和Y.Wang等人[4]分别通过对溶胶、沸石、聚合物和玻璃中CdS纳米晶体的光致发光测量研究了发光来源以及发光与尺寸的关系,确定了两个宽带发光分别属于带隙发光(350-500nm)和表面态或缺陷发光(500-700nm).本文首次报道了利用溶胶凝胶方法制备的钠硼硅中纳米尺寸CdS晶体高激发功率条件下的发光光谱测量结果,观察到随激发功率增加发光光谱兰移和线宽明显宽化,讨论了其物理机制.     

掺杂Y3+和Gd3+的 Phen-Eu(Ⅲ)二元固体配合物的红外及荧光光谱研究

合成了掺杂Y^3 和Gd^3 的Phen-Eu(Ⅲ）二元固体配合物，确定了它们的组成，测定了固体配合物的红外光谱和荧光光谱，并首次探讨了掺杂Y^3 和Gd^3 的Phen-Eu(Ⅲ）二元固体配合物荧光强度的影响。     

铕（Ⅲ）与HTTA及Phen类衍生物的三元固体配合物的红外及荧光光谱研究

合成了铕（Ⅲ）与２－噻吩甲酰三氟丙酮（ＨＴＴＡ）和１，１０－邻菲罗啉（Ｐｈｅｎ）及其衍生物的三元固体配合物，研究了它们的红外光谱和荧光光谱。     

新型永久光谱烧孔材料及机理研究

利用永久光谱烧孔(Persistent spectral hole burning(PSHB))可使光学信息存储密度提高三个数量级以上[1].这一重要应用前景激励科学家探索和寻求具有较高的非均匀(inhomogeneous)线宽与均匀(homogeneous)线宽之比(决定存储密度)和可擦除性(erasable)新型光谱烧孔材料.有机材料易于进行分子设计和组装,是较理想的光存储(optical storage)材料.