硫化镉量子点-硫酸依替米星体系的共振瑞利散射和共振非线性散射光谱研究及其分析应用

在弱酸介质中,硫化镉量子点(CdS-QDs)与硫酸依替米星(ETM)在静电引力和疏水作用力下,形成粒径更大的聚集体,导致共振瑞利散射(RRS)、二级散射(SOS)和倍频散射(FDS)显著增强,其最大散射峰分别位于310 nm(RRS),568 nm(SOS),320 nm(FDS).在一定范围内ETM浓度与三种散射增强程度(△I)成正比,可用于ETM的测定,其中RRS的灵敏度最高,其检出限(3σ)为1.6 ng/mL.考察了共存离子的影响,表明方法有良好的选择性.据此发展了以CdS-QDs作探针,高灵敏、简便测定ETM的共振瑞利散射新方法,用于人血清和尿样中ETM的测定,平均回收率在94.5%～113.7%之间.

Abstract：

In a medium of pH = 5.6, CdS quantum dots could react with etimicin sulfate to form larger aggregates by virtue of electrostatic attraction and the hydrophobic force, which resulted in a great enhancement in resonance Rayleigh scattering (RRS) and resonance non-linear scattering such as second-order scattering (SOS) and frequency doubling scattering (FDS). The maximum scattering peaks were located at 310 nm for RRS, 568 nm for SOS and 320 nm for FDS. The enhancements of scattering intensity (△I) were directly proportional to the concentration of etimicin sulfate (ETM) within a certain range. Of the three methods, RRS had the highest sensitivity, its detection limit (3σ) being 1.6 ng/mL. An examination of the effects of coexisting substances showed that the method had good selectivity. Based on these results, a new method, highly sensitive and simple, was developed, which can be used to determinate ETM by CdS-QDs as a probe. The recovery for the determination of ETM in human serum and uric samples was in the range of 94. 5%-113.7%.     

共振瑞利散射法测定水产品中孔雀石绿

在pH=4.4的HC1-NaAc缓冲介质中,孔雀石绿(MG)以及钨酸盐溶液自身的共振瑞利散射(RRS)均十分微弱.但是当MG染料阳离子与钨酸根(WO42-)形成离子缔合物时,RRS急剧增强,并出现新的RRS光谱,其RRS峰分别位于339 nm,451 nm和591 nm处.在最大散射波长339 nm处.孔雀石绿浓度在0.060～2.8 μg/mL范围与散射增强(ΔⅠ)呈良好线性关系,因此可用于痕量孔雀石绿的测定.方法灵敏度高,检出限为18.1 ng/mL.本法用于鱼肉中孔雀石绿残留量的测定,结果满意.

Abstract：

In an experiment reported in this paper, the resonance Rayleigh scattering (RRS) of malachite green (MG) or tungstate anion was very weak in pH 4.4 HC1-NaAc buffer medium, but when MG cation reacted with WO42- anion to form an ion association complex, its RRS dramatically increased and a new RRS spectrum appeared with the RRS peaks at 339 nm, 591 nm and 451 nm. The intensity of RRS (ΔⅠ)was directly proportional to the concentration of malachite green in the range of 0.06-2.78 μg/mL at the maximum scattering peak of 339 nm. The method was shown to be sensitive and the detection limit for MG was 18.1 ng/mL. Thus a new method for the determination of MG was developed. When applied to the determination of malachite green residues in the flesh of fish, this method gave satisfactory results similar to those of the HPLC method.     

CdTe量子点作探针共振瑞利散射法测定肝素钠

在水相中低温条件下制备了巯基乙胺稳定的CdTe量子点(CdTe QDs).基于肝素钠(Heparin)对巯基乙胺稳定的CdTe QDs共振瑞利散射(RRS)的增强作用,同时二级散射(SOS)和倍频散射(FDS)也相应增强,建立了一种快速、简便、定量测定肝素的新方法,同时讨论了最佳反应条件和影响因素,以RRS为例,在311 nm处,RRS的光谱强度与肝素钠的质量浓度c/(I-I_0)有良好的线性关系(r=0.999 1),线性范围13.5～1000 ng/mL,检出限(3σ)为4.04 ng/mL.可用于血样中肝素钠的测定.

Abstract：

Aqueous cysteamine-capped CdTe quantum dots(QDs) were prepared under low temperature.A simple and rapid quantitative method for heparin determination was proposed, based on the fact that hepa-tin can enhance CdTe QDs resonance Rayleigh scattering (RRS) and the intensities of second-order scatter-ing (SOS) and frequency-doubling scattering (FDS).Factors affecting RRS for detecting heparin with cys-teamine-capped CdTe QDs were studied.At 311 nm, the RRS calibration plot of C/(I-I_0) with concen-tration of heparin was linear in the range of 13.5-1 000 ng/mL with a correlation coefficient of 0.999.The limit of detection (30) was 4.04 ng/mL.     

牛血清白蛋白共振瑞利散射和共振非线性散射法测定硫酸软骨素

在pH=2.8～4.0的BR缓冲溶液中,硫酸软骨素(CS)由于磺酸基离解而成为带多个负电荷的大阴离子,而低于其等电点(pI=4.7)的牛血清白蛋白(BSA)则以带正电荷的大阳离子存在,两者之间可结合形成复合物.此时将引起共振瑞利散射(RRS)显著增强,并产生新的RRS光谱,其最大散射波长位于304 nm处.与此同时,它的二级散射(SOS)和倍频散射(FDS)也明显增强,且最大SOS和FDS分别位于471 nm和292 nm.散射增强的强度(△I_(RRS)、△I_(SOS)和△I_(FDS)与CS浓度在一定范围内成正比,可用于CS的定量测定.对于CS的检出限(3σ)分别为2.0 ng/mL(RRS),2.9 ng/mL(SOS)和13.2 ng/mL(FDS).研究了适宜的反应条件,考察了共存物质的影响,表明方法有较好的选择性,可用于市售滴眼液中硫酸软骨素含量的测定.

Abstract：

In a Britton-Robinson (BR) buffer solution of pH 2.8--4.0, chondroitin sulfate (CS), which carries negative charge by the ionization of sulfonie group, reacted with bovine serum albumin, which car-ries positive charge through electrostatic force and hydrophobic interaction, to form a complex, resulting in a significant enhancement of resonance Rayleigh scattering (RRS) and the appearance of a new RRS spectrum with the maximum wavelength at 304 nm.At the same time, the second-order scattering (SOS) and frequency-doubling scattering (FDS) were enhanced obviously with a peak at 471 nm and 392 nm, re-spectively.The intensity of scattering (△I_(RRS), △I_(SOS) and △I_(FDS)) was directly proportional to the concentra-tion of CS in a certain range.When used in CS determination, this method exhibited high sensitivity, with a detection limit of 2.0(RRS), 2.9(SOS) and 13.2(FDS) ng/mL.The optimum conditions for the reac-tion and the influencing factors were investigated.The interference of foreign substances was examined and this method showed a good selectivity.The method can be applied satisfactorily to the determination of CS in eye drops.     

Dissolved Silica Adsorbed onto MnO_2 in Catalyzing the Decomposition of H_2O_2: Molecular Structural Rearrangement Revealed by FTIR,SEM-EDX and XRD

It has been generally unclear over the mechanism of inhibitory influence of silicate on structural rearrangement or solely physical adsorption onto manganese dioxide(MnO_2) about the decomposition of hydrogen peroxide(H_2O_2). Consequently,several experiments were carried out by using MnO_2 as a catalyst for the decomposition of H_2O_2 in a concentration series under certain concentrations of silicates. The silicates were analyzed by using a molybdenum blue colorimetric method. The results showed that the determination of silicates was inhibited by H_2O_2, whose inhibitory effect was greatly increased by increasing its concentration, but not limited by p H. SEM-EDX(scanning electron microscopy-energy dispersive x-ray spectrometry) results showed that the adsorption of silicates onto the surface of MnO_2 was not purely via a structural rearrangement, with increasing Mn atoms protruding on the outer surface by covering oxygen and silicon atoms. XRD(X-ray diffraction) and FTIR(Fourier transform infrared) spectra results further revealed no significant total crystal structural changes in MnO_2 after the adsorption of silicates, but only a small shift of 0.21° at 2θ from 56.36° to 56.15°, and a FTIR vibration showed at around 1 050 cm-1. The results, therefore, showed that silicate adsorption onto MnO_2 took place via both surface adsorption and structural rearrangement by interfacial reaction.     

Pretreatment of Rice Straw by Hydrogen Peroxide for Enhanced Methane Yield

A pretreatment process for hydrogen peroxide (H2O2) was optimized to enhance the biodegradation performance of rice straw and increase biogas yield. A determination experiment was conducted under predicted optimal conditions. Optimization was implemented using response surface methodology. The effects of biodegradation and the interactive effects of pretreatment time (PT), H2O2 concentration (HC), and substrate to inoculum ratio (S/I) on methane yield were investigated. The lignin, cellulose, and hemicellulose of rice straw were significantly degraded with increasing HC. The optimal conditions for the use of pretreated rice straw in anaerobic digestion were a 6.18-d PT, 2.68% HC (w/w total solid), and 1.08 S/I; these conditions result in a methane yield of 288 mL g-1 volatile solids (VS). A determination coefficient of 95.2% was obtained, indicating that the model used to predict the anabolic digestion process has a favorable fit with the experimental parameters. The determination experiment resulted in a methane yield of 290 mL g-1 VS, 88.0% higher than that of untreated rice straw. Thus, H2O2 pretreatment of rice straw can be used to improve methane yields during biogas production.     

钯(Ⅱ)-盐酸吗啉胍螯合物与卤代荧光素染料相互作用的超瑞利散射光谱及其分析应用研究

在pH=4.4～5.0的HAc-NaAc介质中,钯(Ⅱ)与盐酸吗啉胍(Abob)反应形成螯合阳离子,它能进一步与二溴荧光素(DBF)、曙红Y(EY),赤藓红(Ery)阴离子反应形成离子缔合物,引起超瑞利散射(HRS)显著增强.3个三元体系具有相似的光谱特征,最大HRS波长位于390 nm附近.在一定条件下超瑞利散射增强(△IHRS)与Abob的浓度成正比,其线性范围是0.029～3.0μg/mL(DBF),0.14～3.5μg/mL(EY)和0.23～1.9μg/mL(Ery),检出限分别为0.008 6μg/mL(DBF),0.043 μg/mL(EY)和0.069μg/mL(Ery).研究了HRS法的适宜反应条件和共存物质的影响,发展了高灵敏、简便快速测定Abob的新方法,可用于尿样中Abob的测定.

Abstract：

In an acidic medium with pH = 4.4-5.0, palladium (Ⅱ) chelated with moroxydine hydrochloride to form the cation [ Pd (Abob)]2+ , which reacted further with dibromofluorescein (DBF), eosin Y (EY)and erythrosin(Ery) to form ion-association complexes, respectively. As a result, the hyper Rayleigh scattering(HRS) intensities were enhanced greatly. The maximum HRS peak of the three systems was all located at approximately 390 nm. HRS intensity was proportional to the concentration of moroxydine hydrochloride (Abob) in the range of 0. 029-3.0 μg/mL for DBF, 0. 14-3.5 μg/mL for EY and 0.23-1.9 μg/mL for Ery, and their detection limit (3σ) was 0. 008 6, 0. 043 and 0. 069μg/mL, respectively. The optimum conditions of the reaction and the properties of analytical chemistry were investigated. Therefore, a new method for the determination of moroxydine hydrochloride(Abob) by HRS was developed. The method has high sensitivity and good selectivity and has been applied to the determination of Abob in uric samples with satisfactory results.     

Determination of Protein and Starch Content in Whole Maize Kernel by Near Infrared Reflectance Spectroscopy

Using 128 bulk-kernel samples of inbred lines and hybrids, a study was conducted to investigate the feasibility and method of measuring protein and starch contents in intact seeds of maize by near infrared reflectance spectroscopy (NIRS). The chemometric algorithms of partial least square (PLS) regression was used. The results indicated that the calibration models developed by the spectral data pretreatment of first derivative multivariate scattering correction within the spectral region of 10000 -4000 cm^-1, and first derivative straight line subtraction in 9000 - 4000 cm^-1 were the best for protein and starch, respectively. All these models yielded coefficients of determination of calibration (R^2cal) above 0.97, while R^2cv and R^2va1 of cross and external validation ranged from 0.92 to 0.95, respectively; however, the root of mean square errors of calibration, cross and external validation (RMSEE, RMSECV and RMSEP) were below l(ranged 0.3- 0.7),respectively. This study demonstrated that it is feasible to use NIRS as a rapid, accurate, and none-destructive technique to predict protein and starch contents of whole kernel in the maize quality improvement program.     

Expression,Purification and Structural Characterization of Mouse Talin-1 Head Δ139-168

Talin-1 head (hereinafter referred to as TH) is the head structure of talin protein,which contains a four-point-one-protein/ezrin/radixin/moesin (FERM) domain.Its F1 domain contains an unstructured loop of 30 amino acids (139-168),which does not interact with other domains.Because TH doesn't get the crystal structure and whether the unstructured loop has obvious influence on the TH secondary structure,therefore,the truncated talin-1 head Δ139-168 (hereinafter referred to as THΔ) was constructed and its structure and the impact of stability after truncation were analyzed.Molecular biology and structural biology methods were used to construct prokaryotic expression vectors of TH and THΔ,explore and optimize the expression conditions of recombinants,and they were purified by affinity chromatography and FPLC gel filtration chromatography.Finally,a large number of stable,high-purity protein samples were prepared successfully.The physicochemical properties and structural stability of the proteins were investigated by dynamic light scattering and circular dichroism.The results showed that the THΔ secondary structure of the truncated body did not change significantly,the structural stability was enhanced and the resistance to guanidine hydrochloride and high temperature was stronger.     

A new Curvularia lunata variety discovered in Huanghuaihai Region in China

The purpose of this study was to identify the dominant pathogens of Curvularia leaf spot and their pathogenicity variation in Huanghuaihai Region of China in recent years. In 2013 and 2016–2017, the occurrences of Curvularia leaf spots on maize were investigated in fields located in Henan, Hebei, Shandong, and Anhui provinces, and 292 fungi were isolated from diseased leaves. These fungal isolates were subjected to morphological identification, and 232 isolates were found to have about 70% uncurved conidia and were identified as Curvularia lunata var. Most of the conidia of 2 representative isolates, namely, HNWB-131 and HNWB-185, were oblong with parallel septations and were distinctly different from a reference isolate CX-3. For further determination, the internal transcribed spacer(ITS), glyceraldehyde 3-phosphate dehydrogenase(GPDH), the large subunit(LSU), and translation elongation factor 1-alpha(EF1-α) sequences of HNWB-131, HNWB-185, and CX-3 were amplified and sequenced. The results of sequence analysis showed that the 4 gene sequences from the 3 isolates had a similarity of more than 99% to C. lunata. Based on the sequences of ITS and the combined data of the 4 genes, neighbor-joining trees were constructed for phylogenetic analysis. The results indicated that these 3 isolates were clustered together with C. lunata. The expression of Clg2 p and ClUrase genes in mycelia and conidia was significantly(P0.05) higher in CX-3 than in HNWB-131 and HNWB-185. This study found that the dominant pathogen of Curvularia leaf spot was a new variety of C. lunata with morphological variations in Huanghuaihai Region from 2013 to 2017. The pathogenicity of the C. lunata var. was not significantly enhanced, and the expression of Clg2 p and ClUrase genes of C. lunata var. was decreased.