Differential pre‐amplification of STR loci for fragmented forensic DNA profiling

DNA profiling of short tandem repeats (STR) has been successfully used for the identification of individuals in forensic samples, accidents and natural disasters. However, STR profiling of DNA isolated from old crime scenes and damaged biological samples is difficult due to DNA degradation and fragmentation. Here, we show that pre‐amplification of STR loci using biotinylated primers for the STR loci is an efficient strategy to obtain STR profiling results from fragmented forensic samples. Analysis of STR loci with longer amplicon sizes is generally hampered, since these relatively long loci are vulnerable to DNA fragmentation. This problem was overcome by using reduced or increased primer concentrations for loci with shorter or longer amplicon sizes, respectively, in our pre‐amplification strategy. In addition, pre‐amplification of STR loci into two groups of short or long amplicon size increases the efficiency of STR profiling from highly fragmented forensic DNA samples. Therefore, differential pre‐amplification of STR loci is an effective way to obtain DNA profiling results from fragmented forensic samples.     

球形阳离子凝胶的制备及吸附性能研究

以醛、酮、胺为原料,采用溶液缩聚和反相悬浮聚合制备了新型高吸附容量球形阳离子凝胶,对产物的分子结构和表面形貌进行了表征。通过吸附实验,研究了其对阴离子染料氨基黑10B和表面活性剂十二烷基苯磺酸钠(SDBS)的吸附效果,并讨论了吸附行为和机理。实验结果表明,球形阳离子凝胶具有较高的阳离子度和大量极性官能团,其对氨基黑和SDBS的吸附是基于静电引力和氢键等分子间力共同作用的结果,凝胶吸附效果随溶液pH的降低而升高。吸附质分子随溶液渗透进入球形凝胶并被吸附于凝胶内表面,故该吸附主要由吸附质在凝胶内部的扩散过程控制,具有较高的饱和吸附量。     

Metal dicarbides as intermediate species in thermal ion formation mechanisms

Lanthanide elements (lanthanum to lutetium) and actinide elements (uranium and plutonium) adsorbed onto resin beads and mounted on rhenium filaments were studied as thermal ionization sources. Temperatures at which these ion sources gave maximum intensities were measured for each of these elements. The temperature trends correlate with the dissociation energies of the corresponding metal dicarbide compounds. The metal dicarbide functions as a carrier to take the lanthanide and actinide elements to higher temperatures than would be attainable otherwise. This results in release of the atomic species at a higher temperature where ionization probability is significantly increased.     

亲和吸附剂对细菌内毒素吸附性能的研究

制备了以球形纤维素为载体、8种氨基酸和1种聚赖氨酸为配基的吸附剂,对质量浓度为100.0pg/mL的内毒素水溶液进行了吸附研究,绘制了吸附等温线,并初步探讨了吸附机理.结果表明,精氨酸和赖氨酸配基具有良好的吸附能力,在1.5mL100.0pg/mL内毒素溶液中吸附量分别达到182.0和160.0pg/mL;吸附等温线显示,以赖氨酸为配基的吸附剂其吸附量随溶液内毒素浓度增加而线性增加,符合Langmuir吸附方程,吸附能力强,具有一定的临床应用前景.     

Apparent relaxation‐time spectrum cutoff in dilute polymer solutions: An effect of solvent dynamics

The apparent short time cutoff of the relaxation‐time spectrum at surprisingly long times for polymers in solution is a well known but not yet understood observation. To elucidate its origins we revisit viscoelastic and oscillatory flow birefringence data for solutions and melts of two linear polymers (polystyrene and polyisoprene) and present new measurements of oscillatory flow birefringence of the latter. Previous measurements have suggested that the “flexibility” of both polymers in solution is smaller than in the melt on the basis of the breadth of the relaxation‐time spectrum of the solution as compared with that of the melt. Our new measurements have explored a higher effective frequency range than was previously possible. This has allowed us to observe the effect of the rotational relaxation time of the solvent on the dynamics of the solution at high frequencies. To obtain the polymer global motion contribution, one now needs to subtract from the solution properties a frequency‐dependent complex solvating environment contribution. We show that the decrease in apparent “flexibility” for solutions arises from the presence of a solvent that exhibits a rotational relaxation time and thus simple viscoelastic behavior somewhat near the frequency window of the experiment. Although recent predictions of a model for a chain in a solvent with a single relaxation time are in qualitative agreement with our results, our data suggest that the solution results may reflect the influence of solvent on the development of the “entropic spring” forces at short times. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2860–2873, 2001     

基于磁性微球的无标记化学发光端粒传感新技术

近年来无标记型DNA传感技术的研究已成为病原基因测定和基因疾病诊断等领域新的研究热点之一. 基于磁性微球分离和富集的方法, 建立了一种新型的无标记化学发光检测技术, 并成功地应用于特定序列DNA——端粒的检测. 首先采用dT₂₀修饰的磁性微球, 与连接有dA₂₀的捕获探针DNA杂交, 然后再与端粒进行第二步杂交反应. 磁性分离洗涤后, 利用端粒中富含的G碱基与3,4,5-三甲氧基苯乙二醛反应产生特异性化学发光, 从而实现特定序列 DNA——端粒的无标记检测. 实验结果表明: 该法具有操作简便、分析快速、灵敏度高、专属性好等特点. 目标DNA浓度在5×10^－9～1×10^－7 mol/L浓度范围内具有良好的线性关系, 相关系数为0.9918.     

Analysis of Resin-Bead Loaded U And PU Samples with a Single-Stage Mass Spectrometer

Abstract

The resin bead sample loading technique has been applied to a conventional single-stage mass spectrometer equipped with pulse counting. Isotopic data obtained for U and Pu are comparable to those obtainable from similar instruments using conventional techniques.     

Detection and Spectrophotometric Determination of Uranyl Ion with Erichromcyanine R

Abstract

Colour reaction has been studied for the identification and the spectrophotometric determination of uranyl ion with Erichromcyanine R. The detection limit was 7 μg. Beers law is obeyed in the concentration range containing 13 μg to 125 μg/10 ml of uranium.     

Simultaneous Plutonium and Uranium Isotopic Analysis from a Single Resin Bead - A Simplified Chemical Technique for Assaying Spent Reactor Fuels

Abstract

The method uses basic anion resin to adsorb plutonium and uranium from 7–8 M HNO₃ solutions containing dissolved spent reactor fuels. After equilibrating the resin with the solution, a single bead is used to determine the isotopic composition of plutonium and uranium on sample sizes as small as 10^?9 to 10^?10 g of each element per bead. Isotopic measurements are essentially free of isobaric interferences and fission product contamination in the mass spectrometer is eliminated. A very small aliquot of dissolver solution containing 10^?6 g of U and 10^?8 g of Pu is sufficient sample for chemically preparing several resin beads. A single prepared bead is loaded onto a rhenium filament and analyzed in a two-stage mass spectrometer using pulse counting for ion detection to obtain the high sensitivity required. Total quantity of the elements, in addition to isotopic abundances, can be determined by isotope dilution. Other areas where the method may be useful are: in plutonium production, isotope separations, and for trace detection of contamination on reactor parts.     

微玻璃球回归反光条件的理论分析

对回归反光膜中微玻璃球的反光机制进行了研究，建立了微玻璃球对平行光束的回归散射模型并进行了理论计算，确定了微玻璃球回归反光的最佳条件。