Expansion of a SNaPshot assay to a 55‐SNP multiplex: Assay enhancements,validation, and power in forensic science

A previously developed multiplex assay with 44 individual identification SNPs was expanded to a 55plex assay. Fifty‐four highly informative SNPs and an amelogenin sex marker were amplified in one PCR reaction and then detected with two SNaPshot reactions using CE. PCR primers for four loci, 28 single‐base extension primers, and the reaction conditions were altered to improve the robustness of the method. A detailed approach for allele calling was developed to guide analysis of the electropherogram. One hundred and eighty unrelated individuals and 100 father‐child‐mother trios of the Han population in Hebei, China were analyzed. No mutation was found in the SNP loci. The combined mean match probability and cumulative probability of exclusion were 1.327 × 10^?22 and 0.999932, respectively. Analysis of the 54 SNPs and 26 STRs (included in the AmpFLSTR Identifiler and Investigator HDplex kits) showed no significant linkage disequilibriums. Our research shows that the expanded SNP multiplex assay is an easily performed and valuable method to supplement STR analysis.     

A sensitive and semi-quantitative method for determination of multi-drug residues in animal body fluids using multiplex dipstick immunoassay

The objective of this research was to develop a multiplex dipstick immunoassay method for the simultaneous determination of multi-veterinary drug residues, such as β-agonists, sulfonamides, and tetracyclines in milk, urine, and serum. The multiplex dipstick assay format was based on an indirect competitive approach: Three test lines (different antigens) and one control line (goat anti-mouse IgG) were located on the strip membrane. Labeled antibodies were freeze-dried in microwells. Samples did not require pretreatment and could be directly analyzed within 10 min. Threshold levels in different sample matrices were visually estimated at 0.3–0.45 ng mL⁻¹ for clenbuterol; 3–4 ng mL⁻¹ for sulfadiazine; and 4.5–6 ng mL⁻¹ for tetracycline, respectively. The linear relationship between the concentrations of veterinary drug residues and the Au nanoparticles plasmon absorbance allowed quantitative determination of these veterinary drug residues. The recoveries of clenbuterol, sulfadiazine and tetracycline in spiked samples ranged from 78.4% to 112.6%, and the relative standard deviations were below 11.2%. Analysis of animal samples suggested that the proposed multiplex dipstick assay method was consistent with the LC-MS/MS method. The percentage of false results was less than or equal to 5%. Thus, the proposed multiplex dipstick assay is inexpensive, easy-to-use, and suitable for the purposes of rapid and comprehensive screening of 3 families of β-agonists, sulfonamides and tetracyclines including 26 drugs in animal body fluids.     

Development and validation of a forensic six-dye multiplex assay with 29 STR loci

This paper describes the development and validation of a novel 31-locus, six-dye STR multiplex system, which is designed to meet the needs of the rapidly growing Chinese forensic database. This new assay combines 20 extended-CODIS core loci (D3S1358, D5S818, TPOX, CSF1PO, TH01, vWA, D7S820, D21S11, D8S1179, D18S51, D16S539, D13S317, FGA, D1S1656, D2S441, D2S1338, D10S1248, D12S391, D19S433, and D22S1045), nine highly polymorphic loci in Chinese Han population (D3S3045, D6S1043, D6S477, D8S1132, D10S1435, D15S659, D19S253, Penta D, and Penta E), and two gender determining markers, amelogenin and Y-Indel, which could amplify DNA from extracts, as well as direct amplification from substrates. To demonstrate the suitability for forensic applications, this system was validated by precision and accuracy evaluation, concordance tests, case sample tests, sensitivity, species specificity, stability, stutter calculation, and DNA mixtures, according to the guidelines described by the Scientific Working Group on DNA Analysis Methods (SWGDAM) and regulations published by the China Ministry of Public Security. The validation results indicate the robustness and reliability of this new system, and it could be a potentially helpful tool for human identification and paternity testing in the Chinese population, as well as facilitating global forensic DNA data sharing.     

表面等离激元金属纳米粒子的多元化结构及应用

目前, 单一的金属纳米粒子结构已经难以满足多学科交叉发展的需求. 因此, 将多种金属纳米粒子(如不同尺寸、 形状、 组分等)集成在同一基底表面, 能够充分发挥不同金属纳米粒子的性质和优势, 极具研究价值和应用价值. 本文介绍了多元化表面等离激元纳米粒子结构的构筑方法, 以及其在信息编码、 光电器件、 能源催化等领域的应用. 最后, 提出了当前在多元化结构制备中存在的挑战, 并展望了利用多元化结构实现性能提升的前景.     

多指标免疫分析的研究进展

免疫分析是临床上检测生理相关蛋白质指标的主要方法. 与单一指标的免疫分析相比, 临床体外诊断对多指标的生理相关蛋白质免疫分析有着更为广泛的需求. 通过在固相载体上完成免疫反应的非均相免疫分析具有灵敏度高的优点, 是当前多指标免疫分析的主流方法. 本文按照固相载体的不同, 对近年来的多指标免疫分析系统分别从技术原理、 实现方法、 各自特点等方面的研究进展进行综合阐述. 最后对比总结了不同系统的优势与不足, 并展望了微流控多指标免疫分析在即时检测领域的发展前景.     

Modeling the COVID-19 epidemic and awareness diffusion on multiplex networks

The coronavirus disease 2019(COVID-19)has been widely spread around the world,and the control and behavior dynamics are still one of the important research directions in the world.Based on the characteristics of COVID-19’s spread,a coupled disease-awareness model on multiplex networks is proposed in this paper to study and simulate the interaction between the spreading behavior of COVID-19 and related information.In the layer of epidemic spreading,the nodes can be divided into five categories,where the topology of the network represents the physical contact relationship of the population.The topological structure of the upper network shows the information interaction among the nodes,which can be divided into aware and unaware states.Awareness will make people play a positive role in preventing the epidemic diffusion,influencing the spread of the disease.Based on the above model,we have established the state transition equation,through the microscopic Markov chain approach(MMCA),and proposed the propagation threshold calculation method under the epidemic model.Furthermore,MMCA iteration and the Monte Carlo method are simulated on the static network and dynamic network,respectively.The current results will be beneficial to the study of COVID-19,and propose a more rational and effective model for future research on epidemics.     

Rapid identification of diarrheagenic Escherichia coli based on barcoded magnetic bead hybridization

Diarrhea, as a global public health problem, causes a large number of infections and deaths every year. Although Escherichia coli (E. coli) is one of the normal flora microorganisms in the human intestinal tract, it has five pathogenic bacteria types that can cause human diarrhea, known as diarrheagenic E. coli. When people are infected, rapid and accurate diagnosis, along with timely treatment, are especially important. Here, we introduce a new method to identify and analyze a large number of pathogenic strains in E. coli by multiplex PCR and barcoded magnetic bead hybridization. Results show that the detection sensitivities of enterohemorrhagic E. coli, enterotoxigenic E. coli, enteropathogenic E. coli, enteroinvasive E. coli and enteroaggregative E. coli were 1.3 × 10³ CFU/mL, 2 × 10⁴ CFU/mL, 4 × 10⁴ CFU/mL, 7.2 × 10⁴ CFU/mL and 1.7 CFU/mL respectively. This method has strong specificity and high sensitivity and detects multiple target sequences in one experiment. Compared with other methods, BMB array has great application potential.     

Development of multiplex PCR system with 15 X-STR loci and genetic analysis in three nationality populations from China

The aim of this study is to develop a new multiplex PCR system that simultaneously amplifies the 15 X-chromosome short tandem repeats (X-STRs) loci in the same PCR reaction, and to obtain the 15 X-STR loci database in three nationality populations from China. This multiplex system includes DXS7133, DXS6801, DXS981, DXS6809, DXS7424, DXS6789, DXS9898, DXS7132, GATA165B12, DXS101, DXS10075, DXS6800, GATA31E08, DXS10074, and DXS10079, which were successfully analyzed on 1251 DNA samples (670 males and 581 females) from Guangdong Han population, Xinjiang Uigur and Kazakh. The allele frequencies and mutation rates of the 15 loci were investigated, and the allele frequency distribution among different populations was compared. A total of 6-17 alleles for each locus were observed and altogether 170 alleles for all the selected loci were found. Thirteen cases with mutation of the above loci were detected in 11,850 meioses. Pairwise comparisons of the allele frequencies distribution showed significant differences in most loci among different populations. The results indicate that this multiplex system may provide high polymorphism information for kinship testing and relationship investigations, and it is necessary to gain allele frequency and mutation rate of different population for forensic application.     

高压变频器多重化整流的设计

高压变频器是指输入电源电压在3kV—10kV的大功率变频器。由于其功率大、电压等级高,应用场合重要。所以对其输入谐波、功率因数等要求很高。因此采用移相变压器实现高压变频器的多重化整流,可使高压变频器的输入谐波减小,功率因数提高。