Independent development and validation of a novel six-color fluorescence multiplex panel including 61 diallelic DIPs and 2 miniSTRs for forensic degradation sample

Current forensic DNA profiles are obtained based on analyses of PCR product sizes or DNA sequence polymorphisms. Sometimes routine forensic analysis using short tandem repeat (STR) generates unsuccessful DNA testing result if the biological sample encountered is excessively degraded and low-template DNA. Herein, a new six-color fluorescence labeling system, including 59 autosomal diallelic deletion or insertion polymorphisms (DIPs), 2 miniSTRs, 2 Y-chromosome DIPs, and 1 Amelogenin gene with the amplicon sizes of less than 200 bp, was self-developed. According to the validation guidelines for DNA analysis methods formulated by the Scientific Working Group on DNA Analysis Methods, the validation studies have also been carried out for the multiplex system. This novel panel possessed the features of strong stability, high sensitivity, and good specificity, which was especially suitable for the forensic degraded and mixed sample detections. The cumulative power of exclusion and cumulative matching probability of the system were 0.9999978 and 9.833E-28, respectively, in Han Chinese in Hunan, China. Moreover, this system will be an effective new tool that can be independently applied to forensic personal identification and paternity testing in the populations from the East Asia region, even from the South Asia, America, and Europe regions. The system can also contribute to population phylogenetic affinity and genetic structure analyses among different populations.     

A guide for the meaningful surface analysis of wood by XPS and ToF-SIMS

The surface analysis of wood and wood products is becoming increasingly important for reasons ranging from the investigation of molecular constituents through to the optimization of industrial processes. As with any natural product, wood analysis is not straightforward, and this review aims to provide guidance for the successful surface analysis of wood by XPS and ToF-SIMS. Through example experiments, three themes are addressed relevant to obtaining meaningful results: considerations related to heterogeneity in the composition of wood (e.g., growth rings); the impact of the chemical removal of minor wood components known as extractives, and whether such a process is necessary; and the potential for misleading or erroneous results as a result of contamination occurring during sample preparation. In addition to discussing successful sample preparation approaches, the important role to be played by MVA in surface analysis is emphasized, particularly in the analysis of ToF-SIMS data. Examples of ToF-SIMS/MVA are provided that highlight the identification of contamination in sample preparation, the quantification of wood composition in terms of cellulose and lignin, and the indication of age of softwood samples. Through consideration of the complexities that influence wood surface analysis, the design and interpretation of consequential experiments become easier and more accurate.     

纳米表面相互作用及振动测头模型

如何实现高精度的测量是现代制造业及微电子技术领域的热点问题之一. 基于微纳米测头的三坐标测量机是当前实现高精度测量的重要手段. 随着测量尺寸的减小, 常用的纳米/微纳尺度的测头与待测表面之间形成静态接触, 其表面相互作用成为了影响其测量精度和可靠性的关键因素之一. 本文基于一种触发式振动测头, 研究了其动力学模型, 并通过对测头纳米尺度表面相互作用的理论分析及数值模拟, 确立了测头振动参数与表面相互作用之间的关联. 实验研究表明, 参数优化后的谐振微纳测头能有效抑制表面作用带来的干扰, 提高测量精度.     

Detection of NMR signals with a radio-frequency atomic magnetometer

We demonstrate detection of proton NMR signals with a radio-frequency (rf) atomic magnetometer tuned to the NMR frequency of 62 kHz. High-frequency operation of the atomic magnetometer makes it relatively insensitive to ambient magnetic field noise. We obtain magnetic field sensitivity of 7 fT/Hz1/2 using only a thin aluminum shield. We also derive an expression for the fundamental sensitivity limit of a surface inductive pick-up coil as a function of frequency and find that an atomic rf magnetometer is intrinsically more sensitive than a coil of comparable size for frequencies below about 50 MHz.     

用于食品安全分析样品前处理的共价有机聚合物的制备及应用进展

食品安全关系身体健康和生命安全,是全球关注的热点之一。食品基质复杂,痕量有毒有害物质分析之前必须经过有效的前处理。目前发展的前处理技术如固相萃取、磁固相萃取、固相微萃取等,其关键是吸附介质。共价有机聚合物是一类通过共价键连接而成的有机多孔材料,具有质轻、稳定性好、比表面积大、结构可控、易于修饰等特性,是一类优异的新型吸附材料。该文综述了近年来共价有机聚合物(COPs)在食品安全分析前处理中的应用进展。共价有机聚合物及其功能化复合材料通过简单的装填、聚合反应或化学键合固定到小柱或毛细管柱中用作固相萃取的吸附介质;通过一锅法、原位还原法、原位生长法或共沉淀法生成具有磁性的固相萃取吸附介质;或者通过物理涂覆、化学键合、溶胶凝胶法及原位生长法制备固相微萃取纤维。基于以上高吸附容量共价有机聚合物的样品前处理技术,食品中农残兽残、添加剂、环境污染物及生物毒素等得到了有效富集。最后,展望了COPs在食品分析样品前处理应用中的发展方向:简单高效绿色制备方法的开发,功能化COPs的设计合成;萃取机理的研究;高通量、高灵敏度分析方法研究。这些研究将促进COPs在样品前处理领域获得更广泛的应用。     

Three dimensional accurate morphology measurements of polystyrene standard particles on silicon substrate by electron tomography

Polystyrene latex (PSL) nanoparticle (NP) sample is one of the most widely used standard materials. It is used for calibration of particle counters and particle size measurement tools. It has been reported that the measured NP sizes by various methods, such as Differential Mobility Analysis, dynamic light scattering (DLS), optical microscopy (OM), scanning electron microscopy (SEM) and atomic force microscopy (AFM), differ from each other. Deformation of PSL NPs on mica substrate has been reported in AFM measurements: the lateral width of PSL NPs is smaller than their vertical height. To provide a reliable calibration standard, the deformation must be measured by a method that can reliably visualize the entire three dimensional (3D) shape of the PSL NPs. Here we present a method for detailed measurement of PSL NP 3D shape by means of electron tomography in a transmission electron microscope. The observed shape of the PSL NPs with 100 nm and 50 nm diameter were not spherical, but squished in direction perpendicular to the support substrate by about 7.4% and 12.1%, respectively. The high difference in surface energy of the PSL NPs and that of substrate together with their low Young modulus appear to explain the squishing of the NPs without presence of water film.     

Quantification of imatinib and related compounds using capillary electrophoresis-tandem mass spectrometry with field-amplified sample stacking

A quantification method for imatinib (IM), its major metabolite N-desmethyl imatinib (NDI), and a degradation by-product was developed using CE–MS combined with an online concentration technique. The use of multiple reaction monitoring (MRM)–MS/MS further improved the sensitivity of this technology. Liquid–liquid extraction (LLE) using tertiary butyl methyl ether yielded high recovery and reproducibility for the pretreatment of serum samples. The recovery rate exceeded 83% for all three analytes, and was 90% for IM. To improve quantification results, a conductivity-induced online analyte concentration technique, field-amplified sample stacking (FASS), was used. The S/N ratios were improved at least 10-fold when compared with conventional capillary zone electrophoresis. The detection limits were 0.2 ng/mL for IM, 0.4 ng/mL for NDI, and 4 ng/mL for the degradation by-product. These results are superior to those previously obtained by other reported methods. The new method was validated in terms of its selectivity, intra- and interday repeatability and accuracy, and sample storage stability, following the guidelines issued by the European Medicines Agency. Considering the convenient pretreatment procedure (LLE), superior sensitivity, and fast analysis speed (<15 min), this method can be useful in the determination of imatinib levels in blood.     

Derivatization-free determination of aminoglycosides by CZE–UV in pharmaceutical formulations

Aminoglycosides are a relevant class of antibiotics widely used by medics and veterinaries. There are a variety of reasons that make their determination relevant, such as quality control, environment and food contamination assessment, drug-release studies, among others. The lack of a chromophore makes aminoglycoside spectrophotometric detection particularly challenging, often requiring derivatization. In this work, an indirect detection method, making use of imidazole as a probe, applying CZE was successfully tested. It did not require derivatization, which simplified the sample preparation. Suitable figures of merit were obtained; recoveries between 95 and 105%, adequate repeatability and precision, correlation coefficients (r) above 0.998, and limits of detection (LODs) of 3.2 and 11 mg/L for gentamicin and paromomycin, respectively. As a proof-of-concept, it was also applied in a simple controlled release experiment that was well fitted using the Hill equation.     

石墨相氮化碳材料在样品前处理中的研究进展

作为一种新型非金属材料,石墨相氮化碳以其独特的优点,如简单的制备方法、优良的化学及热稳定性、良好的生物兼容性和无毒性等,受到越来越多的关注。石墨相氮化碳及其复合材料目前已被广泛应用于电催化、光催化、生物成像等领域。由于具有大的比表面积,同时又是富电子的疏水材料,石墨相氮化碳相关材料被认为是一种理想的样品前处理吸附剂。该文探讨了近年来石墨相氮化碳及其复合材料作为固相萃取、分散固相萃取、磁性固相萃取、固相微萃取吸附剂在样品前处理中的应用,并对未来的发展趋势和应用前景进行了展望,以期为相关领域的研究提供帮助。     

典型全氟有机酸类化合物的样品前处理与分析方法研究进展

全氟辛烷磺酸（PFOS）和全氟辛烷羧酸（PFOA）是两种典型的全氟有机酸类化合物,也是全氟化合物（PFCs）前体物的最终降解产物,具有肝毒性、胚胎毒性、生殖毒性、神经毒性,检出率最高。在各种被污染的介质中,PFOS和PFOA含量往往很低,基体复杂多样,快速高效的样品前处理技术成为测定的关键环节。目前,国际上对PFOS和PFOA的测定无统一标准,而我国关于PFCs的分析研究落后于国际发展水平。该文介绍了PFOS和PFOA的特性,系统总结和评述了前处理技术（液液萃取、固相萃取、固相微萃取、超声萃取和QuEChERS法）及分析方法（色谱-质谱方法、光谱法、酶联免疫法和电化学法）,以期为PFOS和PFOA的分析监测及标准制定提供参考。