Quantum dots (QDs) exhibit excellent optical and chemical properties, making them advantageous for fluorescence sensing. However, gas sensor using QDs is often hampered by challenges such as gas diffusion and low concentration. This work describes the development of a nitrogen dioxide (NO2) fluorescence gas sensor that utilizes a QDs@Aerogels/SM composite nanofilm containing CdTe QDs modified by reduced glutathione (GSH), silica microspheres (SMs), and silica aerogel. The SM and porous aerogels create a uniform porous structure that enhances the distribution of QDs. Compared to the pure QDs film, the QDs@Aerogels/SM composite film exhibits enhanced fluorescence intensity. The porous structure promotes the adsorption of NO2, which improves the detection sensitivity. The QDs@Aerogels/SM composite film was applied in a portable gas sensor. The sensor demonstrates a good linear response to NO2 gas in the range of 0-10 ppm, with an ultra-low detection limit of 0.096 ppm and high selectivity. The uniform distribution of aerogel and SM enhances the stability of the composite nanofilm, and the fluorescence of the films remains virtually unchanged over a period of 60 days which ensures its optimal performance over extended periods of use. The fluorescent NO2 sensor demonstrated selective and sensitive quenching upon exposure to NO2, making it ideal for environmental monitoring and further applications. (c) 2024 Optica Publishing Group. All rights, including for text and data mining (TDM), Artificial Intelligence (AI) training, and similar technologies, are reserved.

As a highly functional platform, lab-on-fiber (LOF) has exhibited amazing potential to be used in ultrasensitive surface-enhanced Raman spectroscopy (SERS) detection. However, the low detection efficiency and high cost of most SERS-based LOF platform have severely limited their further applications in environmental monitoring, biomedicine, etc. Here, we report a reusable SERS-based LOF platform through a Au-coated optical fiber integrated into a patterned microfluidic chip. With the assistance of laser-induced thermophoresis, we successfully obtained rich "hot spots" on the Au-coated optical fiber by reversible accumulation of gold nanoparticles within 5 min. Experimental results indicate that it has a low detection limitation of 10(-10) mol/L (M) for environmental pollutant molecules. Fortunately, with the dynamic and reversible accumulation of gold nanoparticles controlled by laser on/off, the platform shows excellent reversibility and stability under multiple detection-cleaning cycles, which are better than those of the LOF platform based on chemical modification and photochemical deposition. The thermophoresis-based LOF platform with the advantages of easy operation, miniaturization, and high reusability provides a cost-effective approach for SERS detection.

Fluorescent sensors are resistant to electromagnetic interference and are electrically insulated, allowing for highly accurate measurements. Quantum dots (QDs) serve as outstanding sensing materials owing to the unique optical properties such as tunable photoluminescence (PL), excellent visible light activity, and high chemical and physical stability. In this paper, we develop an optical humidity sensor based on a QDs nanocomposite film. The film is made of polyvinyl alcohol (PVA), SiO2 microsphere (SM), and QDs through the layer-by-layer self-assembly method. The mechanism of humidity detection is moisture-induced quenching of the QDs fluorescence intensity. The results reveal that our sensor shows a good linear response to relative humidity in the range of 5% to 97%, a fast response-recovery time of 25 s and 20 s, and good repeatability for more than 50 cycles as well as high stability for over 180 days. Possessing the remarkable property, optical humidity sensors are envisaged for great potential applications in environmental monitoring.

介绍氦中甲烷气体标准物质的制备方法.以超纯氦气和高纯甲烷为原料,采用称量法制备特性值为10μmol/mol的氦中甲烷气体标准物质.采用气相色谱法(DID检测器)对制备的标准物质进行均匀性、稳定性检验,并对定值结果的不确定度进行评定.研制的气体标准物质均匀性和稳定性良好,有效期为12个月,相对扩展不确定度为2％(k=2).该气体标准物质可用于氦离子化气相色谱仪的方法评价和校准.

介绍异辛烷中六氯苯溶液标准物质研制方法.以色谱纯异辛烷和已准确定值的六氯苯为原料,采用重量–容量法准确制备特性量值为10.0 ng/μL的异辛烷中六氯苯溶液标准物质.分别采用F检验和t检验对标准物质进行均匀性、稳定性检验,并对定值结果的不确定度进行评定.结果表明该标准物质均匀性和稳定性良好,有效期为12个月,定值结果的相对扩展不确定度为3％(k=2),已被批准为国家二级标准物质,编号为GBW(E)082880.该标准物质可用于环境污染物六氯苯的定性及定量分析和气相色谱–质谱联用仪的校准.

研制氢中氦气体标准物质,以高纯氦和高纯氢为原料,采用称量法制备氢中氦气体标准物质.气相色谱(TCD)分析法对制备的标准气体进行性能评价.研制浓度为300μmol·mol-1的氢中氦气体标准物质,相对扩展不确定度为2％(k=2).该气体标准物质具有良好的均匀性和稳定性,可用于氢燃料电池汽车用氢气分析方法的确认和评价.

研制基于聚乙烯醇(PVA)固定直径为5μm的二氧化硅小球制成的模板阵列和基团修饰量子点的甲醛气体传感器.通过模板法,利用量子点和20 nm表面修饰羟基二氧化硅的三维沉积制备敏感材料,并负载于PVA和二氧化硅微球的薄膜上,制备复合敏感膜.对比油胺、羧基、氨基修饰的量子点对甲醛的响应,表面修饰氨基的量子点对甲醛十分敏感,在120 s内其荧光强度从45000猝灭至40000.通过改进量子点成膜工艺实现对甲醛气体的特异性检测,开发新型微纳光学传感器件用于超低浓度气体的快速实时监测.以0～2μL/L低浓度甲醛气体的检测为例,利用荧光量子点的量子尺寸效应和表面修饰特性,实现甲醛气体的微量、高灵敏度、快速响应的实时监测.该仪器具有抗电磁干扰强、响应速度快、操作简单、制作成本低廉等优势,为基于荧光增强的量子点光学传感器在气体检测等方面的研究提供了新的制备思路和研究方向.

The synergistic integration of optofluidic and surface enhanced Raman scattering (SERS) sensing is a new analytical technique that provides a number of unique characteristics for enhancing the sensing performance and simplifying the design of microsystems. Here, we propose a reusable optofluidic SERS sensor by integrating Au nanoisland substrate (AuNIS)-coated fiber into a microfluidic chip. Through both systematic experimental and theoretical analysis, the sensor enables efficient self-cleaning based on its optical-to-heat-hydrodynamic energy conversion property. Besides, the sensor exhibits the instrument detection limit down to 10-13mol/L and enhancement factor of 106 for Rhodamine 6G. Our optofluidic SERS sensor with such a photothermal microfluidic-assisted self-cleaning method has the advantages of portability, simple operation, and high cleaning efficiency, which will provide a new, to the best of our knowledge, concept and approach for cost-effective and reusable sensors.

以色谱纯甲醇和高纯物质萘为原料,采用重量-容量法准确制备特性量值为1.00×10-4 g/mL的甲醇中萘溶液标准物质.研制的标准物质通过了均匀性检验和稳定性考察,并对定值结果进行了不确定度评定.该溶液标准物质已被批准为国家二级标准物质(编号GBW(E)130395),相对扩展不确定度为3％(k=2),可用于液相色谱仪的检定.

为实现气相色谱仪温度参数的自动化检定,设计了一套新型的温度自动检定系统.给出了温度数据采集仪的组成和模块设计,采用Android Studio开发环境,串口通信技术,完成了Java编程的Android手机端应用软件,实现了温度的测量和气相色谱仪的柱箱温度稳定性、程序升温重复性的自动检定.最后对温度数据采集仪准确性进行验证,在测量范围内示值误差均小于0.30℃,证明了该设计的可行性.与传统的检定方法相比,本文设计的气相色谱仪温度自动检定系统提高了工作效率,为检定人员减负减压.

以高纯硫化氢和高纯甲烷为原料,采用称重法制备甲烷中硫化氢气体标准物质.采用气相色谱法(FPD)进行均匀性、稳定性考察.结果表明用称量法制备的浓度为10μmol/mol的甲烷中硫化氢气体标准物质均匀性良好,稳定性可靠,符合气体标准物质制备的要求.该气体标准物质相对扩展不确定度Urel=2％,k=2.

A highly efficient gas sensor was developed based on photocatalysis heteronanostructures comprised of Au adsorbed on CdTe quantum-dot film (CdTe@Au) with alkalization treatment. The plasmonic-enhanced surface reactions lead to a valuable application for gas sensing.

Entomopathogenic Photorhabdus bacteria produce two types of intracellular crystalline inclusion proteins,CipA and CipB,as the nutrient resource for the symbiotic nematode.Based on constructed high-level prokaryotic expression system,recombinant Cip proteins were purified with a warm extract method and used as the antigens to immune New Zealand rabbits,respectively.The polyclonal antibodies with the titers of 1∶6 400 were raised and monitored by indirect enzyme-linked immunosorbent assay(ELISA).Western blot assay confirmed that the antibodies could specifically recognize the inclusion proteins in Photorhabdus bacteria.Preparation of Cip polyclonal antibodies will be helpful to develop the immunological assay method of these proteins.

[Objective] Phase I cells of Photorhabdus luminescens bacteria,symbiotically associated with entomopathogenic Heterorhabditis nematode,produce two types of intracellular crystalline inclusions,CipA and CipB,to support the symbiont.This study aimed to investigate the possible influence of Cip proteins on non-symbiotic Steinernema nematode.[Methods] Based on constructed Escherichia coli expression system of Cip proteins,co-culture system of recombinant E.coli bacteria and Steinernema sp.SY-5 nematode was set up.[Results] The Cip proteins significantly promoted the development of SY-5 nematode to make high adult rate of 65%-82%,gravid rate of 80%-95%,30-50 eggs per nematode,and low mortalities.[Conclusion] As the nutrient reserves for Heterorhabditis nematode,Cip proteins can be accepted and utilized by Steinernema nematode.The progress on these proteins will provide insights into the mechanisms governing bacteria-nematode symbiosis.

Full-automatic biochemical analyzer is one of important means for clinical diagnostic. But its calibrating work is very difficult, and the exercisable calibration technique of this instrument is rarely seen. This test mainly discusses a kind of calibration technique for fall-automatic biochemical analyzer.

本文介绍了影响能量色散X射线荧光光谱仪测量准确性的因素及如何进行谱图分析,减少测量误差,提高测量数据的准确性.