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1.
分析方法标准验证实验得到的分析方法基本性能参数重复性限和再现性限是日常检测工作质控规范重要依据。以环境监测领域土壤、沉积物及固废样品中无机元素分析为例,考察了已颁布执行的标准文本和在生态环境部官网公开征求意见的分析方法标准中重复性限。将重复性限转化为相对偏差后,与日常检测工作中质控限值进行了比较。根据目前现行有效的平行双样测定结果相对偏差限值,方法验证数据有多大比例符合质控要求?根据方法验证结果,平行双样测定结果相对偏差限值有无改进可能?从上述两个角度进行了研究。研究结果表明:土壤、沉积物、固体废弃物中无机元素的测定,不同文献来源相同分析方法标准和不同分析方法标准,其重复性限转化得到的平行测定相对偏差合格率存在明显区别;用平行测定相对偏差限值可以快速判断标准文本中的重复性限是否合理,审核方法验证数据质量是否满足要求。基于已有标准文本方法验证数据,探讨了修改平行测定结果相对偏差限值可行性。  相似文献   
2.
重金属污染一直影响着人们的健康生活,如镉,铅和铜等的污染,故而土壤重金属的快速检测和如何预防,一直受各国学者关注和研究。传统土壤重金属检测方法(如原子吸收光谱法、X荧光光谱法等)样品预处理复杂,分析成本较高,易形成样品的二次污染,不能满足快速分析的要求。激光诱导击穿光谱(LIBS)是一种典型的原子发射光谱,它是基于分析物质中原子和离子受激发而发射的特征谱线信息,进而研究物质成分的分析方法。LIBS技术能够快速检测任何状态(固、液和气态)物质元素的成分和含量,被看作是未来化学检测和快速绿色分析领域的新兴技术。LIBS技术具有对样本简单预处理(或不需要处理)、多元素同步分析、远距离测量、适用性广等优势,被广泛用于生活生产的各个领域,已成为近年来国内外学者广泛关注和研究的热点之一。在农业信息快速感知的大背景下,以激光诱导击穿光谱技术为技术手段,以土壤重金属铅元素为研究对象,运用理论分析和数学建模相结合,建立了多种基于单变量定标曲线的土壤重金属铅检测模型,并进行了模型验证。自制15个已知的铅元素浓度梯度的谱线土壤样本,在获取了土壤LIBS数据之后,对其进行预处理对比,建立了基于谱峰强度、谱峰积分、洛伦兹拟合强度三种定标曲线模型,对土壤中铅元素含量进行定量分析,得出基于三种定标曲线模型对土壤中铅元素含量的预测决定系数R2分别为0.918 0,0.910 1和0.914 3,三种定标曲线分析方法的预测结果都较好,说明了LIBS结合单变量定标曲线法对土壤中铅含量的检测可靠性高。最后选取部分样本数据进行验证,结果较好。研究结果为研发便携式农田土壤污染物检测技术与装备提供技术支撑,也为农田精准管理和科学施肥奠定基础。  相似文献   
3.
This paper provides a quantitative analysis of the resistance force of the locked-wheel for push-pull locomotion rovers using intentional sinkage. Our previous study has confirmed that push-pull locomotion using intentional subsidence at an initial position can contribute to improving the traveling performance. The key factor of this scheme is the resistance force of the locked-wheel. However, the resistance force at different sinkage conditions and wheel sizes (e.g., mass, width, and diameter) remains unclear, especially for the individual locked-wheel. The detailed investigation of this interaction can contribute to the accurate estimation of rover mobility. This paper, therefore, investigates the locked-wheel and soil interaction at different sinkage conditions experimentally, especially focusing on the intentional sinkage condition. Additionally, the resistance force is considered theoretically through the knowledge based on the soil flow patterns beneath the locked-wheel. The experimental results confirmed that the resistance force of the locked-wheel rose as the initial sinkage, wheel size, and weight increases. Furthermore, the theoretical calculation suggested the resistance force increased with a similar tendency of the experimental data.  相似文献   
4.
张华强  杨帅  杨洋  张蕾 《化学教育》2022,43(23):1-7
介绍了中国胭脂的演变简史,以化学视角对胭脂的发展进行分类:无机胭脂、有机胭脂(天然植物胭脂、有机合成类胭脂)等。进行模拟实验研究,探究胭脂制作工艺流程,分析胭脂中红色物质的成分和显色机制。阐述每个阶段胭脂的不足之处,科普胭脂中的红色化学知识,体会化学对美和健康的重要意义,感受化学的无穷魅力。  相似文献   
5.
It is highly desired yet challenged to find an adsorbent with low cost and excellent performance in the removal of organic dyes from aqueous solution. Here we reported that a layered cationic aluminum oxyhydroxide material hydrothermally synthesized from the low-cost source materials of AlCl3∙6H2O, CaO and H2O, known as JU-111, can meet such criterion in removing methyl orange(MO) and Congo red(CR). JU-111 shows fast adsorption kinetics[especially for CR(15 s)] and high adsorption capacity(MO:>1000 mg/g; CR:>2900 mg/g), surpassing most of the reported adsorbents. Comprehensive characterizations of the adsorption process of MO and CR revealed that both adsorptions were achieved via the anion exchange process. The characteristics of extremely low cost and excellent performance render JU-111 great potential in the practical applications in the removal of anionic dyes.  相似文献   
6.
采用简单的水热法合成了六角柱形NaErF_(4)和NaErF_(4)@NaYF_(4)核壳上转换发光材料,利用扫描电镜(SEM)、X射线粉末衍射(XRD)和荧光光谱(PL)等表征对材料的形貌、结构和上转换发光性能进行了研究。结果表明,纯NaErF_(4)样品为六角柱形,边长和厚度均为1μm左右,样品表面光滑。随着NaYF_(4)壳层的包覆,六角相NaErF_(4)周围出现了大量的立方相NaYF_(4)纳米颗粒,得到了NaErF_(4)@NaYF_(4)核壳结构。荧光光谱表明,通过在六角柱形NaErF_(4)表面包覆NaYF_(4)壳层,可以有效增强上转换发光强度,其中,位于527,543,663 nm处的3个发射峰分别对应于Er^(3+)的^(2)H_(11/2)→^(4)I_(15/2)、^(4)S_(3/2)→^(4)I_(15/2)和^(4)F_(9/2)→^(4)I1_(5/2)能级跃迁。随着壳层中Y∶F比例的增加,立方相NaYF_(4)的晶体衍射峰逐渐增强;同时,对应的NaErF_(4)@NaYF_(4)样品发射光谱中红绿比(R/G)逐渐增大,发光颜色也从绿色、经黄绿色逐渐向黄色过渡,实现了多色发光。  相似文献   
7.
Using aqueous extraction of red sanders powder as a reducing agent, silver and copper bimetallic nanoparticles were in situ generated in cotton fabrics. Silver and copper nanoparticles were also generated separately for comparison. The resulted nanocomposite cotton fabrics (NCFs) were characterized by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and antibacterial tests. SEM analysis indicated the generation of more number of nanoparticles when bimetallic source solutions were used. Further, the size range of the generated bimetallic nanoparticles was found to be lower than when individual metal nanoparticles were generated in NCFs. XRD analysis confirmed the in situ generation of silver and copper nanoparticles when equimolar bimetallic salt source solutions were utilized. The NCFs with bimetallic nanoparticles exhibited higher antibacterial activity against both Gram-negative and Gram-positive bacteria and hence can be considered for applications as antibacterial bed and dressing materials.  相似文献   
8.
Endophytic fungi were isolated from red alga Asparagopsis taxiformis - Falkenbergia stage, collected from the Brazilian coast, and were identified as Annulohypoxylon stygium (AT-03) and A. yungensis (AT-06) based on their macro/micromorphological and molecular features. Bioassay-guided fractionation of the EtOAc extract from laboratory cultures of both strains yielded known compounds pyrogallol from A. stygium, (3R)-scytalone and (3R,4R)-4-hydroxy-scytalone from A. yungensis. Pyrogallol was active against methicillin-resistant Staphylococcus aureus (MRSA) and Escherichia coli strains. An inactive fraction from A. stygium afforded two additional compounds, (3R,4R)-3,4,5-trihydroxy-1-tetralone and tyrosol. Optically active compounds had their stereochemistry determined by circular dichroism (CD) spectroscopy.  相似文献   
9.
在砂土地层中,串囊式充气锚杆的研究还比较少,其承载特性及受力机理尚不明确。本文基于莫尔-库仑模型和Vesic圆孔扩张理论法,分别对圆柱体、球体、组合体、椭球体假设下的串囊式充气锚杆的扩大段进行计算分析。并将计算结果与试验得到的实测值进行对比。结果表明:四种形状假设中椭球体的形状假设理论值与实测值的误差最小,仅为8.35%。通过拟合试验数据,并引入与端阻力和侧摩阻力有关的两个系数对承载力公式进行修正,得到了抗拔承载力的经验公式。  相似文献   
10.
Red fluorescent carbon dots (R-CDs) are special desirable for biochemical analysis due to good biological compatibility and deep penetration; however, they remain as bottlenecks due to difficulties in expanding the sp2 domain, especially those are fused from rigid polycyclic conjugated molecules (RPCMs) with heteroatom substituents due to huge steric hindrance and heteroatom blockage toward graphic lattice. Here, an RPCM with heteroatom substituents, 1,5-diamino-4,8-dihydroxyanthraquinone (DDAQ), based self-doped R-CDs with PL emission at 635 nm is reported. Further investigations reveal that the expanding, hybrid sp2 domain with indanthrone tannin structure from DDAQ is mainly responsible for the obtained red fluorescence of R-CDs. Taking advantage of optical properties, R-CDs are considered to construct a colorimetric/fluorescent dual mode sensing array for quantifying trace levels of Fe3+ and glyphosate based on the static quenching, and a biomarker for cell imaging. The CD-based sensors exhibit outstanding recovery, high selectivity, and sensitivity, also facilitated dual-mode detection with the naked-eye. The R-CDs have low cytotoxicity, good cell membrane penetration for rapid cell entry, and high resolution, demonstrating their potential for biolabeling and bioanalytic applications.  相似文献   
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