低剂量氚照射对仔鼠中枢神经系统的影响及其机理研究

C57BL/6J小鼠妊娠12.5 d和Wistar大鼠妊娠13.0 d时,单次腹腔注射氚水,活度分别为0、24.09×10⁴、48.18×10⁴和144.54×10⁴ Bq/g,探讨低剂量氚照射对仔鼠中枢神经系统的影响及其机理。结果发现:(1)出生前氚照射可导致出生后生长发育受阻,神经行为早期的兴奋状态转为后期的抑制状态,学习能力及记忆功能明显下降;(2)大脑和小脑皮质厚度变薄,锥体细胞数减少,初级和次级树突数和比值明显减少,海马锥体细胞数减少以及脑神经元细胞缺失;(3)脑垂体生长抑素增高,下丘脑精氨酸加压素减少;(4)发育中的神经元表现出Ca²⁺电流降低,凋亡增加,DNA梯状图谱以及p53蛋白表达增高;(5)56项生物学指标中,45项致畸阈值在0.03～0.092 Gy范围内,11项致畸阈值在0.093～0.30 Gy范围内。结论认为,氚辐射导致中枢神经系统损伤的物质基础主要是脑神经活性物质改变、海马神经元Ca²⁺电流幅度下降、脑细胞凋亡增加、p53蛋白表达异常等。     

乳粉酸度测定的不确定度分析

通过建立采用GB/T 5009.46-2003乳制品酸度测定的不确定度评定的数学模型,对检测过程中引入的不确定度进行了分类和量化,较为全面的评定了各个不确定度分量,并提出了应用该方法检测的不确定度评定结果.     

Nonlinear effects and nonthermal plasmas

In view of the unique approach to solve the problems of nonradioactive nuclear energy production by the nonthermal migma concept, some critical remarks to the established plasma theory are given. The success of the many particle simulation, of the kinetic theory, and of the hydrodynamic theory is enormous but mostly limited to homogeneous and collisionless plasmas. Especially at laser interaction, the neglection of collisions close to the poles of the functions involved leads to drastic differences. Nonlinear effects enforced an extension of the hydrodynamic theory and the inhomogeneity required the generalization to non-space-charge-neutral plasmas. Together with collisions, numerous properties of plasma were derived indicating new resonances and the nonthermalised state of plasma at laser irradiation. These examples were to demonstrate the need for developing more basic plasma theory and why migma requires a very unconventional approach.     

Colorimetric ELISA based on glucose oxidase-regulated the color of acid–base indicator for sensitive detection of aflatoxin B1 in corn samples

This study described a sensitive direct competitive enzyme-linked immunosorbent assay (ELISA) for naked-eye detection of aflatoxin B₁ (AFB₁) by using glucose oxidase (GOx)-regulated bromocresol purple (BCP) color change. GOx was used as an alternative to horseradish peroxidase (HRP) for oxidization of glucose into hydrogen peroxide and gluconic acid. BCP, whose color is significantly sensitive to pH variation, was used as a signal output. Under optimal conditions, the developed method exhibited a considerably high sensitivity for AFB₁ detection with a cutoff limit of 100 pg/mL by the naked eye. The reliability of the developed colorimetric ELISA using naked-eye detection showed no false negative and false positive results among 70 AFB₁ spiked tests. Furthermore, the developed method showed a good linear range of 25–200 pg/mL for AFB₁ quantitative detection with a half-maximal inhibitory concentration at 66.72 pg/mL, which was approximately 10-fold lower than that of conventional HRP-based ELISA (IC₅₀ = 707 pg/mL). The recoveries from four kinds of AFB₁-spiked concentrations in corn extract solutions ranged within 80.56%–108.53%, with a coefficient of variation range of 1.69%–11.86%. These results exhibited good agreement with those of LC–MS/MS method indicating an acceptable accuracy and precision for AFB₁ quantitative detection in actual corn samples. In brief, this study was the first to use a GOx-mediated color change of BCP in immunoassay for naked-eye detection of AFB₁. This study also provided a new method for high-throughput screening detection of other small molecular chemicals using naked eye in resource-constrained countries.     

重组酶介导的等温扩增技术联合CRISPR-Cas13a快速检测4种腹泻病原菌

目的重组酶介导的等温扩增技术(RAA)联合规律间隔性成簇短回文重复序列相关Cas13a蛋白(CRISPR-Cas13a),建立对沙门菌、志贺菌、霍乱弧菌、肠出血性大肠杆菌O157:H7 4种腹泻病原菌的快速分子检测方法,即RAA-Cas13a。方法 设计4种腹泻病原菌的RAA特异性引物和CRISPR RNA(crRNA),利用RAA技术扩增样本核酸,并进行CRISPR-Cas13a恒温荧光检测,以实时荧光定量聚合酶链式反应(RT-qPCR)为对照方法,评价RAA-Cas13a优化方法的灵敏度与特异性。结果 RAA-Cas13a方法可在35 min内完成检测。检测志贺菌、霍乱弧菌、肠出血性大肠杆菌O157:H7的最低检测限为10 copies/μL,沙门菌最低检测限为1 copy/μL;特异性实验表明每一种病原菌与其余10种对照细菌均无交叉反应。应用建立的方法检测200份实际样本和40份人工污染样本,结果表明同RT-qPCR检测结果一致性高(分别为Kappa=0.927和Kappa=1.000)。结论 RAA-Cas13a检测方法具有灵敏度高,特异性强等优点,能用于4种腹泻病原菌的快速检...     

基于级联卷积神经网络的荧光免疫层析图像峰值点定位方法研究

针对目前荧光免疫层析定量图像峰值点定位易受多种因素影响,导致物质定量准确度低的问题,提出了一种融合目标检测的级联卷积神经网络(CNN)算法。第一层级联算法首先使用经改进的AlexNet算法对荧光免疫层析定量图像中包含质控(C)峰和检测(T)峰的区域进行检测和提取。之后将提取到的图像区域送入第二层级联卷积神经网络中,对C峰和T峰的位置进行快速定位。随后将定位结果输入到第三层级联卷积神经网络中,对上一层输出的C峰和T峰的定位结果进行精准微调。最后输出C峰和T峰的准确定位信息。实验结果表明,提出的级联卷积神经网络算法,对荧光免疫层析图像峰值点的平均定位准确度达到了96%以上,提高了峰值点的定位准确度。     

Application of chaos and fractal models to water quality time series prediction

This paper established a global chaos model to predict water quality time series that comprised a small amount of data, and the reducing-dimension chaos method was put forward to improve calculation of the global chaos method. Furthermore, sectioned variable-dimension fractal was also used to simulate and predict the same water quality time series. To investigate the prediction ability of the two chaos methods and fractal method, the auto regression (AR) model and grey model were used. The results illustrated that prediction accuracy of the global chaos method and the reducing-dimension method was higher than that of the AR model and grey model. The prediction result of the reducing-dimension method was the most satisfactory among the five methods. The results also indicated that the prediction accuracy of sectioned variable-dimension fractal method was better than that of the AR and grey methods.