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101.
102.
Alfi Khatib Vikneswari Perumal Qamar Uddin Ahmed Bisha Fathamah Uzir Faridah Abas Suganya Murugesu 《Analytical letters》2017,50(12):1977-1991
Momordica charantia is widely consumed edible fruit. The food and pharmaceutical industries use it as a natural antioxidant. However, the quality control of M. charantia-based medicinal products is questionable due to the complexity of metabolites in this fruit. Hence, this study has developed a statistical model in predicting the antioxidant value through the 2, 2-diphenyl-1 picrylhydrazyl radical scavenging activity and ferric reducing antioxidant power based on infrared spectroscopy with attenuated total reflectance. This technique was reliably used for quality control. Six ethanol extracts (0, 20, 40, 60, 80, and 100% in water) of this plant’s fruit were prepared. The radical scavenging and ferric reducing antioxidant power activities were measured and the chemical profiling of the extracts was fingerprinted by infrared spectroscopy between 4,000 and 600?cm?1 at a resolution of 4?cm?1. Statistical analysis was developed by correlating the bioactivity and infrared spectra of each extract using orthogonal partial least square discriminant analysis. The C–N, C?O, C–O, C–H, and OH infrared signals were positively correlated with biological activity. The antioxidant activity of the fruit of M. charantia may be due to the presence of several antioxidants that work synergistically. 相似文献
103.
由J. T. Pindera提出的平面isodyne法是散光法的一种发展。具有非破坏性直接测取受力物体内部应力的特点。不需要大功率的激光器,条纹清晰,无畸变,对于平面应力问题可以得到应力分量的全部信息。在复合材料力学、断裂力学和接触问题等领域有广泛的应用前景。文章闸述了该方法的原理和技术,并应用它得到一受三点弯曲荷载的有裂纹的复合材料梁粘结层的应力分布。 相似文献
104.
基于近红外光纤漫反射技术,利用偏最小二乘法分别建立了复方氯丙那林胶囊的三种药效成分盐酸氯丙那林、盐酸溴己新和盐酸去氯羟嗪的快速同时测定方法。所建立的盐酸氯丙那林、盐酸溴己新和盐酸去氯羟嗪的定量分析多元校正模型的相关系数分别为99.7%、99.4%和99.0%,校正集的均方根残差分别为0.028、0.145和0.250,预测均方根误差分别为0.055、0.120和0.210。由于该方法是在不经任何预处理的情况下的光纤快速同时分析,因此可用于复方氯丙那林的过程质量控制。 相似文献
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107.
研究了采用电感耦合等离子体-原子发射光谱法(ICP-AES)测定油田水中铜、锌、锰、镍、铬、铁、锶、钡8种元素的方法.方法检出限为0.0003-0.0048μg·mL-1,回收率在96.7%-102.0%之间,相对标准偏差为0.77%-3.57%.采用该方法对油田水样进行了分析,结果表明精密度和准确度均满足分析要求. 相似文献
108.
H. Qi D.L. Wang L.M. Ruan 《Journal of Quantitative Spectroscopy & Radiative Transfer》2011,112(15):2507-2519
Particle Swarm Optimization (PSO) algorithms, including standard PSO, Stochastic PSO, and Multi-Phase PSO, are applied to solve the time-domain inverse transient radiation problems in the present research. Time-resolved transmittance and reflectance signals of four different measuring models serve as the measurement data, which estimate absorption, scattering coefficients, and geometric position within one-dimensional non-homogeneous media by inverse simulation. To check retrieval performances and accuracies of PSO-based approaches, four different inverse transient radiation cases are investigated to deal with one homogeneous layer, two-layer, three-layer, and continuous non-homogenous media. The influences of different searching ranges, swarm sizes, and maximum fly velocities on the fitness function of PSO are discussed. Meanwhile, the effects of measurement errors on the reconstruction accuracy are also investigated. All the results confirm that radiative parameters could be estimated accurately with measurement noise using PSO-based approaches. 相似文献
109.
利用积分球绝对测量法,对在20 Pa真空缺氧、1 000 Pa空气,105 Pa空气及1 000 Pa氧气环境下,1 064 nm波长连续激光辐照30CrMnSiA碳钢材料过程中的反射光信号进行了测量,得到了30CrMnSiA碳钢在4种辐照环境下的反射率和温度变化曲线。结果表明:在空气组分辐照环境的低压到105 Pa范围内,材料初始反射率随压力增大而增大;在缺氧和富氧环境的激光辐照过程中,缺氧环境下材料反射率变化缓慢,且变化拐点温度高于富氧环境,富氧环境下材料被加热后的快速氧化反应有利于材料对激光能量的吸收;不同辐照环境(缺氧和富氧)相同材料温度条件下,材料反射率并不相同。 相似文献
110.
Xiao-Fei ZhangQing Xu Han-Xing LiuWen Chen Min Chen Bok-Hee Kim 《Physica B: Condensed Matter》2011,406(8):1571-1576
Nonlinear dielectric properties of Ba0.6Sr0.4TiO3 ceramics prepared by citrate method were investigated under bias electric field with respect to field history. X-ray diffraction analysis and temperature dependence of the dielectric constant (εr) confirmed a macroscopically paraelectric state for the specimen at room temperature. A slim polarization versus electric field (P-E) hysteresis loop of the specimen at room temperature indicated the existence of polar nano-regions (PNRs) superimposed on the paraelectric background. The nonlinear dielectric properties in continuous cycles of bias field sweep displayed a strong sensitivity to the field history. This phenomenon was qualitatively explained in terms of an irreversible polarization evolution of the PNRs under the bias fields. A considerable decline of the tunability with the cycle number suggests an appreciable contribution of the PNRs to the dielectric nonlinearity. The polarization and size of the PNRs were determined by fitting the dielectric constants to a multipolarization mechanism model. 相似文献