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71.
72.
A novel and highly sensitive colorimetric sensor array was developed for the detection and identification of breath volatile organic compounds(VOCs) of patients with lung cancer.Employing dimeric metalloporphyrins,metallosalphen complexes,and chemically responsive dyes as the sensing elements,the developed sensor array of artificial nose shows a unique pattern of colorific changes upon its exposure to eight less-reactive VOCs and their mixture gas at a concentration of 735 nmol/L within 3 min.Potential of quantitative analysis of VOCs samples was proved.A good linear relationship of 490-3675 nmol/L was obtained for benzene vapor with a detection limit of 49 nmol/L(S/N=3).Data analysis was carried out by Hierarchical cluster analysis(HCA) and principal component analysis(PCA).Each category of breath VOCs clusters together in the PCA score plot.No errors in classification by HCA were observed in 45 trials.Additionaly,the colorimetric sensor array showed good reproducibility under the cyclic sensing experiments.These results demonstrate that the developed colorimetric artificial nose system is an excellent sensing platform for the identification and quantitative analysis of breath VOCs of patients with lung cancer. 相似文献
73.
以纳米碳酸钙为核体,用聚电解质对其表面改性后,采用均相共沉淀法制备了锡掺杂氧化铟(ITO)包覆的碳酸钙基浅色导电粉.通过改变聚电解质层数、ITO的包覆量及煅烧时间等实验条件,探究了制备纳米碳酸钙基浅色导电粉的最佳条件.用X-射线粉末衍射仪、扫描电子显微镜、X-射线电子能谱以及粉末电阻率测试仪等对样品的结构、形貌、化学组成及电阻率等进行分析.结果表明:聚电解质层数为5层,CaCO3与ITO的质量比为6∶1,500℃煅烧4.5h制备的粉末具有最佳的导电性能,其电阻率为3.8×103 Ω·cm. 相似文献
74.
75.
以具有自治系统一般形式的运动方程及其相应的Fokker-Planck方程为出发点,确立了一种适应面比较广的耗散系统的准热力学模型.定义了与驱动项f相共轭的函数X,取代作为上述运动方程的自田变量x(x可代表某种输出或化学反应的产物).以状态参量f,X,C(C为控制参量)对照参量p,V,T,得到一系列涉及准热力学函数及其导数的基本关系式,它们与传统热力学是一一对应的,最后给出一个应用范例.
关键词: 相似文献
76.
Mohamed FB Vinitski S Gonzalez CF Faro SH Lublin FA Knobler R Gutierrez JE 《Magnetic resonance imaging》2001,19(2):207-218
MRI is a very sensitive imaging modality, however with relatively low specificity. The aim of this work was to determine the potential of image post-processing using 3D-tissue segmentation technique for identification and quantitative characterization of intracranial lesions primarily in the white matter. Forty subjects participated in this study: 28 patients with brain multiple sclerosis (MS), 6 patients with subcortical ischemic vascular dementia (SIVD), and 6 patients with lacunar white matter infarcts (LI). In routine MR imaging these pathologies may be almost indistinguishable. The 3D-tissue segmentation technique used in this study was based on three input MR images (T(1), T(2)-weighted, and proton density). A modified k-Nearest-Neighbor (k-NN) algorithm optimized for maximum computation speed and high quality segmentation was utilized. In MS lesions, two very distinct subsets were classified using this procedure. Based on the results of segmentation one subset probably represent gliosis, and the other edema and demyelination. In SIVD, the segmented images demonstrated homogeneity, which differentiates SIVD from the heterogeneity observed in MS. This homogeneity was in agreement with the general histological findings. The LI changes pathophysiologically from subacute to chronic. The segmented images closely correlated with these changes, showing a central area of necrosis with cyst formation surrounded by an area that appears like reactive gliosis. In the chronic state, the cyst intensity was similar to that of CSF, while in the subacute stage, the peripheral rim was more prominent. Regional brain lesion load were also obtained on one MS patient to demonstrate the potential use of this technique for lesion load measurements. The majority of lesions were identified in the parietal and occipital lobes. The follow-up study showed qualitatively and quantitatively that the calculated MS load increase was associated with brain atrophy represented by an increase in CSF volume as well as decrease in "normal" brain tissue volumes. Importantly, these results were consistent with the patient's clinical evolution of the disease after a six-month period. In conclusion, these results show there is a potential application for a 3D tissue segmentation technique to characterize white matter lesions with similar intensities on T(2)-weighted MR images. The proposed methodology warrants further clinical investigation and evaluation in a large patient population. 相似文献