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991.
基于荧光猝灭原理的硝基芳烃类爆炸物检测实验研究 总被引:1,自引:1,他引:0
基于荧光猝灭原理,以共轭荧光聚合物MEH-PPV为荧光指示剂,采用塑料光纤作为传感和传光元件进行硝基芳烃类爆炸物检测。实验采用探测荧光指示剂荧光寿命的方法进行爆炸物检测,荧光指示剂的荧光寿命利用相移法进行测量。测量了不同荧光指示剂浓度时系统对爆炸物检测的灵敏度,发现当MEH-PPV质量浓度为10 mg/L时,系统的灵敏度最高;研究了U形、双锥形、螺旋形塑料光纤传感头对系统灵敏度的影响,发现双锥形传感头的灵敏度最高;测试了荧光指示剂MEH-PPV的稳定性,实验表明光照会加快MEH-PPV的漂白速度。 相似文献
992.
Dong-Hau Kuo Yung-Chuan Chen Jheng-Yu He Jinn P. Chu 《Journal of Electronic Materials》2011,40(6):1345-1349
Intermetallic nanocrystal memory devices with nickel aluminide nanocrystals in the electron-trapping layer and an alumina
layer as the blocking layer were prepared on the surface of oxidized silicon substrates by sputter-coating of Ni and Al2O3 in sequence, followed by an annealing procedure. Several aluminide nanocrystal memory devices are reported. The effect of
annealing at 900°C on the memory properties was investigated. Intermetallic nanocrystals were identified by high-resolution
transmission electron microscopy and x-ray photoelectron spectroscopy as Ni2Al3 with sizes of 15–20 nm. The results showed that a sixfold increase (0.37 V to 2.34 V) in the memory window could be achieved
after annealing for the optimal time of 3 min. 相似文献
993.
Meyer TE Fox SD Issaq HJ Xu X Chu LW Veenstra TD Hsing AW 《Analytical chemistry》2011,83(14):5735-5740
While sarcosine was recently identified as a potential urine biomarker for prostate cancer, further studies have cast doubt on its utility to diagnose this condition. The inconsistent results may be due to the fact that alanine and sarcosine coelute on an HPLC reversed-phase column and the mass spectrometer cannot differentiate between the two isomers, since the same parent/product ions are generally used to measure them. In this study, we developed a high-throughput liquid chromatography-mass spectrometry (LC-MS) method that resolves sarcosine from alanine isomers, allowing its accurate quantification in human serum and urine. Assay reproducibility was determined using the coefficient of variation (CV) and intraclass correlation coefficient (ICC) in serum aliquots from 10 subjects and urine aliquots from 20 subjects across multiple analytic runs. Paired serum/urine samples from 42 subjects were used to evaluate sarcosine serum/urine correlation. Both urine and serum assays gave high sensitivity (limit of quantitation of 5 ng/mL) and reproducibility (serum assay, intra- and interassay CVs < 3% and ICCs > 99%; urine assay, intra-assay CV = 7.7% and ICC = 98.2% and interassay CV = 12.3% and ICC = 94.2%). In conclusion, this high-throughput LC-MS method is able to resolve sarcosine from α- and β-alanine and is useful for quantifying sarcosine in serum and urine samples. 相似文献
994.
Deuterated potassium dihydrogen phosphate (DKDP) crystal is one of the most commonly used electro-optical (EO) Q-switch materials. A traditional DKDP EO Q-switch in the Pockels cell has a pair of electrodes, resulting in a nonuniform electric potential along the radial direction. Theoretical analysis and calculation show the radial nonuniform electric potential of DKDP crystals can be improved by adding a pair of auxiliary electrodes. Meanwhile, the experimental results demonstrate that the Q-switched laser characteristics are greatly improved with auxiliary electrodes added to DKDP crystal. 相似文献
995.
A novel synthetic process has been developed to fabricate the magnetic alloy/spinel ferrite composite nanofibers. By employing the electrospinning technique and subsequent partial reduction, Fe-Ni alloy/nickel ferrite composite nanofibers with an average diameter of around 170 nm were successfully prepared. The synthesized composite nanofibers consist of the face centered cubic and body centered cubic phases of Fe-Ni alloy and the spinel phase of nickel ferrite, and have novel magnetic properties with much enhanced coercivity and saturation magnetization as compared with the pristine nickel ferrite nanofibers. 相似文献
996.
以湖南省炎汝高速公路梅子山隧道为依托,根据冲沟段的地形地质条件,通过数值模拟研究浅埋偏压和拱部出露两种情况的施工力学行为,辨识施工中存在的不利因素,进行施工风险分析,提出隧道穿越冲沟段施工存在塌方、大变形、渗漏水、边仰坡失稳等风险事件,并有针对性地提出风险控制措施.结合现场施工与监测情况,讨论现场实施效果,洞内外变形正... 相似文献
997.
998.
Yu-Pin Lin Chi-Ru Chang Hone-Jay Chu Bai-You Cheng 《Landscape and urban planning》2011,102(3):156-163
This study utilized a finite mixture distribution model (FMDM) to identify the distribution of bird diversity in urban and suburban areas of the Taipei basin. The spatial patterns of Shannon's diversity index were estimated using Sequential Gaussian simulation (SGS) with bird investigation data. To validate the results of FMDM, bird groups were classified by two-way indicator species analysis (TWINSPAN) based on bird presence-absence records. The probabilities exceeding FMDM's cut-off values for suburban bird communities were obtained from SGS realizations. The results showed that bird diversity in the Taipei basin could be comprised of two-component mixture distributions for urban and suburban bird communities, respectively. The FMDM bird diversity classifications fit the TWINSPAN groups of urban and suburban species. The spatial maps of bird diversity in the study area provide evidence that a metropolis can cause changes in the spatial characteristics of bird communities at the landscape level. Furthermore, the bird diversity and land use maps could be useful for future conservation and urban planning in Taipei Basin, particularly urban green spaces and wetlands. The maps could also be utilized in network planning of green belts or corridors for ecological conservation. 相似文献
999.
循环载荷作用下盐岩力学特性响应研究 总被引:1,自引:0,他引:1
通过模拟储气库运行围岩受载情况,对层状盐岩储气库围岩中常见盐岩及含夹层盐岩进行应力水平不断提高的反复加卸载试验研究。试验结果表明:与单调加载相比,循环载荷下芒硝试样强度明显降低;含钙质泥岩夹层芒硝的强度高于纯芒硝,但由于受夹层的影响,峰值点对应应变低于纯芒硝。与其他岩石明显不同,在初期阶段,盐岩试样循环加卸载曲线基本呈线性并重叠,随应力水平及循环次数的提高,滞回环现象有轻微表现,但面积很小。后期卸载过程中盐岩的杨氏模量略高于加载过程,除卸载过程弹性变形恢复滞后外,还受加载过程中耦合的塑性变形因素影响。由于钙质泥岩夹层的变形能力相对较弱,含夹层芒硝的杨氏模量稍高于芒硝,同时,在反复循环卸载过程中的变形恢复也大于纯盐岩。总体上看,盐岩在加卸载过程中杨氏模量基本不随应力水平及加卸载次数的变化而变化。同时,即使进入屈服破坏阶段,也没有出现一般岩土材料加卸载杨氏模量随屈服应力降低而降低的现象。根据能量观点分析,循环载荷作用下强度降低幅度与循环次数及累积滞回环面积相关。本次试验中,5个试样循环加卸载作用过程中,加卸载曲线几乎重合,滞回环很小,因而强度降幅也很小。据此推断,在储气库反复加卸载运行过程中,围岩强度基本不会受循环次数的影响;但大幅度的压力波动有可能产生能量累积,从而影响其强度与寿命。 相似文献
1000.
城市的快速发展引发了一系列"交通问题"。针对"交通问题"的系统性、复杂性、可借鉴"针灸"的原理,从关键地段、关键建筑入手。在建筑方案设计中,建筑师需建立"建筑、交通一体化"观念,将"城市交通"作为内在要素纳入建筑设计范畴综合考虑,实现在"车行主导"背景下高质量地"步行融入"——这既是对城市本质目标最切实的回应,也是当下的一种建筑师策略与意识。 相似文献