叶绿素浓度是海洋初级生产力的重要指标之一,激光诱导荧光技术可以实现海水叶绿素浓度的快速测量。测量叶绿素浓度的传统激光诱导荧光原理,是利用叶绿素荧光与水体Raman散射的强度比值( I F/ R)进行反演,即叶绿素浓度 n chl=CI F/R,其中...叶绿素浓度是海洋初级生产力的重要指标之一,激光诱导荧光技术可以实现海水叶绿素浓度的快速测量。测量叶绿素浓度的传统激光诱导荧光原理,是利用叶绿素荧光与水体Raman散射的强度比值( I F/ R)进行反演,即叶绿素浓度 n chl=CI F/R,其中 C 为系统常量。这是依据叶绿素荧光685 nm、水体Raman散射强度都与激发光强呈线性关系。然而,该理论并没有考虑诱导荧光饱和现象的存在。当诱导激光强度达到一定程度后, 685 nm荧光强度随激发光强非线性变化。另外,值得注意的是,水体Raman散射并不存在信号饱和现象。为了探讨饱和激发造成荧光非线性变化的影响,在激光诱导荧光技术测量叶绿素浓度的实验中,设计两种测量方案,即:不同激光功率诱导单一浓度样本的荧光测量,和固定激光功率时不同浓度样本的荧光测量。实验中利用Nd∶YAG三倍频激光355 nm激发获得叶绿素溶液的404 nm处 Raman散射和685 nm荧光。实验结果分为2部分进行讨论:(1)为了分析饱和激发造成荧光变化的非线性特性,通过调节激发光功率测量溶液的受激发射光谱,发现水体Raman散射强度与激发光强呈线性关系,而685 nm荧光强度出现饱和激发下的非线性变化。而且,随叶绿素浓度的增加, 685 nm荧光的非线性趋势更为明显, Raman散射强度与激发光强的线性关系中斜率变小。数据分析表明, 685 nm荧光数据拟合的4阶多项式和Raman散射效率值,可以定性地表征685 nm荧光的饱和程度。(2)考虑实际海洋激光雷达探测叶绿素浓度应用中存在饱和激发荧光非线性现象,为了分析荧光非线性对传统叶绿素浓度反演理论适用性的影响,在固定激发光强情况下对不同浓度叶绿素溶液的发射光谱进行测量。将激发光功率调节至52.00, 80.70, 132.10和197.30 mW·cm^-2 ,获取相应激发光强下685 nm荧光与水体Raman散射的强度比值和叶绿素浓度之间的关系。实验表明,激发光强不变的情况下, 685 nm荧光与水体Raman散射的强度比值,与叶绿素浓度仍满足线性关系。但是,在较高光强激发时,饱和激发造成的叶绿素荧光非线性变化,导致利用传统激光诱导荧光理论反演的叶绿素浓度值偏小。因此,需要对饱和激发下荧光非线性的影响进行修正,其关系为 I F / R=n chl / C + C F,修正值 C F不可忽略。另外,值得一提的是,修正关系中系统常量 C 随激发光强增加而增大。研究表明,饱和激发造成的荧光非线性,会对激光诱导荧光技术测量叶绿素浓度产生影响,但由于造成荧光非线性因素的复杂性,仅通过荧光数据拟合获得的多项式,无法定量说明其影响权重。然而,当激发光强不变时,可以实验测量获得基于激光诱导荧光原理的修正关系,从而准确反演叶绿素浓度。展开更多
荧光线性标记技术（Fluorescent linear labelling method）是一种有效、单试管、单一扩增的双色标记技术。样品RNA通过逆转录酶作用合成双链的cDNA，再应用T7RNA聚合酶合成cRNA，同时加入Cy3和Cy5标记的CTP，从而实现对核酸样品的标记...荧光线性标记技术（Fluorescent linear labelling method）是一种有效、单试管、单一扩增的双色标记技术。样品RNA通过逆转录酶作用合成双链的cDNA，再应用T7RNA聚合酶合成cRNA，同时加入Cy3和Cy5标记的CTP，从而实现对核酸样品的标记。由于荧光线性标记技术可以实现对初始样品50-100倍的扩增，并且线性度较好，因此在生物芯片实验的样品标记领域具有重要的应用价值。展开更多
O433.4 2004053299 <sup>127</sup>I<sub>2</sub>在532nm波段谱线的理论计算=Theoretical calculation of spectra for <sup>127</sup>I<sub>2</sub> near 532 nm[刊,中]/彭月祥（北...O433.4 2004053299 <sup>127</sup>I<sub>2</sub>在532nm波段谱线的理论计算=Theoretical calculation of spectra for <sup>127</sup>I<sub>2</sub> near 532 nm[刊,中]/彭月祥（北京交通大学理学院,北京（100044））,李文博…∥光电子·激光。—2003,14（11）,—1215-1218 报道了计算<sup>127</sup>I<sub>2</sub>展开更多
The synthetic route of N^2, 3-ethenoguanosine （ε-G） was described. Its ultraviolet and fluorescent properties at various pH were studied. These results indicate that ε-G dissociates a hydrogen ion to give the ani...The synthetic route of N^2, 3-ethenoguanosine （ε-G） was described. Its ultraviolet and fluorescent properties at various pH were studied. These results indicate that ε-G dissociates a hydrogen ion to give the anion ε-G and associates a hydrogen ion to give a the cation ε-GH~. The neutral specie ε-G is the origin of fluorescence. The fluorescent properties in different media were studied and there was most strong fluorescence in water. Based on fluorescencc quenching of ε-G on BSA, the binding constant and the number of binding sites between ε-G and BSA were determined, which were 1.78x10^3 L/mol and I, respectively. The quenching mechanism was discussed. It indicates that the powerful interaction exists between ε-G and BSA.展开更多
The objective of this work is to assess the radiation hazards associated gamma rays from building materials. Natural gamma rays activities of natural radionuclide represented mainly by three natural radioactive series...The objective of this work is to assess the radiation hazards associated gamma rays from building materials. Natural gamma rays activities of natural radionuclide represented mainly by three natural radioactive series ^238U, ^235U and ^232Th, and the primordial ^40K in the samples of building materials which consist of bricks, ceramics, marble and gypsum from different areas of eastern Algeria are measured using gamma ray spectrometry. The values of the activities of these radionuclides do not clearly reflect the radiation hazard associated with these materials. Therefore, the radium equivalent （Raeq） concentration is defined taking into account the effectiveness of these isotopes in creating the radiation hazard. Radium equivalent activities, external and internal hazard indices （Hex and Hin） are calculated from the activities of ^226Ra, ^232Th and ^40K for suitability of the materials.展开更多
文摘叶绿素浓度是海洋初级生产力的重要指标之一,激光诱导荧光技术可以实现海水叶绿素浓度的快速测量。测量叶绿素浓度的传统激光诱导荧光原理,是利用叶绿素荧光与水体Raman散射的强度比值( I F/ R)进行反演,即叶绿素浓度 n chl=CI F/R,其中 C 为系统常量。这是依据叶绿素荧光685 nm、水体Raman散射强度都与激发光强呈线性关系。然而,该理论并没有考虑诱导荧光饱和现象的存在。当诱导激光强度达到一定程度后, 685 nm荧光强度随激发光强非线性变化。另外,值得注意的是,水体Raman散射并不存在信号饱和现象。为了探讨饱和激发造成荧光非线性变化的影响,在激光诱导荧光技术测量叶绿素浓度的实验中,设计两种测量方案,即:不同激光功率诱导单一浓度样本的荧光测量,和固定激光功率时不同浓度样本的荧光测量。实验中利用Nd∶YAG三倍频激光355 nm激发获得叶绿素溶液的404 nm处 Raman散射和685 nm荧光。实验结果分为2部分进行讨论:(1)为了分析饱和激发造成荧光变化的非线性特性,通过调节激发光功率测量溶液的受激发射光谱,发现水体Raman散射强度与激发光强呈线性关系,而685 nm荧光强度出现饱和激发下的非线性变化。而且,随叶绿素浓度的增加, 685 nm荧光的非线性趋势更为明显, Raman散射强度与激发光强的线性关系中斜率变小。数据分析表明, 685 nm荧光数据拟合的4阶多项式和Raman散射效率值,可以定性地表征685 nm荧光的饱和程度。(2)考虑实际海洋激光雷达探测叶绿素浓度应用中存在饱和激发荧光非线性现象,为了分析荧光非线性对传统叶绿素浓度反演理论适用性的影响,在固定激发光强情况下对不同浓度叶绿素溶液的发射光谱进行测量。将激发光功率调节至52.00, 80.70, 132.10和197.30 mW·cm^-2 ,获取相应激发光强下685 nm荧光与水体Raman散射的强度比值和叶绿素浓度之间的关系。实验表明,激发光强不变的情况下, 685 nm荧光与水体Raman散射的强度比值,与叶绿素浓度仍满足线性关系。但是,在较高光强激发时,饱和激发造成的叶绿素荧光非线性变化,导致利用传统激光诱导荧光理论反演的叶绿素浓度值偏小。因此,需要对饱和激发下荧光非线性的影响进行修正,其关系为 I F / R=n chl / C + C F,修正值 C F不可忽略。另外,值得一提的是,修正关系中系统常量 C 随激发光强增加而增大。研究表明,饱和激发造成的荧光非线性,会对激光诱导荧光技术测量叶绿素浓度产生影响,但由于造成荧光非线性因素的复杂性,仅通过荧光数据拟合获得的多项式,无法定量说明其影响权重。然而,当激发光强不变时,可以实验测量获得基于激光诱导荧光原理的修正关系,从而准确反演叶绿素浓度。
文摘荧光线性标记技术（Fluorescent linear labelling method）是一种有效、单试管、单一扩增的双色标记技术。样品RNA通过逆转录酶作用合成双链的cDNA，再应用T7RNA聚合酶合成cRNA，同时加入Cy3和Cy5标记的CTP，从而实现对核酸样品的标记。由于荧光线性标记技术可以实现对初始样品50-100倍的扩增，并且线性度较好，因此在生物芯片实验的样品标记领域具有重要的应用价值。
文摘O433.4 2004053299 <sup>127</sup>I<sub>2</sub>在532nm波段谱线的理论计算=Theoretical calculation of spectra for <sup>127</sup>I<sub>2</sub> near 532 nm[刊,中]/彭月祥（北京交通大学理学院,北京（100044））,李文博…∥光电子·激光。—2003,14（11）,—1215-1218 报道了计算<sup>127</sup>I<sub>2</sub>
文摘The synthetic route of N^2, 3-ethenoguanosine （ε-G） was described. Its ultraviolet and fluorescent properties at various pH were studied. These results indicate that ε-G dissociates a hydrogen ion to give the anion ε-G and associates a hydrogen ion to give a the cation ε-GH~. The neutral specie ε-G is the origin of fluorescence. The fluorescent properties in different media were studied and there was most strong fluorescence in water. Based on fluorescencc quenching of ε-G on BSA, the binding constant and the number of binding sites between ε-G and BSA were determined, which were 1.78x10^3 L/mol and I, respectively. The quenching mechanism was discussed. It indicates that the powerful interaction exists between ε-G and BSA.
文摘The objective of this work is to assess the radiation hazards associated gamma rays from building materials. Natural gamma rays activities of natural radionuclide represented mainly by three natural radioactive series ^238U, ^235U and ^232Th, and the primordial ^40K in the samples of building materials which consist of bricks, ceramics, marble and gypsum from different areas of eastern Algeria are measured using gamma ray spectrometry. The values of the activities of these radionuclides do not clearly reflect the radiation hazard associated with these materials. Therefore, the radium equivalent （Raeq） concentration is defined taking into account the effectiveness of these isotopes in creating the radiation hazard. Radium equivalent activities, external and internal hazard indices （Hex and Hin） are calculated from the activities of ^226Ra, ^232Th and ^40K for suitability of the materials.
