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An online method to determine chlorine stable isotope composition by continuous flow isotope ratio mass spectrometry (CF-IRMS) coupled with a Gasbench Ⅱ 被引量:3
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作者 刘运德 周爱国 +3 位作者 甘义群 刘存富 余婷婷 李小倩 《Journal of Central South University》 SCIE EI CAS 2013年第1期193-198,共6页
An online method using continuous flow isotope ratio mass spectrometry (CF-IRMS) interfaced with a Gasbench Ⅱ was presented to determine chlorine stable isotope composition. Silver chloride (AgCl) was quantitativ... An online method using continuous flow isotope ratio mass spectrometry (CF-IRMS) interfaced with a Gasbench Ⅱ was presented to determine chlorine stable isotope composition. Silver chloride (AgCl) was quantitatively derived from chloride by using silver nitrate (AgNO3), and then was reacted with iodomethane (CH3Ⅰ) to produce methyl chloride (CH3Cl). A GasBench Ⅱ equipped with a PoraPlot Q column was used to separate CH3Cl from any other gas species. Finally, chlorine stable isotope analysis was carried out on CH3Cl introduced to the IRMS in a helium stream via an active open split. The minimum amount of Cl used in this method is of the order of 1.4 μmol. Inter-laboratory and inter-technique comparisons show that the total uncertainty incorporating both the precision and accuracy of this method is better than 0.007%. Furthermore, ten seawaters sampled from different locations have a narrow δ37Cl value range from -0.008% to 0.010%, with a mean value of (0.000±0.006)%. This supports the assumption that any seawater can be representative of standard mean ocean chloride (SMOC) and used as an international reference material. 展开更多
关键词 chlorine stable isotope continuous flow isotope ratio mass spectrometry CF-IRMS GasBench
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Robot系统测定旱地N_(2)排放的方法优化及其与其他方法的对比研究 被引量:1
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作者 李承霖 魏志军 +2 位作者 吴敏 单军 颜晓元 《土壤学报》 CAS CSCD 北大核心 2023年第3期694-704,共11页
反硝化是生态系统氮循环的最后一环同时也是活性氮转化为惰性氮(N2)的最主要过程。由于空气中背景N2浓度高达78%,在如此高的背景浓度N2环境中直接和准确测定反硝化过程产生的微量N2,一直是个巨大的挑战。Robot系统(Robotized incubation... 反硝化是生态系统氮循环的最后一环同时也是活性氮转化为惰性氮(N2)的最主要过程。由于空气中背景N2浓度高达78%,在如此高的背景浓度N2环境中直接和准确测定反硝化过程产生的微量N2,一直是个巨大的挑战。Robot系统(Robotized incubation and analyzing system)是基于无N2背景(氦环境)的用以研究纯菌或土壤体系N2排放速率的方法,该系统平台搭建简单且测定效率高,目前应用比较广泛。但该系统在运行过程中需要频繁利用微量注射器进行取样和测定,极易造成外界N2的渗漏。为解决这一问题,通过使用预先置于氦环境的橡胶隔垫、采用充氦后的蒸馏水配制溶液及实施破坏性取样的处理,对Robot系统测定旱地N2排放速率的方法进行优化,同时与乙炔抑制法和RoFlow系统(Robotized continuous flow incubation system)的测定结果进行对比。研究结果表明,通过方法优化,可以大幅降低Robot系统的N2渗漏率,方法优化后系统的渗漏率在0~0.78μL·L^(–1)·h^(–1)之间。优化后的Robot系统对碳源和氮源添加后N2排放速率差异的响应较好,并且对旱地土壤N2排放速率的测定误差最小(0.003~0.045 mg·kg^(–1)·d^(–1)),显著优于乙炔抑制法(0.34~3.29 mg·kg^(–1)·d^(–1))和RoFlow系统(0.41~1.02 mg·kg^(–1)·d^(–1))。综上,优化后的Robot系统在测定旱地N2排放速率时具有N2渗漏率低,对外源底物添加响应好及测定结果精确度高的特点,未来在研究旱地土壤背景N2排放及相关机理方面有较好的应用前景。 展开更多
关键词 N_(2)排放 乙炔抑制法 Robot系统(Robotized incubation and analyzing system) Roflow系统(Robotized continuous flow incubation system)
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Construction of a 3D meso-structure and analysis of mechanical properties for deposit body medium 被引量:1
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作者 石崇 陈凯华 +3 位作者 徐卫亚 张海龙 王海礼 王盛年 《Journal of Central South University》 SCIE EI CAS CSCD 2015年第1期270-279,共10页
For deposit body medium, the internal structural properties may be the controlling factors for the strength of the material and the mechanical response. Based on the results of soil-rock meso-statistics using digital ... For deposit body medium, the internal structural properties may be the controlling factors for the strength of the material and the mechanical response. Based on the results of soil-rock meso-statistics using digital imaging, a simulated annealing algorithm is adopted to expand the meso-structural features of deposit bodies in 3D. The construction of the 3D meso-structure of a deposit body is achieved, and then the particle flow analysis program PFC3 D is used to simulate the mechanical properties of the deposit body. It is shown that with a combination of the simulated annealing algorithm and the statistical feature functions, the randomness and heterogeneity of the rock distribution in the 3D inner structure of deposit body medium can be realized, and the reconstructed structural features of the deposit medium can match the features of the digital images well. The spatial utilizations and the compacting effects of the body-centered cubic, hexagonal close and face-centered packing models are high, so these structures can be applied in the simulations of the deposit structures. However, the shear features of the deposit medium vary depending on the different model constructive modes. Rocks, which are the backbone of the deposit, are the factors that determine the shear strength and deformation modulus of the deposit body. The modeling method proposed is useful for the construction of 3D meso-scope models from 2D meso-scope statistics and can be used for studying the mechanical properties of mixed media, such as deposit bodies. 展开更多
关键词 deposit body mesomechanical mode model continuation simulated annealing algorithm granular flow method
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