Papers by Keyword: Nitrogen

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Authors: Ghassan Younes, Gabriel Ferro, Christophe Jacquier, Jacques Dazord, Yves Monteil
Authors: Ning Li Qi, Pu Wang Li, Xian Hai Zeng, Hong Hai Huang, Zi Ming Yang, Xiao Gong
Abstract: The nitrogen in raw natural rubber is mainly derived from crude protein of latex. In this study, the nitrogen content of six kinds of raw natural rubber was analyzed for evaluating Kjeldahl and elemental analysis methods. The nitrogen content ranged from 0.43% to 0.66% for Kjeldahl methods and from 0.45% to 0.75% for elemental analysis method. There was no significant difference between the two methods. The coefficient of variation was below 1%. The data of nitrogen content showed a simple linear correlation (r=0.9937) between the two methods. It was concluded that the elemental analysis method could replace Kjeldahl method in nitrogen analysis of raw natural rubber.
Authors: K. Chatty, V. Khemka, T. Paul Chow, Ronald J. Gutmann
Authors: Yong Gang Zeng, Lin Chen, Hai Xia Li, Jin Huang, Bo Yu
Abstract: This paper compared the measurement of ammonia and nitrogen in surface water by spectrophotometry and flow injection analysis, and the results indicate: Nessler method detection range of 0.02~2.0 mg/L, and detection limit is 0.02mg/L; flow injection detection range 0.01~ 10mg/L, and the detection limit is 0.001mg/L, 50 samples analyzed rate is 50 samples/h; flow injection is simple and in good linearity, and the sensitivity, precision and accuracy can meet the analytical requirement with better analysis speed, low consumption of reagents and samples, which is a sensitive, selective and friendly analysis method, which will be the future development trend.
Authors: A.A. Efremov, V.G. Litovchenko, A.V. Sarikov, Hans Richter, V.D. Akhmetov
Authors: T. Acartürk, Kurt Semmelroth, Gerhard Pensl, Stephen E. Saddow, Ulrich Starke
Abstract: The concentration of nitrogen and phosphorous in SiC bulk material and epitaxial layers was investigated using time-of-flight secondary ion mass spectrometry (TOF-SIMS). The advantage of TOF-SIMS of acquiring a complete mass spectrum in a single run was used to identify the most sensitive atomic ion or ionic cluster for the selected element to be monitored. For the investigation of N with its intrinsic low ionization yield the use of a Cs containing cluster ion is necessary. Selection of a CNCs2 + cluster allows to reach a detection limit of about cN,min » 5×1016 cm-3. In the case of P the elemental ion was used. However, the adjacent mass of 30SiH influences the P peak as well as its background and has to be suppressed. This can be achieved by limiting the residual gas re-adsorption during the measurement resulting in a detection limit of about cP,min » 5×1015 cm-3. These measurement parameters were used to investigate a single crystal SiC bulk sample grown by the modified Lely method with intentional P doping and an N doped epitaxial SiC layer sample.
Authors: E.R. Glaser, B.V. Shanabrook, W.E. Carlos, Hun Jae Chung, Saurav Nigam, A.Y. Polyakov, Marek Skowronski
Abstract: We have employed low-temperature photoluminescence to estimate the total residual N concentration in semi-insulating (SI) SiC substrates where all N shallow donors are compensated in the dark. The ratio of the nitrogen-bound exciton line (Qo) to the free excitonic emission (I77) as a function of excitation power density (Pexc) was tracked for several SI 4H-SiC samples with varying residual N concentration (~ 7x1014 – 5.2x1016 cm-3). Most notably, a linear relationship was found between Qo/I77 and [N] for [N] < 1x1016 cm-3 while a sub-linear behavior was observed for samples with higher N levels. This technique should be particularly valuable to map [N] where the levels are close to or below the present SIMS detection limit of ~ 5-7 x 1014 cm-3. Results obtained for a limited number of low n-type and SI 6H-SiC substrates are also presented.
Authors: Ji Guang Li, Hui Sun, Min Tao, Qi Shuo Wang, Wei Ming Tan, Wei Xie, Zhen Hua Liu
Abstract: The global environment change is human beings are facing with the important and urgent environmental problems: in natural and human action double drive, the surface of the earth element biogeochemical process and its environmental effect is the current global change research in the area of the important content. In order to estimate and forecast geochemical cycle of change and to the global life support system influence, since the 1970s on the ecological system of the nitrogen cycle extensive and in-depth research, and in the process of this a series of ecological environment effect.Wetland biogeochemical process is refers to the carbon, hydrogen (water), oxygen, nitrogen, phosphorus and sulfur and various essential elements in the wetland soil and plant all kinds of migration between transformation and energy exchange process. Chemical process including nitrogen, phosphorus and other nutrients in the wetland system of flow and transformation, Wetland in heavy metals and other organic inorganic pollutants absorption, so close, transformation and enrichment, etc.
Authors: Ji Ku Zhang, Yue Lang, Ming Jie Li
Abstract: Experiment simulates the integrated vertical flow constructed wetland (IVCW) operation of the system, discusses the trend of Dissolved Oxygen (DO) within the system and the relativity of DO and removing nitrogen. The results show that NH4+-N, NO3—-N and DO decrease along the flow direction in the integrated vertical flow constructed wetlands; NO3—-N increased and then decreased along the process; because of the DO of upstream pool is low, so the Total Nitrogen (TN) removing process occurs mainly in the downstream pool.
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