Year-round atmospheric wet and dry deposition of nitrogen and phosphorus on water and land surfaces in Nanjing, China.

Science.gov (United States)

Sun, Liying; Li, Bo; Ma, Yuchun; Wang, Jinyang; Xiong, Zhengqin

2013-06-01

The dry deposition of ammonium, nitrate, and total phosphorus (TP) to both water (DW) and land (DD) surfaces, along with wet deposition, were simultaneously monitored from March 2009 to February 2011 in Nanjing, China. Results showed that wet deposition of total phosphorus was 1.1 kg phosphorus ha (-1)yr(-1), and inorganic nitrogen was 28.7 kg nitrogen ha (-1)yr(-1), with 43% being ammonium nitrogen. Dry deposition of ammonium, nitrate, and total phosphorus, measured by the DW/DD method, was 7.5/2.2 kg nitrogen ha (-1)yr(-1), 6.3/ 4.9 kg nitrogen ha (-1)yr(-1), and 1.9/0.4 kg phosphorus ha (-1)yr(-1), respectively. Significant differences between the DW and DD methods indicated that both methods should be employed simultaneously when analyzing deposition to aquatic and terrestrial ecosystems in watershed areas. The dry deposition of ammonium, nitrate, and total phosphorus contributed 38%, 28%, and 63%, respectively, to the total deposition in the simulated aquatic ecosystem; this has significance for the field of water eutrophication control.

Reducing dissolved inorganic nitrogen in surface runoff water from sugarcane production systems.

Science.gov (United States)

Webster, A J; Bartley, R; Armour, J D; Brodie, J E; Thorburn, P J

2012-01-01

Nitrogen (N) lost from farms, especially as the highly bioavailable dissolved inorganic form, may be damaging Australia's Great Barrier Reef (GBR). As sugarcane is the dominant cropping system in GBR catchments, its N management practises are coming under increasing scrutiny. This study measured dissolved inorganic N lost in surface runoff water and sugarcane productivity over 3 years. The experiment compared the conventional fertiliser N application rate to sugarcane (average 180kg N/ha/year) and a rate based on replacing N exported in the previous crop (average 94kg N/ha/year). Dissolved inorganic N losses in surface water were 72%, 48% and 66% lower in the three monitored years in the reduced N fertiliser treatment. There was no significant difference in sugarcane yield between the two fertiliser N treatments, nor any treatment difference in soil mineral N - both of these results are indicators of the sustainability of the lower fertiliser N applications. Copyright © 2012 Elsevier Ltd. All rights reserved.

Development of radioactive surface contamination monitor

International Nuclear Information System (INIS)

Hashimoto, Tadao; Hasegawa, Toru; Fukumoto, Keisuke; Ooki, Yasushi

2008-01-01

In the radiation facilities such as nuclear power plants, surface contamination of the people accessing or articles conveyed in and out of the radiation controlled areas is detected and monitored by installing contamination monitors at the boundary of controlled areas and uncontrolled areas against the expansion of the radioactive materials to out of the facilities. It is required for the surface contamination of articles to be tightened of control criteria as 'Guidelines for discrimination ways of nonradioactive waste (not classified as radioactive waste) generated from nuclear power plants' (hereinafter referred to as 'the Guideline') was established by the Nuclear and Industrial Safety Agency of the Ministry of Economy, Trade and Industry in August, 2005. It predicts that the control criteria of monitors other than article monitors are also tightened in the future. Fuji electric has been fabricating and delivering surface contamination detecting monitors. Now we are developing the new contamination monitor corresponding to the tightening of the control criteria. 'Large article transfer monitor', 'Clothing monitor' and 'Body surface contamination monitor' are introduced in this article. (author)

Monitoring plant tissue nitrogen isotopes to assess nearshore inputs of nitrogen to Lake Crescent, Olympic National Park, Washington

Science.gov (United States)

Cox, Stephen E.; Moran, Patrick W.; Huffman, Raegan L.; Fradkin, Steven C.

2016-05-31

Mats of filamentous-periphytic algae present in some nearshore areas of Lake Crescent, Olympic National Park, Washington, may indicate early stages of eutrophication from nutrient enrichment of an otherwise highly oligotrophic lake. Natural abundance ratios of stable isotopes of nitrogen (δ15N) measured in plant tissue growing in nearshore areas of the lake indicate that the major source of nitrogen used by these primary producing plants is derived mainly from atmospherically fixed nitrogen in an undeveloped forested ecosystem. Exceptions to this pattern occurred in the Barnes Point area where elevated δ15N ratios indicate that effluent from septic systems also contribute nitrogen to filamentous-periphytic algae growing in the littoral zone of that area. Near the Lyre River outlet of Lake Crescent, the δ15N of filamentous-periphytic algae growing in close proximity to the spawning areas of a unique species of trout show little evidence of elevated δ15N indicating that nitrogen from on-site septic systems is not a substantial source of nitrogen for these plants. The δ15N data corroborate estimates that nitrogen input to Lake Crescent from septic sources is comparatively small relative to input from motor vehicle exhaust and vegetative sources in undeveloped forests, including litterfall, pollen, and symbiotic nitrogen fixation. The seasonal timing of blooms of filamentous-periphytic algal near the lake shoreline is also consistent with nitrogen exported from stands of red alder trees (Alnus rubra). Isotope biomonitoring of filamentous-periphytic algae may be an effective approach to monitoring the littoral zone for nutrient input to Lake Crescent from septic sources.

Nitrogen balances at farm level as a tool to monitor effects of agri-environment policy

NARCIS (Netherlands)

Brouwer, F.M.

1998-01-01

Nitrogen balances at farm level are an important tool for monitoring the effects of agri-environmental policy in the European Union. Nitrogen surpluses, defined as the difference between input and output flows, are a pressure indicator to link agricultural activities with environmental quality

Neutron activation procedures used for the calibration of a nitrogen-16 reactor power monitor

International Nuclear Information System (INIS)

Jester, W.A.; Daubenspeck, T.

2000-01-01

Personnel from the Pennsylvania State University's Breazeale Nuclear Reactor assisted NRC (Nuclear Research Corporation) personnel in calibrating a new MSL/ 16 N Nitrogen-16 Monitor. Neutron flux calibration procedures utilized and the results obtained for the production of a nitrogen-16 source of known activity for a BGO detector calibration are described. (author)

Nitrogen Transformation and Removal in Horizontal Surface Flow ...

African Journals Online (AJOL)

The potential use of Constructed Mangrove Wetlands (CMWs) as a cheaper, effective and appropriate method for Nitrogen removal from domestic sewage of coastal zone in peri-urban cities was investigated from August 2007 to. September, 2008. Field investigations were made on horizontal surface flow constructed ...

Comparative Study of Water and Nitrogen Fertilizer Application on Potato Crop under Fertigation and Surface Irrigating Systems by Using Labeled Nitrogen (15N)

International Nuclear Information System (INIS)

Abdullah Haidara, H. M.; Amin Alkirshi, A. H.; Saleh Husien, A.

2007-01-01

This research activity was conducted at Central Highland Research Station Farm-Dhamar, on potato Crop (Diamant cv.), during three seasons of 2000, 2001, and 2003.The objective of this activity was to study the Nitrogen Fertilizer Use Efficiency (WUE) which applied in different dosages with irrigation water (fertigation) and one dosage to the soil under surface irrigation, by using Labeled nitrogen fertilizer ( 15N ), comparing the quantity of irrigation water applied through Drip irrigation method and surface irrigation and its effect on WUE and yield of potato crop. The basic experiment was planted in randomized completely block design (RCBD) with five replications during 2000 season and six replication in 2001.and five treatments were tested (N1= 50kg N/ha, N2 =100kg N/ha, N3=150kg N/ha and N4=200kgN/ha as fertigated treatments under drip irrigation and Ns = 150kg N/ha as surface Nitrogen Application under surface irrigation. While in the 2003 season Verification trial was conducted with two replications, two treatments and RCB design. Results indicated that using Drip irrigation method in application of water saved 38% of irrigation water as compared to Surface irrigation. Fertigated treatments (N1, N2, N3 and N4) were, significantly superior to Surface Nitrogen Application treatment (NS), fertigated treatment (N3) gave the highest values of WUE which were 5.3, 6.4 and 6.1 kg/m3 for the three seasons (2000, 2001, 2003 respectively) with an average of 5.9 kg/m3 comparing to the surface Nitrogen Application treatment (NS) which gave the less yield per unit of water which was 3.8, 3.6 and 3.9 kg /m3 for the three seasons 2000, 2001 and 2003 respectively with an average of 3.7 kg/m3.The Average yield of potato tubers for (N3) treatment in the three seasons was 30 .3 t/ha comparing to the (NS) treatment, which gave an average of 29,5t/ha.The fertigatetd treatment (N1) recorded the highest efficient use of nitrogen Fertilizer followed by (N3) compare to the surface

Monitoring of surface and airborne contamination

Energy Technology Data Exchange (ETDEWEB)

Pradeep Kumar, K S [Bhabha Atomic Research Centre, Bombay (India)

1997-06-01

Indian nuclear energy programme aims at total safety in all activities involved in the entire fuel cycle for the occupational workers, members of the public and the environment as a whole. Routine radiation monitoring with clearly laid out procedures are followed for ensuring the safety of workers and public. Radiation monitoring carried out for the nuclear installations comprises of process monitoring, monitoring of effluent releases and also of the radiation protection monitoring of the individuals, work place and environment. Regulations like banning of smoking and consumption of food and drink etc. reduces the risk of direct ingestion even if inadvertent spread of contamination takes place. Though limit of transportable surface contamination is prescribed, the health physicists always follow a ``clean on swipe`` philosophy which compensates any error in the measurement of surface contamination. In this paper, the following items are contained: Necessity of contamination monitoring, accuracy required in the calibration of surface contamination monitors, methodology for contamination monitoring, air monitoring, guidelines for unrestricted release of scrap materials, and problems in contamination monitoring. (G.K.)

Carbon Monoxide, Nitric Oxide, and Nitrogen Dioxide Levels in Gas Ovens Related to Surface Pinking of Cooked Beef and Turkey.

Science.gov (United States)

Cornforth; Rabovitser; Ahuja; Wagner; Hanson; Cummings; Chudnovsky

1998-01-19

Carbon monoxide (CO) and total nitrogen oxide (NO(x)()) levels were monitored during meat cookery with a standard Ovenpak and a new ultralow-NO(x)() (ULN) cyclonic gas burner. With the standard burner, CO varied from 103 to 152 ppm, NO(x)() was 1.3-10.7 ppm, and surface pinking was observed on both beef and turkey. The ULN burner at optimal efficiency produced only 6.7 ppm of CO and 1 ppm of NO(x)(), insufficient to cause surface pinking. To determine the relative contribution of CO and NO(x)() to pinking, trials were also conducted in an electric oven with various pure gases. Pinking was not observed with up to 149 ppm of CO or 5 ppm of NO. However, as little as 0.4 ppm of nitrogen dioxide (NO(2)) caused pinking of turkey rolls. Beef roasts were pink at >2.5 ppm of NO(2). Thus, pinking previously attributed to CO and NO in gas ovens is instead due to NO(2), which has much greater reactivity than NO with moisture at meat surfaces.

The characteristics of surface oxidation and corrosion resistance of nitrogen implanted zircaloy-4

International Nuclear Information System (INIS)

Tang, G.; Choi, B.H.; Kim, W.; Jung, K.S.; Kwon, H.S.; Lee, S.J.; Lee, J.H.; Song, T.Y.; Shon, D.H.; Han, J.G.

1997-01-01

This work is concerned with the development and application of ion implantation techniques for improving the corrosion resistance of zircaloy-4. The corrosion resistance in nitrogen implanted zircaloy-4 under a 120 keV nitrogen ion beam at an ion dose of 3 x 10 17 cm -2 depends on the implantation temperature. The characteristics of surface oxidation and corrosion resistance were analyzed with the change of implantation temperature. It is shown that as implantation temperature rises from 100 to 724 C, the colour of specimen surface changes from its original colour to light yellow at 100 C, golden at 175 C, pink at 300 C, blue at 440 C and dark blue at 550 C. As the implantation temperature goes above 640 C, the colour of surface changes to light black, and the surface becomes a little rough. The corrosion resistance of zircaloy-4 implanted with nitrogen is sensitive to the implantation temperature. The pitting potential of specimens increases from 176 to 900 mV (SCE) as the implantation temperature increases from 100 to 300 C, and decreases from 900 to 90 mV(SCE) as the implantation temperature increases from 300 to 640 C. The microstructure, the distribution of oxygen, nitrogen and carbon elements, the oxide grain size and the feature of the precipitation in the implanted surface were investigated by optical microscope, TEM, EDS, XRD and AES. The experimental results reveal that the ZrO 2 is distributed mainly on the outer surface. The ZrN is distributed under the ZrO 2 layer. The characteristics of the distribution of ZrO 2 and ZrN in the nitrogen-implanted zircaloy-4 is influenced by the implantation temperature of the sample, and in turn the corrosion resistance is influenced. (orig.)

Surface modification of polyacrylonitrile co-polymer membranes using pulsed direct current nitrogen plasma

Energy Technology Data Exchange (ETDEWEB)

Pal, Dipankar; Neogi, Sudarsan; De, Sirshendu, E-mail: sde@che.iitkgp.ernet.in

2015-12-31

Low temperature plasma treatment using pulsed direct current discharge of nitrogen gas was employed to enhance hydrophilicity of the polyacrylonitrile co-polymer membranes. The membranes were characterized in terms of morphology, structure, hydrophilicity, and membrane performance. Properties and functional groups on the surface of polyacrylonitrile co-polymer membranes were investigated by contact angle, scanning electron microscopy, Fourier transform infrared and X-ray photoelectron spectroscopy. Effects of plasma conditions, namely, pulsed voltage, duty cycle and treatment time on increase in membrane hydrophilicity were studied. Permeability of treated membrane was increased by 47% and it was retained up to 70 days. Surface etching due to plasma treatment was confirmed by weight loss of the treated membranes. Due to surface etching, average pore size increased and rejection of 200 kDa polyethylene glycol decreased to about 70% for the treated membrane. Oxygen and nitrogen functional groups were responsible for surface hydrophilicity. - Highlights: • Surface modification of polyacrylonitrile co-polymer membranes by pulsed direct current nitrogen plasma • Hydrophilic functional groups incorporated on the membrane surface • Significant enhancement of the permeability and wettability of the membranes • Water contact angle increased with storage time and finally stabilized.

Surface modification of polyacrylonitrile co-polymer membranes using pulsed direct current nitrogen plasma

International Nuclear Information System (INIS)

Pal, Dipankar; Neogi, Sudarsan; De, Sirshendu

2015-01-01

Low temperature plasma treatment using pulsed direct current discharge of nitrogen gas was employed to enhance hydrophilicity of the polyacrylonitrile co-polymer membranes. The membranes were characterized in terms of morphology, structure, hydrophilicity, and membrane performance. Properties and functional groups on the surface of polyacrylonitrile co-polymer membranes were investigated by contact angle, scanning electron microscopy, Fourier transform infrared and X-ray photoelectron spectroscopy. Effects of plasma conditions, namely, pulsed voltage, duty cycle and treatment time on increase in membrane hydrophilicity were studied. Permeability of treated membrane was increased by 47% and it was retained up to 70 days. Surface etching due to plasma treatment was confirmed by weight loss of the treated membranes. Due to surface etching, average pore size increased and rejection of 200 kDa polyethylene glycol decreased to about 70% for the treated membrane. Oxygen and nitrogen functional groups were responsible for surface hydrophilicity. - Highlights: • Surface modification of polyacrylonitrile co-polymer membranes by pulsed direct current nitrogen plasma • Hydrophilic functional groups incorporated on the membrane surface • Significant enhancement of the permeability and wettability of the membranes • Water contact angle increased with storage time and finally stabilized.

Nitrogen diffusion in near-surface range of ion doped molybdenum

CERN Document Server

Zamalin, E Y

2001-01-01

The dynamics of change in nitrogen near-the-surface concentration in the Mo ion-alloyed monocrystalline foil is studied through the Auger-electron spectroscopy and the secondary ion mass spectrometry. The implantation dose constituted 5 x 10 sup 1 sup 7 ion/cm sup 2 and the implantation energy equaled 50 and 100 keV. The samples diffusion annealing was performed at the temperature of 800-900 deg C. The evaluation of the nitrogen diffusion coefficient indicates the values by 3-5 orders lesser than the diffusion coefficient in the nitrogen solid-state solution in the molybdenum. At the same time the molybdenum self-diffusion coefficient value is by 3-5 orders lesser as compared to the obtained value. The supposition is made, the the surplus nitrogen relative to the solubility limit is deposited on the radiation defects and in the process of the diffusion annealing it nitrates together with them

E-PERM alpha surface monitor

International Nuclear Information System (INIS)

Fricke, V.

1999-01-01

Innovative Technology Summary Reports are designed to provide potential users with the information they need to quickly determine if a technology would apply to a particular environmental management problem. They are also designed for readers who may recommend that a technology be considered by prospective users. Each report describes a technology, system, or process that has been developed and tested with funding from DOE's Office of Science and Technology (OST). The E-PERMreg s ign Alpha Surface Monitor is an integrating electret ion chamber innovative technology used to measure alpha radiation on surfaces of materials. The technology is best used on surfaces with low contamination levels such as areas with potential for free release, but can also be used in areas with higher levels of contamination. Measurement accuracy and production of the E-PERM reg s ign Alpha Surface Monitor compared favorably with the baseline technology. The innovative technology cost is approximately 28% higher than the baseline with an average unit cost per reading costing %6.04 vs. $4.36; however, the flexibility of the E-PERMreg s ign Alpha Surface Monitor may offer advantages in ALARA, reduction of operator error, waste minimization, and measurement accuracy

Characterization of Nitride Layers Formed by Nitrogen Ion Implantation into Surface Region of Iron

International Nuclear Information System (INIS)

Sudjatmoko; Subki, M. Iyos R.

2000-01-01

Ion implantation is a convenient means of modifying the physical and chemical properties of the near-surface region of materials. The nitrogen implantation into pure iron has been performed at room temperature with ion dose of 1.310 17 to 1.310 18 ions/cm 2 and ion energy of 20 to 100 keV. The optimum dose of nitrogen ions implanted into pure iron was around 2.2310 17 ions/cm 2 in order to get the maximum wear resistant. SEM micrographs and EDX show that the nitride layers were found on the surface of substrate. The nitrogen concentration profile was measured using EDX in combination with spot technique, and it can be shown that the depth profile of nitrogen implanted into substrate was nearly Gaussian. (author)

First-principles study on the interaction of nitrogen atom with α–uranium: From surface adsorption to bulk diffusion

International Nuclear Information System (INIS)

Su, Qiulei; Deng, Huiqiu; Xiao, Shifang; Li, Xiaofan; Hu, Wangyu; Ao, Bingyun; Chen, Piheng

2014-01-01

Experimental studies of nitriding on uranium surfaces show that the modified layers provide considerable protection against air corrosion. The bimodal distribution of nitrogen is affected by both its implantation and diffusion, and the diffusion of nitrogen during implantation is also governed by vacancy trapping. In the present paper, nitrogen adsorption, absorption, diffusion, and vacancy trapping on the surface of and in the bulk of α–uranium are studied with a first-principles density functional theory approach and the climbing image nudged elastic band method. The calculated results indicate that, regardless of the nitrogen coverage, a nitrogen atom prefers to reside at the hollow1 site and octahedral (Oct) site on and below the surface, respectively. The lowest energy barriers for on-surface and penetration diffusion occur at a coverage of 1/2 monolayer. A nitrogen atom prefers to occupy the Oct site in bulk α–uranium. High energy barriers are observed during the diffusion between neighboring Oct sites. A vacancy can capture its nearby interstitial nitrogen atom with a low energy barrier, providing a significant attractive nitrogen-vacancy interaction at the trapping center site. This study provides a reference for understanding the nitriding process on uranium surfaces

Improved cell viability and hydroxyapatite growth on nitrogen ion-implanted surfaces

Science.gov (United States)

Shafique, Muhammad Ahsan; Murtaza, G.; Saadat, Shahzad; Uddin, Muhammad K. H.; Ahmad, Riaz

2017-08-01

Stainless steel 306 is implanted with various doses of nitrogen ions using a 2 MV pelletron accelerator for the improvement of its surface biomedical properties. Raman spectroscopy reveals incubation of hydroxyapatite (HA) on all the samples and it is found that the growth of incubated HA is greater in higher ion dose samples. SEM profiles depict uniform growth and greater spread of HA with higher ion implantation. Human oral fibroblast response is also found consistent with Raman spectroscopy and SEM results; the cell viability is found maximum in samples treated with the highest (more than 300%) dose. XRD profiles signified greater peak intensity of HA with ion implantation; a contact angle study revealed hydrophilic behavior of all the samples but the treated samples were found to be lesser hydrophilic compared to the control samples. Nitrogen implantation yields greater bioactivity, improved surface affinity for HA incubation and improved hardness of the surface.

Liquid nitrogen cryotherapy for surface eye disease (an AOS thesis).

Science.gov (United States)

Fraunfelder, Frederick Web

2008-01-01

To evaluate the effects of new treatments with liquid nitrogen cryotherapy on some external eye conditions. In this retrospective case study, 6 separate series from a single tertiary care referral center practice are described. Liquid nitrogen cryotherapy was used to treat conjunctival amyloidosis, primary pterygia, recurrent pterygia, advancing wavelike epitheliopathy (AWLE), superior limbic keratoconjunctivitis (SLK), and palpebral vernal keratoconjunctivitis (VKC). The main outcome measure was the resolution of the disease process after treatment. Four patients with primary localized conjunctival amyloidosis were treated with liquid nitrogen cryotherapy. Two of them had recurrence of the amyloidosis, which cleared with subsequent treatment. Eighteen patients with primary pterygia had excision and cryotherapy with 1 recurrence. Of 6 subjects who presented with recurrent pterygia, 4 had a second recurrence after excision and cryotherapy. In 5 patients with AWLE, the condition resolved within 2 weeks without recurrence or the need for subsequent cryotherapy. Four patients with SLK were treated with liquid nitrogen cryotherapy. Disease recurred in 2 patients and 3 of 7 eyes, although subsequent cryotherapy eradicated SLK in all cases. Two patients and 3 eyelids with palpebral VKC were treated with liquid nitrogen cryotherapy. VKC recurred in all cases. Liquid nitrogen cryotherapy to the surface of the eye is effective in treating AWLE, and SLK. Excision followed by cryotherapy is successful in treating conjunctival amyloidosis and primary pterygia Liquid nitrogen cryotherapy is unsuccessful in the treatment of recurrent pterygia and VKC.

Investigations of nitrogen oxide plasmas: Fundamental chemistry and surface reactivity and monitoring student perceptions in a general chemistry recitation

Science.gov (United States)

Blechle, Joshua M.

Part I of this dissertation focuses on investigations of nitrogen oxide plasma systems. With increasing concerns over the environmental presence of NxOy species, there is growing interest in utilizing plasma-assisted conversion techniques. Advances, however, have been limited because of the lack of knowledge regarding the fundamental chemistry of these plasma systems. Understanding the kinetics and thermodynamics of processes in these systems is vital to realizing their potential in a range of applications. Unraveling the complex chemical nature of these systems, however, presents numerous challenges. As such, this work serves as a foundational step in the diagnostics and assessment of these NxOy plasmas. The partitioning of energy within the plasma system is essential to unraveling these complications as it provides insight into both gas and surface reactivity. To obtain this information, techniques such as optical emission spectroscopy (OES), broadband absorption spectroscopy (BAS), and laser induced fluorescence (LIF) were utilized to determine species energetics (vibrational, rotational, translational temperatures). These temperature data provide mechanistic insight and establish the relationships between system parameters and energetic outcomes. Additionally, these data are also correlated to surface reactivity data collected with the Imaging of Radicals Interacting with Surfaces (IRIS) technique. IRIS data demonstrate the relationship between internal temperatures of radicals and their observed surface scatter coefficients (S), the latter of which is directly related to surface reactivity (R) [R = 1-S]. Furthermore, time-resolved (TR) spectroscopic techniques, specifically TR-OES, revealed kinetic trends in NO and N2 formation from a range of precursors (NO, N2O, N2/O2). By examining the rate constants associated with the generation and destruction of various plasma species we can investigate possible mechanistic implications. All told, such data provides

Nitrogen isotope ratios in surface and sub-surface soil horizons

International Nuclear Information System (INIS)

Rennie, D.A.; Paul, E.A.

1975-01-01

Nitrogen isotope analysis of surface soils and soil-derived nitrate for selected chernozemic and luvisolic soils showed mean delta 15 N values of 11.7 and 11.3, respectively. Isotope enrichment of the total N reached a maximum in the lower B horizon. Sub-soil parent material samples from the one deep profile included in the study indicated a delta 15 N value (NO 3 -N) of 1/3 that of the Ap horizon, at a depth of 180 cm. The delta 15 N of sub-surface soil horizons containing residual fertilizer N were low (-2.2) compared to the surface horizon (9.9). The data reported from this preliminary survey suggest that the natural variations in 15 N abundance between different soils and horizons of the same soil reflect the cumulative effects of soil genesis and soil management. More detailed knowledge and understanding of biological and other processes which control N isotope concentrations in these soils must be obtained before the data reported can be interpreted. (author)

Urban rivers as hotspots of regional nitrogen pollution

International Nuclear Information System (INIS)

Zhang, Xiaohong; Wu, Yiyun; Gu, Baojing

2015-01-01

Excess nitrogen inputs to terrestrial ecosystems via human activities have deteriorated water qualities on regional scales. Urban areas as settlements of over half global population, however, were usually not considered in the analysis of regional water pollution. Here, we used a 72-month monitoring data of water qualities in Hangzhou, China to test the role of urban rives in regional nitrogen pollution and how they response to the changes of human activities. Concentrations of ammonium nitrogen in urban rivers were 3–5 times higher than that in regional rivers. Urban rivers have become pools of reactive nitrogen and hotspots of regional pollution. Moreover, this river pollution is not being measured by current surface water monitoring networks that are designed to measure broader regional patterns, resulting in an underestimation of regional pollution. This is crucial to urban environment not only in China, but also in other countries, where urban rivers are seriously polluted. - Highlights: • Nitrogen concentrations in urban rivers are much higher than that in regional rivers. • Domestic wastewater is the main source of urban river pollution in Hangzhou. • Pollutant collecting and water diversion can sharply reduce the urban river pollution. - Urban river pollution is not being measured by the current monitoring networks that are designed to measure regional patterns causing an underestimation

Modelling of long term nitrogen retention in surface waters

Science.gov (United States)

Halbfaß, S.; Gebel, M.; Bürger, S.

2010-12-01

In order to derive measures to reduce nutrient loadings into waters in Saxony, we calculated nitrogen inputs with the model STOFFBILANZ on the regional scale. Thereby we have to compare our modelling results to measured loadings at the river basin outlets, considering long term nutrient retention in surface waters. The most important mechanism of nitrogen retention is the denitrification in the contact zone of water and sediment, being controlled by hydraulic and micro-biological processes. Retention capacity is derived on the basis of the nutrient spiralling concept, using water residence time (hydraulic aspect) and time-specific N-uptake by microorganisms (biological aspect). Short time related processes of mobilization and immobilization are neglected, because they are of minor importance for the derivation of measures on the regional scale.

First-principles simulations of iron with nitrogen: from surface adsorption to bulk diffusion

International Nuclear Information System (INIS)

Wu, M H; Liu, X H; Gu, J F; Jin, Z H

2013-01-01

Adsorption, absorption and diffusion pathways of nitrogen are studied for ferromagnetic body-centered cubic iron via spin-polarized density functional theory in combination with the climbing image nudged elastic band method. The computed data suggest that, depending on the coverage of N atoms, N prefers to stay on particular surface sites. Once pinned down well below the surface, N prefers to move into octahedral interstices rather than tetrahedral interstices. However, the tetrahedral interstices are crucial because they act as transition states and yield the saddle point energies of the corresponding minimum energy pathways. In comparison with carbon, we found that nitrogen prefers a different pathway from the (1 0 0) surface to the subsurface due to its strong repulsive interaction with Fe ions. (paper)

Time-resolved investigation of the surface chemical modification of poly(ethylene naphthalate) by nitrogen plasma treatment

International Nuclear Information System (INIS)

Grace, J.M.; Zhuang, H.K.; Gerenser, L.J.; Freeman, D.R.

2003-01-01

A low rf nitrogen plasma source was used to treat poly(ethylene-2, 6-naphthalate) web material. Nitrogen uptake, the N 1s centroid, the N 1s peak width, rearrangement of the ester (from the O 1s spectrum), and oxygen level were measured using x-ray photoelectron spectroscopy as a function of treatment time at several treatment conditions. The observed changes in surface chemistry with treatment time are roughly consistent with a dose response having a linear regime at low doses and a saturation regime at high doses (where dose is power/width/web speed). Hence, to a first approximation, the flux densities (to the web) of relevant species scale with power. As the dose increases, the distribution of nitrogen groups formed broadens and shifts toward higher N 1s binding energy, suggesting that a larger fraction of the nitrogen-containing species are amines at low doses and amides at higher doses. The breadth of the distribution of nitrogen-containing species appears to be strongly correlated with the amount of nitrogen incorporated in the PEN surface. A surface sites model was applied to the measured nitrogen uptake as a function of treatment time. Phenomenological nitrogen incorporation and loss terms were determined in the context of this model. Both terms increase with treatment power and treatment pressure. The ratio, however, varies to a much smaller degree as a function of process conditions, with high powers and pressures giving the highest ratio. Further elucidation of the incorporation and loss processes should be possible with plasma diagnostic data related to species concentrations

Near-surface microstructural modification of (Ti,W)(C,N)-based compacts with nitrogen

International Nuclear Information System (INIS)

Ucakar, V.; Kral, C.; Lengauer, W.

2001-01-01

For developing of functional-gradient hardmetals the interaction of nitrogen with (Ti,W)(C,N)-based compacts was investigated. Hot-pressed (Ti,W)(C,N) compacts as well as sintered compacts of (Ti,W)(C,N)+Co were subjected to sintering and heat treatment at 1200-1500 o C and up to 30 bar N 2 . In (Ti,W)(C,N) compacts four microstructure types were obtained upon reaction with nitrogen. A uniform single-phase (Ti,W)(C,N) forms in samples with a low WC and high TiN content. If medium WC and high TiN/TiC ratio is present a core-rim type structure forms during Ar annealing which remains the same when nitrogen in-diffusion occurs. The third type of microstructure shows sub-micron lamellae of nitrogen-rich fcc phase and WC. This structure forms at increased WC and/or TiC content. If the WC content is increased again a WC layer forms at the outermost surface. Compressive stresses introduced by phase formation/decomposition were obtained for the nitrogen in-diffusion. Sintered (Ti,W)(C,N)+Co compacts were heat treated above and below the eutectic temperature. Above the eutectic temperature compact Ti(C,N) top-layers independent an sample composition were observed. Below the eutectic temperature the microstructure formation is mainly influenced by the sample composition. A Ti(C,N) top-layer forms in materials with a high Ti(C,N) content. Contrary, interaction zones without a layer were obtained in compacts with high WC/Ti(C,N) ratio. Some of these surface modified compacts show surfaces and particle sizes favorable for a cutting tool. (author)

Surface Quality Improvement of AA6060 Aluminum Extruded Components through Liquid Nitrogen Mold Cooling

Directory of Open Access Journals (Sweden)

Andrea Francesco Ciuffini

2018-06-01

Full Text Available 6xxx aluminum alloys are suitable for the realization of both structural applications and architectural decorative elements, thanks to the combination of high corrosion resistance and good surface finish. In areas where the aesthetic aspects are fundamental, further improvements in surface quality are significant. The cooling of the extrusion mold via internal liquid nitrogen fluxes is emerging as an important innovation in aluminum extrusion. Nowadays, this innovation is providing a large-scale solution to obtain high quality surface finishes in extruded aluminum semi-finished products. These results are also coupled to a significant increase in productivity. The aim of the work is to compare the surface quality of both cooled liquid nitrogen molds and classically extruded products. In this work, adhesion phenomena, occurring during the extrusion between the mold and the flowing material, have been detected as the main causes of the presence of surface defects. The analysis also highlighted a strong increase in the surface quality whenever the extrusion mold was cooled with liquid nitrogen fluxes. This improvement has further been confirmed by an analysis performed on the finished products, after painting and chromium plating. This work on the AA6060 alloy has moreover proceeded to roughness measurements and metallographic analyses, to investigate the eventual occurrence of other possible benefits stemming from this new extrusion mold cooling technology.

Surface and morphological features of laser-irradiated silicon under vacuum, nitrogen and ethanol

Energy Technology Data Exchange (ETDEWEB)

Hayat, Asma, E-mail: asmahayat@gcu.edu.pk; Bashir, Shazia; Akram, Mahreen; Mahmood, Khaliq; Iqbal, Muhammad Hassan

2015-12-01

Highlights: • Laser irradiation effects on Si surface have been explored. • An Excimer Laser was used as a source. • SEM analysis was performed to explore surface morphology. • Raman spectroscopy analysis was carried out to find crystallographical alterations. - Abstract: Laser-induced surface and structural modification of silicon (Si) has been investigated under three different environments of vacuum, nitrogen (100 Torr) and ethanol. The interaction of 1000 pulses of KrF (λ ≈ 248 nm, τ ≈ 18 ns, repetition rate ≈ 30 Hz) Excimer laser at two different fluences of 2.8 J/cm{sup 2} and 4 J/cm{sup 2} resulted in formation of various kinds of features such as laser induced periodic surface structures (LIPSS), spikes, columns, cones and cracks. Surface morphology has been observed by Scanning Electron Microscope (SEM). Whereas, structural modification of irradiated targets is explored by Raman spectroscopy. SEM analysis exhibits a non-uniform distribution of micro-scale pillars and spikes at the central ablated regime of silicon irradiated at low laser fluence of 2.8 J/cm{sup 2} under vacuum. Whereas cones, pits, cavities and ripples like features are seen at the boundaries. At higher fluence of 4 J/cm{sup 2}, laser induced periodic structures as well as micro-columns are observed. In the case of ablation in nitrogen environment, melting, splashing, self-organized granular structures and cracks along with redeposition are observed at lower fluence. Such types of small scaled structures in nitrogen are attributed to confinement and shielding effects of nitrogen plasma. Whereas, a crater with multiple ablative layers is formed in the case of ablation at higher fluence. Significantly different surface morphology of Si is observed in the case of ablation in ethanol. It reveals the formation of cavities along with small scale pores and less redeposition. These results reveal that the growth of surface and morphological features of irradiated Si are strongly

Surface and morphological features of laser-irradiated silicon under vacuum, nitrogen and ethanol

International Nuclear Information System (INIS)

Hayat, Asma; Bashir, Shazia; Akram, Mahreen; Mahmood, Khaliq; Iqbal, Muhammad Hassan

2015-01-01

Highlights: • Laser irradiation effects on Si surface have been explored. • An Excimer Laser was used as a source. • SEM analysis was performed to explore surface morphology. • Raman spectroscopy analysis was carried out to find crystallographical alterations. - Abstract: Laser-induced surface and structural modification of silicon (Si) has been investigated under three different environments of vacuum, nitrogen (100 Torr) and ethanol. The interaction of 1000 pulses of KrF (λ ≈ 248 nm, τ ≈ 18 ns, repetition rate ≈ 30 Hz) Excimer laser at two different fluences of 2.8 J/cm 2 and 4 J/cm 2 resulted in formation of various kinds of features such as laser induced periodic surface structures (LIPSS), spikes, columns, cones and cracks. Surface morphology has been observed by Scanning Electron Microscope (SEM). Whereas, structural modification of irradiated targets is explored by Raman spectroscopy. SEM analysis exhibits a non-uniform distribution of micro-scale pillars and spikes at the central ablated regime of silicon irradiated at low laser fluence of 2.8 J/cm 2 under vacuum. Whereas cones, pits, cavities and ripples like features are seen at the boundaries. At higher fluence of 4 J/cm 2 , laser induced periodic structures as well as micro-columns are observed. In the case of ablation in nitrogen environment, melting, splashing, self-organized granular structures and cracks along with redeposition are observed at lower fluence. Such types of small scaled structures in nitrogen are attributed to confinement and shielding effects of nitrogen plasma. Whereas, a crater with multiple ablative layers is formed in the case of ablation at higher fluence. Significantly different surface morphology of Si is observed in the case of ablation in ethanol. It reveals the formation of cavities along with small scale pores and less redeposition. These results reveal that the growth of surface and morphological features of irradiated Si are strongly dependent upon the

A first principle simulation of competitive adsorption of SF6 decomposition components on nitrogen-doped anatase TiO2 (101) surface

Science.gov (United States)

Dong, Xingchen; Zhang, Xiaoxing; Cui, Hao; Zhang, Jun

2017-11-01

Gas insulated switchgear has been widely used in modern electric systems due to its significantly excellent performances such as compact structure and low land occupation as well as the security stability. However, inside defects caused during manufacture process can lead to partial discharge which might develop into serious insulation failure. Online monitoring method on basis of gas sensors is considered a promising way of detecting partial discharge for alarm ahead of time. Research has found that TiO2 nanotubes sensors show good response to SO2, SOF2, SO2F2, the decomposition components as a result of partial discharge. In order to investigate the gas-sensing mechanism of nitrogen-doped TiO2 prepared via plasma treatment methods to SO2, SOF2, and SO2F2, the adsorption structures of both three gas molecules and anatase TiO2 (101) surface were built, and DFT calculations were then carried out for calculation and analysis of adsorption parameters. Adsorption property comparison of anatase TiO2 (101) surface after nitrogen doping with Au doping and without doping shows that nitrogen doping can obviously enhance the adsorption energy for SO2 and SOF2 adsorption and no charge transfer for SO2F2 adsorption, further explaining the adsorption mechanism and doping influence of different doping elements.

Short-term diffusive sampler for nitrogen dioxide monitoring in epidemiology

International Nuclear Information System (INIS)

Michaud, J.P.; Quackenboss, J.

1991-01-01

An automated timed exposure diffusive sampler (TEDS) for sampling nitrogen dioxide (NO 2 ) was developed for use in epidemiological studies. The TEDS sequentially exposes four passive sampling devices (PSD) by microprocessor controlled valves while a pump and air flow guide prevent sampler starvation. Two TEDS units and two portable, real-time NO 2 monitors were tested for accuracy, precision, sensitivity, and linearity of response. The accuracy of the TEDS was within 10 percent of the means of the measured values. The TEDS sensitivity was 20 to 30 ppb-hour for NO 2 . Co-location of the TEDS with a chemiluminescent NO x monitor (EPA reference method) showed a similar responses to ambient NO 2 . TEDS allows better time resolution than traditional diffusive samplers (i.e., Palmes tube) while sharing their ability to sample a variety of gases

Statistical Analysis of Nitrogen in the Soil of Constructed Wetland with Horizontal Sub-Surface Flow

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Jakubaszek Anita

2014-06-01

Full Text Available The removal of nitrogen compounds in constructed wetlands depends on various physical, chemical and biomechanical factors as well as on conditions of the environment. The paper presents the results of a statistical analysis of the depositing of nitrogen at HSSF (horizontal subsurface flow construcred wetland. The results of the substrate showed that the highest contents of nitrogen existed in the surface soil layer up to 20 cm of the depth. Nitrogen accumulation decreased in the deposit with depth, and in the direction of the wastewater flow.

Effects of low-pressure nitrogen plasma treatment on the surface properties and electrochemical performance of the polyethylene separator used lithium-ion batteries

Science.gov (United States)

Li, Chun; Li, Hsiao-Ling; Li, Chi-Heng; Liu, Yu-Shuan; Sung, Yu-Ching; Huang, Chun

2018-01-01

In this paper, we describe the surface transition of the polyethylene (PE) separator used in lithium-ion batteries treated by low-pressure nitrogen plasma discharge. The nitrogen-plasma-treated PE separator was characterized by contact angle measurement, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy. The electrochemical performance of the lithium ion batteries fabricated with the nitrogen-plasma-treated separator was also evaluated. Results showed that polar functionalization groups were induced on the PE surface by the nitrogen plasma discharge, causing the surface to become hydrophilic. The increases in surface wettability and surface free energy result in electrolyte retention improvement. Moreover, the nitrogen plasma-treated PE separator leads to superior performance in lithium-ion battery assembly.

Decadal changes in global surface NO

NARCIS (Netherlands)

Miyazaki, Kazuyuki; Eskes, Henk; Sudo, Kengo; Boersma, Folkert; Bowman, Kevin; Kanaya, Yugo

2017-01-01

Global surface emissions of nitrogen oxides (NO_x ) over a 10-year period (2005-2014) are estimated from an assimilation of multiple satellite data sets: tropospheric NO₂ columns from Ozone Monitoring Instrument (OMI), Global Ozone Monitoring Experiment-2 (GOME- 2), and

Modeling nitrogen fluxes in Germany - where does the nitrogen go?

Science.gov (United States)

Klement, Laura; Bach, Martin; Breuer, Lutz

2016-04-01

According to the latest inventory of the EU Water Framework Directive, 26.3% of German groundwater bodies are in a poor chemical state regarding nitrate. Additionally, the EU initiated infringement proceedings against Germany for not meeting the quality standards of the EU Nitrate Directive. Agriculture has been determined as the main source of nitrate pollution due to over-fertilization and regionally high density of livestock farming. The nitrogen balance surplus is commonly used as an indicator characterizing the potential of nitrate leaching into groundwater bodies and thus also serves as a foundation to introduce legislative restrictions or to monitor the success of mitigation measures. Currently, there is an ongoing discussion which measures are suitable for reducing the risk of nitrate leaching and also to what extent. However, there is still uncertainty about just how much the nitrogen surplus has to be reduced to meet the groundwater quality standards nationwide. Therefore, the aims of our study were firstly to determine the level of the nitrogen surplus that would be acceptable at the utmost and secondly whether the currently discussed target value of 30 kg N per hectare agricultural land for the soil surface nitrogen balance would be sufficient. The models MONERIS (Modeling Nutrient Emissions in River System) and MoRE (Modelling of Regionalized Emissions), the latter based on the first, are commonly used for estimating nitrogen loads into the river system in Germany at the mesoscale, as well as the effect of mitigation measures in the context of the EU directive 2008/105/EC (Environmental quality standards applicable to surface water). We used MoRE to calculate nitrate concentration for 2759 analytical units in Germany. Main factors are the surplus of the soil surface nitrogen balance, the percolation rate and an exponent representing the denitrification in the vadose zone. The modeled groundwater nitrate concentrations did not correspond to the regional

Investigation of fluorine adsorption on nitrogen doped MgAl_2O_4 surface by first-principles

International Nuclear Information System (INIS)

Lv, Xiaojun; Xu, Zhenming; Li, Jie; Chen, Jiangan; Liu, Qingsheng

2016-01-01

Graphical abstract: First-principles calculations indicate that MgAl_2O_4 surface is fluorine-loving, but hydrophobic. N doped MgAl_2O_4 (100) surface structure shows the highest fluorine adsorption performance and fluorine atom is more preferentially adsorbed on the Mg-Al bridge site. The fluorine adsorption intensity follow this order: N doped MgAl_2O_4 (100) > Al_2O_3 (0001) > MgAl_2O_4 (100) > MgO (100). N doped MgAl_2O_4 is a promising candidate for fluorine removal. - Highlights: • MgAl_2O_4 surface is fluorine-loving, not hydrophilic. • Fluorine preferentially adsorbs on the Mg-Al bridge site. • Adsorption intensity follow this order: N doped MgAl_2O_4 > Al_2O_3 > MgAl_2O_4 > MgO. • Excellent adsorption performance attributes to electron compensation of N atom. • Nitrogen doped MgAl_2O_4 is a promising candidate for fluorine removal. - Abstract: The nature of fluorine adsorption on pure and N doped MgAl_2O_4 surface has been investigated by first-principles calculations based on the density functional theory. Calculated results indicate that MgAl_2O_4 surface is fluorine-loving, not hydrophilic. Nitrogen doped MgAl_2O_4 (100) surface shows the highest fluorine adsorption performance and fluorine atom preferentially adsorbs on the Mg-Al bridge site. The fluorine adsorption intensity follow this order: Nitrogen doped MgAl_2O_4 (100) > Al_2O_3 (0001) > MgAl_2O_4 (100) > MgO (100). In-depth PDOS analysis suggested that 2p orbitals of F atom strongly hybridized with 3s- and 3p-orbitals of Al atom contribute to its high adsorption intensity. According to the analysis of Hirshfeld charge, the excellent fluorine adsorption performance of nitrogen doped MgAl_2O_4 attributes to the electron compensation effect of nitrogen atom and strong electrostatic interactions. All these evidences demonstrate a fact nitrogen doped MgAl_2O_4 is a promising candidate for fluorine removal.

Incorporation of low energy activated nitrogen onto HOPG surface: Chemical states and thermal stability studies by in-situ XPS and Raman spectroscopy

Science.gov (United States)

Chandran, Maneesh; Shasha, Michal; Michaelson, Shaul; Hoffman, Alon

2016-09-01

In this paper we report the chemical states analysis of activated nitrogen incorporated highly oriented pyrolytic graphite (HOPG) surface under well-controlled conditions. Nitrogen incorporation is carried out by two different processes: an indirect RF nitrogen plasma and low energy (1 keV) N2+ implantation. Bonding configuration, concentration and thermal stability of the incorporated nitrogen species by aforesaid processes are systematically compared by in-situ X-ray photoelectron spectroscopy (XPS). Relatively large concentration of nitrogen is incorporated onto RF nitride HOPG surface (16.2 at.%), compared to N2+ implanted HOPG surface (7.7 at.%). The evolution of N 1s components (N1, N2, N3) with annealing temperature is comprehensively discussed, which indicates that the formation and reorganization of local chemical bonding states are determined by the process of nitridation and not by the prior chemical conditioning (i.e., amorphization or hydrogenation) of the HOPG surface. A combined XPS and Raman spectroscopy studies revealed that N2+ implantation process resulted in a high level of defects to the HOPG surface, which cannot be annealed-out by heat treatment up to 1000 °C. On the other hand, the RF nitrogen plasma process did not produce a high level of surface defects, while incorporating nearly the same amount of stable nitrogen species.

Changes of surface layer of nitrogen-implanted AISI316L stainless steel

International Nuclear Information System (INIS)

Budzynski, P.; Polanski, K.; Kobzev, A.P.

2007-01-01

The effects of nitrogen ion implantation into AISI316L stainless steel on friction, wear, and microhardness have been investigated at an energy level of 125 keV at a fluence of 1·10 17 - 1·10 18 N/cm 2 . The composition of the surface layer was investigated by RBS, XRD (GXRD), SEM and EDX. The friction coefficient and abrasive wear rate of the stainless steel were measured in the atmospheres of air, oxygen, argon, and in vacuum. As follows from the investigations, there is an increase in resistance to frictional wear in the studied samples after implantation; however, these changes are of different characters in various atmospheres. The largest decrease in wear was observed during tests in the air, and the largest reduction in the value of the friction coefficient for all implanted samples was obtained during tests in the argon atmosphere. Tribological tests revealed larger contents of nitrogen, carbon, and oxygen in the products of surface layer wear than in the surface layer itself of the sample directly after implantation

Adsorption of nitrogen on W(100): effect of surface disorder on the work function change

International Nuclear Information System (INIS)

Singh-Bofarai, S.P.; King, D.A.

1976-01-01

At room temperature nitrogen adsorption causes the work function of the (100) plane of tungsten to decrease by approximately 0.6 eV, while on all other planes the work function is increased, albeit by as little as 0.03 eV on the (110) plane. Surface disorder can readily be created by the vapour deposition of W onto a clean, annealed W single crystal surface, and in the present work this technique was used to shadow a W field emission tip with disordered W atoms so as to observe the effect of surface disorder on the work function change due to nitrogen adsorption, particularly at the (100) poles of the tip. (Auth.)

Nitrogen implantation of type 303 stainless steel gears for improved wear and fatigue resistance

International Nuclear Information System (INIS)

Kustas, F.M.; Misra, M.S.; Tack, W.T.

1987-01-01

Fine-positioning mechanisms are responsible for accurate and reproducible control of aerospace system devices, i.e. filter grading wheels. Low wear and fatigue resistance of mechanism components, such as pinions and gears, can reduce system performance and reliability. Surface modification using ion implantation with nitrogen was used on type 303 stainless steel pinions and gears to increase tribological performance. Wear-life tests of untreated, nitrogen-implanted and nitrogen-implanted-and-annealed gears were performed in a fine-positioning mechanism under controlled environmental conditions. Wear and fatigue resistance were monitored at selected time intervals which were a percentage of the predicted failure life as determined by a numerical stress analysis. Surface analyses including scanning electron microscopy and Auger electron spectroscopy were performed to establish the wear and fatigue mechanisms and the nitrogen concentration-depth distributions respectively. Nitrogen implantation resulted in a significant improvement in both surface wear and fatigue spalling resistance over those of untreated gears. A 40% reduction in surface wear and a 44% reduction in dedendum spalling was observed. In contrast, the nitrogen-implanted-and-annealed gears showed a 46% increase in sliding wear area and an 11% increase in spall density compared with those of untreated gears, indicating that the post-implantation anneal was detrimental to wear and fatigue resistance. (orig.)

Nitrogen-doped graphene network supported copper nanoparticles encapsulated with graphene shells for surface-enhanced Raman scattering

Science.gov (United States)

Zhang, Xiang; Shi, Chunsheng; Liu, Enzuo; Li, Jiajun; Zhao, Naiqin; He, Chunnian

2015-10-01

In this study, we demonstrated nitrogen-doped graphene network supported few-layered graphene shell encapsulated Cu nanoparticles (NPs) (Cu@G-NGNs) as a sensing platform, which were constructed by a simple and scalable in situ chemical vapor deposition (CVD) technique with the assistance of a self-assembled three-dimensional (3D) NaCl template. Compared with pure Cu NPs and graphene decorated Cu NPs, the graphene shells can strengthen the plasmonic coupling between graphene and Cu, thereby contributing to an obvious improvement in the local electromagnetic field that was validated by finite element numerical simulations, while the 3D nitrogen-doped graphene walls with a large surface area facilitated molecule adsorption and the doped nitrogen atoms embedded in the graphene lattice can reduce the surface energy of the system. With these merits, a good surface enhanced Raman spectroscopy (SERS) activity of the 3D Cu@G-NGN painting film on glass was demonstrated using rhodamine 6G and crystal violet as model analytes, exhibiting a satisfactory sensitivity, reproducibility and stability. As far as we know, this is the first report on the in situ synthesis of nitrogen-doped graphene/copper nanocomposites and this facile and low-cost Cu-based strategy tends to be a good supplement to Ag and Au based substrates for SERS applications.In this study, we demonstrated nitrogen-doped graphene network supported few-layered graphene shell encapsulated Cu nanoparticles (NPs) (Cu@G-NGNs) as a sensing platform, which were constructed by a simple and scalable in situ chemical vapor deposition (CVD) technique with the assistance of a self-assembled three-dimensional (3D) NaCl template. Compared with pure Cu NPs and graphene decorated Cu NPs, the graphene shells can strengthen the plasmonic coupling between graphene and Cu, thereby contributing to an obvious improvement in the local electromagnetic field that was validated by finite element numerical simulations, while the 3D nitrogen

Application of Response Surface Methodology for Optimization of Urea Grafted Multiwalled Carbon Nanotubes in Enhancing Nitrogen Use Efficiency and Nitrogen Uptake by Paddy Plants

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Norazlina Mohamad Yatim

2016-01-01

Full Text Available Efficient use of urea fertilizer (UF as important nitrogen (N source in the world’s rice production has been a concern. Carbon-based materials developed to improve UF performance still represent a great challenge to be formulated for plant nutrition. Advanced N nanocarrier is developed based on functionalized multiwall carbon nanotubes (f-MWCNTs grafted with UF to produce urea-multiwall carbon nanotubes (UF-MWCNTs for enhancing the nitrogen uptake (NU and use efficiency (NUE. The grafted N can be absorbed and utilized by rice efficiently to overcome the N loss from soil-plant systems. The individual and interaction effect between the specified factors of f-MWCNTs amount (0.10–0.60 wt% and functionalization reflux time (12–24 hrs with the corresponding responses (NUE, NU were structured via the Response Surface Methodology (RSM based on five-level CCD. The UF-MWCNTs with optimized 0.5 wt% f-MWCNTs treated at 21 hrs reflux time achieve tremendous NUE up to 96% and NU at 1180 mg/pot. Significant model terms (p value < 0.05 for NUE and NU responses were confirmed by the ANOVA. Homogeneous dispersion of UF-MWCNTs was observed via FESEM and TEM. The chemical changes were monitored by FT-IR and Raman spectroscopy. Hence, this UF-MWCNTs’ approach provides a promising strategy in enhancing plant nutrition for rice.

Application of a Chemiluminescence Detector for the Measurement of Total Oxides of Nitrogen and Ammonia in the Atmosphere

Science.gov (United States)

Hodgeson, J. A.; Bell, J. P.; Rehme, K. A.; Krost, K. J.; Stevens, R. K.

1971-01-01

By means of the thermal conversion of nitrogen dioxide to the nitric oxide, the chemiluminescent nitric oxide monitor, based on the nitric oxide plus ozone reaction, may be used for monitoring nitrogen dioxide plus nitric oxide (NO(x)). Under conditions previously described, ammonia is also converted to nitric oxide and therefore interferes. A metal surface, gold wool or stainless steel, operated at two different temperatures has been used to convert only nitrogen dioxide or nitrogen dioxide plus ammonia. Quantitative conversion of nitrogen dioxide to nitric oxide has been obtained at temperatures as low as 200 C. Conversion of ammonia is effected at temperatures of 300 C or higher. By the addition of a converter the basic nitric oxide monitor may be used for measuring NO(x) or NO(x) plus ammonia. As an alternate mode, for a fixed high temperature, a specific scrubber is described for removing NH3 without affecting NO2 concentrations.

Aluminum surface modification by a non-mass-analyzed nitrogen ion beam

Science.gov (United States)

Ohira, Shigeo; Iwaki, Masaya

Non-mass-analyzed nitrogen ion implantation into polycrystal and single crystal aluminum sheets has been carried out at an accelerating voltage of 90 kV and a dose of 1 × 10 18 N ions/cm 2 using a Zymet implanter model Z-100. The pressure during implantation rose to 10 -3 Pa due to the influence of N gas feeding into the ion source. The characteristics of the surface layers were investigated by means of Auger electron spectroscopy (AES), X-ray diffraction (XRD), transmission electron diffraction (TED), and microscopy (TEM). The AES depth profiling shows a rectangular-like distribution of N atoms and little migration of O atoms near the surface. The high dose N-implantation forms c-axis oriented aluminum nitride (AIN) crystallines, and especially irradiation of Al single crystals with N ions leads to the formation of a hcp AlN single crystal. It is concluded that the high dose N-implantation in Al can result in the formation of AlN at room temperature without any thermal annealing. Furthermore, non-mass-analyzed N-implantation at a pressure of 10 -3 Pa of the nitrogen atmosphere causes the formation of pure AlN single crystals in the Al surface layer and consequently it can be practically used for AlN production.

Detection of the ODMR signal of a nitrogen vacancy centre in nanodiamond in propagating surface plasmons

Science.gov (United States)

Al-Baiaty, Zahraa; Cumming, Benjamin P.; Gan, Xiaosong; Gu, Min

2018-02-01

We demonstrate that the optically detected magnetic resonance (ODMR) signal of a nitrogen vacancy (NV) centre can be coupled to propagating surface plasmons for the detection of the NV centre spin states, and of external magnetic fields. By coupling the spin dependent luminescence signal of a NV centre in a nanodiamond (ND) to a chemically synthesized silver nanowire, we demonstrate the readout of the ODMR signal as a reduction in the surface plasmon polariton intensity, with improved contrast in comparison to the emission from the NV centre. Furthermore, on the application of a permanent magnetic field from zero to 13 G, we demonstrate that the Zeeman splitting of the magnetic spin states of the nitrogen vacancy centre ground states can also be detected in the coupled surface plasmons. This is an important step in the development of a compact on-chip information processing system utilizing the nitrogen vacancy in nanodiamond as an on-chip source with efficient magnetometry sensing properties.

Effect of Saturated Near Surface on Nitrate and Ammonia Nitrogen Losses in Surface Runoff at the Loess Soil Hillslope

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Yu-bin Zhang

2010-01-01

Full Text Available Water pollution from agricultural fields is a global problem and cause of eutrophication of surface waters. A laboratory study was designed to evaluate the effects of near-surface hydraulic gradients on NO3–N and NH4–N losses in surface runoff from soil boxes at 27% slope undersimulated rainfall of a loess soil hillslope. Experimental treatments included two near-surface hydraulic gradients (free drainage, FD; saturation, SA, three fertilizer application rates (control, no fertilizer input; low, 120 kg N ha-1; high, 240 kg N ha-1, and simulated rainfall of 100 mm h-1 was applied for 70 min. The results showed that saturated near-surface soil moisture had dramatic effects on NO3–N and NH4–N losses and water quality. Under the low fertilizer treatment, average NO3–N concentrations in runoff water of SA averaged 2.2 times greater than that of FD, 1.6 times greater for NH4–N. Under the high fertilizer treatment, NO3–N concentrations in runoff water from SA averaged 5.7 times greater than that of FD, 4.3 times greater for NH4–N. Nitrogen loss formed with NO3–N is dominant during the event, but not NH4–N. Under the SA condition, the total loss of NO3–N from low fertilizer treatment was 34.2 to 42.3% of applied nitrogen, while under the FD treatment that was 3.9 to 6.9%. However, the total loss of NH4–N was less than 1% of applied nitrogen. These results showed that saturated condition could make significant contribution to water quality problems.

Solvent-induced synthesis of nitrogen-doped hollow carbon spheres with tunable surface morphology for supercapacitors

Science.gov (United States)

Liu, Feng; Yuan, Ren-Lu; Zhang, Ning; Ke, Chang-Ce; Ma, Shao-Xia; Zhang, Ru-Liang; Liu, Lei

2018-04-01

Nitrogen doped hollow carbon spheres (NHCSs) with tunable surface morphology have been prepared through one-pot carbonization method by using melamine-formaldehyde spheres as template and resorcinol-based resin as carbon precursor in ethanol-water solution. Well-dispersed NHCSs with particle size of 800 nm were obtained and the surface of NHCSs turn from smooth to tough, wrinkled, and finally concave by increasing the ethanol concentration. The fabricated NHCSs possessed high nitrogen content (3.99-4.83%) and hierarchical micro-dual mesoporous structure with surface area range of 265-405 m2 g-1 and total pore volume of 0.18-0.29 cm3 g-1, which contributed to high specific capacitance, excellent rate capability and long cycle life.

Reduction Expansion Synthesis as Strategy to Control Nitrogen Doping Level and Surface Area in Graphene

Directory of Open Access Journals (Sweden)

Russell Canty

2015-10-01

Full Text Available Graphene sheets doped with nitrogen were produced by the reduction-expansion (RES method utilizing graphite oxide (GO and urea as precursor materials. The simultaneous graphene generation and nitrogen insertion reactions are based on the fact that urea decomposes upon heating to release reducing gases. The volatile byproducts perform two primary functions: (i promoting the reduction of the GO and (ii providing the nitrogen to be inserted in situ as the graphene structure is created. Samples with diverse urea/GO mass ratios were treated at 800 °C in inert atmosphere to generate graphene with diverse microstructural characteristics and levels of nitrogen doping. Scanning electron microscopy (SEM and transmission electron microscopy (TEM were used to study the microstructural features of the products. The effects of doping on the samples structure and surface area were studied by X-ray diffraction (XRD, Raman Spectroscopy, and Brunauer Emmet Teller (BET. The GO and urea decomposition-reduction process as well as nitrogen-doped graphene stability were studied by thermogravimetric analysis (TGA coupled with mass spectroscopy (MS analysis of the evolved gases. Results show that the proposed method offers a high level of control over the amount of nitrogen inserted in the graphene and may be used alternatively to control its surface area. To demonstrate the practical relevance of these findings, as-produced samples were used as electrodes in supercapacitor and battery devices and compared with conventional, thermally exfoliated graphene.

Clean Air Markets - Monitoring Surface Water Chemistry

Science.gov (United States)

Learn about how EPA uses Long Term Monitoring (LTM) and Temporily Integrated Monitoring of Ecosystems (TIME) to track the effect of the Clean Air Act Amendments on acidity of surface waters in the eastern U.S.

Passive monitoring techniques for evaluating atmospheric ozone and nitrogen exposure and deposition to California ecosystems

Science.gov (United States)

Mark E. Fenn; Andrzej Bytnerowicz; Susan L. Schilling

2018-01-01

Measuring the exposure of ecosystems to ecologically relevant pollutants is needed for evaluating ecosystem effects and to identify regions and resources at risk. In California, ozone (O3) and nitrogen (N) pollutants are of greatest concern for ecological effects. "Passive" monitoring methods have been developed to obtain spatially...

Analysis of hyperspectral field radiometric data for monitoring nitrogen concentration in rice crops

Science.gov (United States)

Stroppiana, D.; Boschetti, M.; Confalonieri, R.; Bocchi, S.; Brivio, P. A.

2005-10-01

Monitoring crop conditions and assessing nutrition requirements is fundamental for implementing sustainable agriculture. Rational nitrogen fertilization is of particular importance in rice crops in order to guarantee high production levels while minimising the impact on the environment. In fact, the typical flooded condition of rice fields can be a significant source of greenhouse gasses. Information on plant nitrogen concentration can be used, coupled with information about the phenological stage, to plan strategies for a rational and spatially differentiated fertilization schedule. A field experiment was carried out in a rice field Northern Italy, in order to evaluate the potential of field radiometric measurements for the prediction of rice nitrogen concentration. The results indicate that rice reflectance is influenced by nitrogen supply at certain wavelengths although N concentration cannot be accurately predicted based on the reflectance measured at a given wavelength. Regression analysis highlighted that the visible region of the spectrum is most sensitive to plant nitrogen concentration when reflectance measures are combined into a spectral index. An automated procedure allowed the analysis of all the possible combinations into a Normalized Difference Index (NDI) of the narrow spectral bands derived by spectral resampling of field measurements. The derived index appeared to be least influenced by plant biomass and Leaf Area Index (LAI) providing a useful approach to detect rice nutritional status. The validation of the regressive model showed that the model is able to predict rice N concentration (R2=0.55 [p<0.01] RRMSE=29.4; modelling efficiency close to the optimum value).

Surface Damage and Treatment by Impact of a Low Temperature Nitrogen Jet

Science.gov (United States)

Laribou, Hicham; Fressengeas, Claude; Entemeyer, Denis; Jeanclaude, Véronique; Tazibt, Abdel

2011-01-01

Nitrogen jets under high pressure and low temperature have been introduced recently. The process consists in projecting onto a surface a low temperature jet obtained from releasing the liquid nitrogen stored in a high pressure tank (e.g. 3000 bars) through a nozzle. It can be used in a range of industrial applications, including surface treatment or material removal through cutting, drilling, striping and cleaning. The process does not generate waste other than the removed matter, and it only releases neutral gas into the atmosphere. This work is aimed at understanding the mechanisms of the interaction between the jet and the material surface. Depending on the impacted material, the thermo-mechanical shock and blast effect induced by the jet can activate a wide range of damage mechanisms, including cleavage, crack nucleation and spalling, as well as void expansion and localized ductile failure. The test parameters (standoff distance, dwell time, operating pressure) play a role in selecting the dominant damage mechanism, but combinations of these various modes are usually present. Surface treatment through phase transformation or grain fragmentation in a layer below the surface can also be obtained by adequate tuning of the process parameters. In the current study, work is undertaken to map the damage mechanisms in metallic materials as well as the influence of the test parameters on damage, along with measurements of the thermo-mechanical conditions (impact force, temperature) in the impacted area.

LRAD surface monitoring results at TA-21

International Nuclear Information System (INIS)

Bounds, J.A.

1995-01-01

In August/September 1994, NIS-6 personnel used LRAD soil surface monitor technology to characterize the extent of alpha contamination on the surface of a parking lot adjacent to TA-21, LANL, known as Material Disposal Area B. This report documents that monitoring. Based on this survey, there is no reason for concern about significant contamination in the parking area as a whole, although unexpected small hot spots could exist between the grid points where monitoring was performed. However, the grouping of high readings on the east side of the parking area does point to possible contamination at the level of 100 dpm/100 cm 2 or less (above background). Further monitoring or remediation of this area seems appropriate. In addition, because this was an alpha survey, one cannot rule out contamination under the asphalt or possibly between layers if it was paved more than once

[Bioactivity of ultraviolet ray-treated titanium surface in nitrogen storing environment].

Science.gov (United States)

Wang, Heng; Shang, Ren; Guan, Yun; Wang, Yan; Teng, Wei

2013-05-01

To evaluate the adhesion, proliferation and differentiation of osteoblast-like cells on the ultraviolet (UV)-treated titanium in different storing environment, and to find a way to enhance the bioactivity of titanium and to prevent its age-related degradation. Acid-etched titanium disks stored under ambient conditions for 4 weeks and treated with UV light for 48 h.Then disks were divided into three groups and placed in a sealed container for 0 h (no-stored,NO group) , 4 weeks (air-stored, AS group) or in a sealed container filled with nitrogen for 4 weeks (nitrogen-stored,NS group) respectively. A group of UV-untreated titanium served as negative control (NC group).The surface morphology was evaluated using scanning electron microscopy (SEM), and hydrophilicity of disks were measured using contact angle measuring device. Cell counting kit-8 was used to measure the cell adhesion and proliferation. Cell differentiation was evaluated by testing alkaline phosphatase (ALP) activity using ALP reagent kit. There was no difference in surface topography among groups.Contact angels in NS group [(67.70 ± 3.59)°] and NO group [(0.70 ± 0.28)°] were smaller than the others (P 0.05). Osteoblast-like cells had an abundant spread on NS and NO group during 2 h incubation, but did not exactly spread on AS and NC group after incubation for 4 h. No difference were found in ALP among groups. UV treatment can enhance bioactivity of titanium, and nitrogen storage can slow down its biological aging.

Radiological monitoring. Controlling surface water pollution

International Nuclear Information System (INIS)

Morin, Maxime

2018-01-01

Throughout France, surface waters (from rivers to brooks) located at the vicinity of nuclear or industrial sites, are subject to regular radiological monitoring. An example is given with the radiological monitoring of a small river near La Hague Areva's plant, where contaminations have been detected with the help of the French IRSN nuclear safety research organization. The sampling method and various measurement types are described

Using stable isotopes of carbon and nitrogen as in-situ tracers for monitoring the natural attenuation of explosives

National Research Council Canada - National Science Library

Miyares, Paul H

1999-01-01

The use of carbon and nitrogen stable isotope measurements from TNT was examined as a possible tool for monitoring the natural attenuation of TNT incubation studies of spiked soil samples were conducted...

A mesocosm study using four native Hawaiian plants to assess nitrogen accumulation under varying surface water nitrogen concentrations.

Science.gov (United States)

Unser, C U; Bruland, G L; Hood, A; Duin, K

2010-01-01

Accumulation of nitrogen (N) by native Hawaiian riparian plants from surface water was measured under a controlled experimental mesocosm setting. Four species, Cladium jamaicense, Cyperus javanicus, Cyperus laevigatus, and Cyperus polystachyos were tested for their ability to survive in coconut fiber coir log media with exposure to differing N concentrations. It was hypothesized that the selected species would have significantly different tissue total nitrogen (TN) concentrations, aboveground biomass, and TN accumulation rates because of habitat preference and physiological growth differences. A general linear model (GLM) analysis of variance (ANOVA) determined that species differences accounted for the greatest proportion of variance in tissue TN concentration, aboveground biomass growth, and accumulation rates, when compared with the other main effects (i.e. N concentration, time) and their interactions. A post hoc test of means demonstrated that C. jamaicense had significantly higher tissue TN concentration, aboveground biomass growth, and accumulation rates than the other species under all N concentrations. It was also hypothesized that tissue TN concentrations and biomass growth would increase in plants exposed to elevated N concentrations, however data did not support this hypothesis. Nitrogen accumulation rates by species were controlled by differences in plant biomass growth.

Application of Response Surface Methodology for Optimization of Urea Grafted Multi walled Carbon Nano tubes in Enhancing Nitrogen Use Efficiency and Nitrogen Uptake by Paddy Plants

International Nuclear Information System (INIS)

Yatim, N. M.; Shaaban, A.; Dimin, M. F.; Yusof, F.; Abo Razak, J.

2016-01-01

Efficient use of urea fertilizer (UF) as important nitrogen (N) source in the world’s rice production has been a concern. Carbon-based materials developed to improve UF performance still represent a great challenge to be formulated for plant nutrition. Advanced N nano carrier is developed based on functionalized multi wall carbon nano tubes (f-MWCNTs) grafted with UF to produce urea-multi wall carbon nano tubes (UF-MWCNTs) for enhancing the nitrogen uptake (NU) and use efficiency (NUE). The grafted N can be absorbed and utilized by rice efficiently to overcome the N loss from soil-plant systems. The individual and interaction effect between the specified factors of f-MWCNTs amount (0.10-0.60 wt%) and functionalization reflux time (12-24 hrs) with the corresponding responses (NUE, NU) were structured via the Response Surface Methodology (RSM) based on five-level CCD. The UF-MWCNTs with optimized 0.5 wt% f-MWCNTs treated at 21 hrs reflux time achieve tremendous NUE up to 96% and NU at 1180 mg/pot. Significant model terms (Þ value < 0.05) for NUE and NU responses were confirmed by the ANOVA. Homogeneous dispersion of UF-MWCNTs was observed via FESEM and TEM. The chemical changes were monitored by FT-IR and Raman spectroscopy. Hence, this UF-MWCNTs’ approach provides a promising strategy in enhancing plant nutrition for rice.

Atomic force microscopy of surface topography of nitrogen plasma treated steel

CERN Document Server

Mahboubi, F

2002-01-01

Nitriding of steels, using plasma environments has been practiced for many years. A lot of efforts have been put on developing new methods, such as plasma immersion ion implantation (Pl sup 3) and radio frequency (RF) plasma nitriding, for mass transfer of nitrogen into the surface of the work piece. This article presents the results obtained from an in depth investigation of the surface morphology of the treated samples, carried out using an atomic force microscope. Samples from a microalloyed steel, were treated by both methods for 5 hours at different temperatures ranging from 350 to 550 sup d eg sup C in 75% N sub 2 -25% H sub 2 atmosphere. It has been found that the surface of the samples treated by PI sup 3 technique, although having more favorable properties, were rougher than the surfaces treated by RF plasma nitriding.

Nitrogen-doped carbon monolith for alkaline supercapacitors and understanding nitrogen-induced redox transitions.

Science.gov (United States)

Wang, Da-Wei; Li, Feng; Yin, Li-Chang; Lu, Xu; Chen, Zhi-Gang; Gentle, Ian R; Lu, Gao Qing; Cheng, Hui-Ming

2012-04-23

A nitrogen-doped porous carbon monolith was synthesized as a pseudo-capacitive electrode for use in alkaline supercapacitors. Ammonia-assisted carbonization was used to dope the surface with nitrogen heteroatoms in a way that replaced carbon atoms but kept the oxygen content constant. Ammonia treatment expanded the micropore size-distributions and increased the specific surface area from 383 m(2) g(-1) to 679 m(2) g(-1). The nitrogen-containing porous carbon material showed a higher capacitance (246 F g(-1)) in comparison with the nitrogen-free one (186 F g(-1)). Ex situ electrochemical spectroscopy was used to investigate the evolution of the nitrogen-containing functional groups on the surface of the N-doped carbon electrodes in a three-electrode cell. In addition, first-principles calculations were explored regarding the electronic structures of different nitrogen groups to determine their relative redox potentials. We proposed possible redox reaction pathways based on the calculated redox affinity of different groups and surface analysis, which involved the reversible attachment/detachment of hydroxy groups between pyridone and pyridine. The oxidation of nitrogen atoms in pyridine was also suggested as a possible reaction pathway. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Calibration of alpha surface contamination monitor

International Nuclear Information System (INIS)

Freitas, I.S.M. de; Goncalez, O.L.

1990-01-01

In this work, the results, as well as the methodology, of the calibration of an alpha surface contamination monitor are presented. The calibration factors are obtained by least-squares fitting with effective variance. (author)

Dynamics of liquid nitrogen cooling process of solid surface at wetting contact coefficient

International Nuclear Information System (INIS)

Smakulski, P; Pietrowicz, S

2015-01-01

Liquid cryogens cooling by direct contact is very often used as a method for decreasing the temperature of electronic devices or equipment i.e. HTS cables. Somehow, cooldown process conducted in that way could not be optimized, because of cryogen pool boiling characteristic and low value of the heat transfer coefficient. One of the possibilities to increase the efficiency of heat transfer, as well as the efficiency of cooling itself, it is to use a spray cooling method. The paper shows dynamics analysis of liquid nitrogen cooling solid surface process. The model of heat transfer for the single droplet of liquid nitrogen, which hits on a flat and smooth surface with respect to the different Weber numbers, is shown. Temperature profiles in calculation domains are presented, as well as the required cooling time. The numerical calculations are performed for different initial and boundary conditions, to study how the wetting contact coefficient is changing, and how it contributed to heat transfer between solid and liquid cryogen. (paper)

Excitation of surface plasmon polariton modes with multiple nitrogen vacancy centers in single nanodiamonds

International Nuclear Information System (INIS)

Kumar, Shailesh; Lausen, Jens L; Andersen, Sebastian K H; Roberts, Alexander S; Radko, Ilya P; Bozhevolnyi, Sergey I; Garcia-Ortiz, Cesar E; Smith, Cameron L C; Kristensen, Anders

2016-01-01

Nitrogen-vacancy (NV) centers in diamonds are interesting due to their remarkable characteristics that are well suited to applications in quantum-information processing and magnetic field sensing, as well as representing stable fluorescent sources. Multiple NV centers in nanodiamonds (NDs) are especially useful as biological fluorophores due to their chemical neutrality, brightness and room-temperature photostability. Furthermore, NDs containing multiple NV centers also have potential in high-precision magnetic field and temperature sensing. Coupling NV centers to propagating surface plasmon polariton (SPP) modes gives a base for lab-on-a-chip sensing devices, allows enhanced fluorescence emission and collection which can further enhance the precision of NV-based sensors. Here, we investigate coupling of multiple NV centers in individual NDs to the SPP modes supported by silver surfaces protected by thin dielectric layers and by gold V-grooves (VGs) produced via the self-terminated silicon etching. In the first case, we concentrate on monitoring differences in fluorescence spectra obtained from a source ND, which is illuminated by a pump laser, and from a scattering ND illuminated only by the fluorescence-excited SPP radiation. In the second case, we observe changes in the average NV lifetime when the same ND is characterized outside and inside a VG. Fluorescence emission from the VG terminations is also observed, which confirms the NV coupling to the VG-supported SPP modes. (paper)

Excitation of surface plasmon polariton modes with multiple nitrogen vacancy centers in single nanodiamonds

Science.gov (United States)

Kumar, Shailesh; Lausen, Jens L.; Garcia-Ortiz, Cesar E.; Andersen, Sebastian K. H.; Roberts, Alexander S.; Radko, Ilya P.; Smith, Cameron L. C.; Kristensen, Anders; Bozhevolnyi, Sergey I.

2016-02-01

Nitrogen-vacancy (NV) centers in diamonds are interesting due to their remarkable characteristics that are well suited to applications in quantum-information processing and magnetic field sensing, as well as representing stable fluorescent sources. Multiple NV centers in nanodiamonds (NDs) are especially useful as biological fluorophores due to their chemical neutrality, brightness and room-temperature photostability. Furthermore, NDs containing multiple NV centers also have potential in high-precision magnetic field and temperature sensing. Coupling NV centers to propagating surface plasmon polariton (SPP) modes gives a base for lab-on-a-chip sensing devices, allows enhanced fluorescence emission and collection which can further enhance the precision of NV-based sensors. Here, we investigate coupling of multiple NV centers in individual NDs to the SPP modes supported by silver surfaces protected by thin dielectric layers and by gold V-grooves (VGs) produced via the self-terminated silicon etching. In the first case, we concentrate on monitoring differences in fluorescence spectra obtained from a source ND, which is illuminated by a pump laser, and from a scattering ND illuminated only by the fluorescence-excited SPP radiation. In the second case, we observe changes in the average NV lifetime when the same ND is characterized outside and inside a VG. Fluorescence emission from the VG terminations is also observed, which confirms the NV coupling to the VG-supported SPP modes.

Monitoring System for ALICE Surface Areas

CERN Document Server

Demirbasci, Oguz

2016-01-01

I have been at CERN for 12 weeks within the scope of Summer Student Programme working on a monitoring system project for surface areas of the ALICE experiment during this period of time. The development and implementation of a monitoring system for environmental parameters in the accessible areas where a cheap hardware setup can be deployed were aim of this project. This report explains how it was developed by using Arduino, Raspberry PI, WinCC OA and DIM protocol.

Real-time continuous nitrate monitoring in Illinois in 2013

Science.gov (United States)

Warner, Kelly L.; Terrio, Paul J.; Straub, Timothy D.; Roseboom, Donald; Johnson, Gary P.

2013-01-01

Many sources contribute to the nitrogen found in surface water in Illinois. Illinois is located in the most productive agricultural area in the country, and nitrogen fertilizer is commonly used to maximize corn production in this area. Additionally, septic/wastewater systems, industrial emissions, and lawn fertilizer are common sources of nitrogen in urban areas of Illinois. In agricultural areas, the use of fertilizer has increased grain production to meet the needs of a growing population, but also has resulted in increases in nitrogen concentrations in many streams and aquifers (Dubrovsky and others, 2010). The urban sources can increase nitrogen concentrations, too. The Federal limit for nitrate nitrogen in water that is safe to drink is 10 milligrams per liter (mg/L) (http://water.epa.gov/drink/contaminants/basicinformation/nitrate.cfm, accessed on May 24, 2013). In addition to the concern with nitrate nitrogen in drinking water, nitrogen, along with phosphorus, is an aquatic concern because it feeds the intensive growth of algae that are responsible for the hypoxic zone in the Gulf of Mexico. The largest nitrogen flux to the waters feeding the Gulf of Mexico is from Illinois (Alexander and others, 2008). Most studies of nitrogen in surface water and groundwater include samples for nitrate nitrogen collected weekly or monthly, but nitrate concentrations can change rapidly and these discrete samples may not capture rapid changes in nitrate concentrations that can affect human and aquatic health. Continuous monitoring for nitrate could inform scientists and water-resource managers of these changes and provide information on the transport of nitrate in surface water and groundwater.

Using a nitrogen dielectric barrier discharge for surface treatment

International Nuclear Information System (INIS)

Borcia, G; Anderson, C A; Brown, N M D

2005-01-01

In this paper, continuing previous work, we report on the installation and the testing of an experimental dielectric barrier discharge (DBD) reactor run in a controlled atmospheric pressure gaseous environment other than air. Here, the effects of a N 2 -DBD treatment on the surface of a test polymer material (UHMW polyethylene) are examined, reported, discussed and compared to results obtained previously following air-DBD treatment. Surface analysis and characterization were performed using x-ray photoelectron spectroscopy, contact angle measurement and scanning electron microscopy before and following the DBD processing described. The discharge parameters used were correlated with the changes in the surface characteristics found following DBD treatments of various durations in a nitrogen atmosphere. The work focuses on the control of the gaseous environment supporting the discharge and on the possibility of overcoming the potentially dominant effect of reactive oxygen-related species, derived from any residual air present. The results obtained underline the very high reactivity of such species in the discharge, but are encouraging in respect of the possibility of the implantation or generation of functional groups other than oxygen-related ones at the surface of interest. The processing conditions concerned simulate 'real' continuous high speed processing, allowing the planning of further experiments, where various gaseous mixtures of the type X + N 2 will be used for controlled surface functionalization

Integration of nitrogen dynamics into the Noah-MP land surface model v1.1 for climate and environmental predictions

International Nuclear Information System (INIS)

Cai, X.; Zhang, X.

2016-01-01

Climate and terrestrial biosphere models consider nitrogen an important factor in limiting plant carbon uptake, while operational environmental models view nitrogen as the leading pollutant causing eutrophication in water bodies. The community Noah land surface model with multi-parameterization options (Noah-MP) is unique in that it is the next-generation land surface model for the Weather Research and Forecasting meteorological model and for the operational weather/climate models in the National Centers for Environmental Prediction. Here in this study, we add a capability to Noah-MP to simulate nitrogen dynamics by coupling the Fixation and Uptake of Nitrogen (FUN) plant model and the Soil and Water Assessment Tool (SWAT) soil nitrogen dynamics. This model development incorporates FUN's state-of-the-art concept of carbon cost theory and SWAT's strength in representing the impacts of agricultural management on the nitrogen cycle. Parameterizations for direct root and mycorrhizal-associated nitrogen uptake, leaf retranslocation, and symbiotic biological nitrogen fixation are employed from FUN, while parameterizations for nitrogen mineralization, nitrification, immobilization, volatilization, atmospheric deposition, and leaching are based on SWAT. The coupled model is then evaluated at the Kellogg Biological Station – a Long Term Ecological Research site within the US Corn Belt. Results show that the model performs well in capturing the major nitrogen state/flux variables (e.g., soil nitrate and nitrate leaching). Furthermore, the addition of nitrogen dynamics improves the modeling of net primary productivity and evapotranspiration. The model improvement is expected to advance the capability of Noah-MP to simultaneously predict weather and water quality in fully coupled Earth system models.

Spin properties of dense near-surface ensembles of nitrogen-vacancy centers in diamond

Science.gov (United States)

Tetienne, J.-P.; de Gille, R. W.; Broadway, D. A.; Teraji, T.; Lillie, S. E.; McCoey, J. M.; Dontschuk, N.; Hall, L. T.; Stacey, A.; Simpson, D. A.; Hollenberg, L. C. L.

2018-02-01

We present a study of the spin properties of dense layers of near-surface nitrogen-vacancy (NV) centers in diamond created by nitrogen ion implantation. The optically detected magnetic resonance contrast and linewidth, spin coherence time, and spin relaxation time, are measured as a function of implantation energy, dose, annealing temperature, and surface treatment. To track the presence of damage and surface-related spin defects, we perform in situ electron spin resonance spectroscopy through both double electron-electron resonance and cross-relaxation spectroscopy on the NV centers. We find that, for the energy (4 -30 keV) and dose (5 ×1011-1013ions/cm 2 ) ranges considered, the NV spin properties are mainly governed by the dose via residual implantation-induced paramagnetic defects, but that the resulting magnetic sensitivity is essentially independent of both dose and energy. We then show that the magnetic sensitivity is significantly improved by high-temperature annealing at ≥1100 ∘C . Moreover, the spin properties are not significantly affected by oxygen annealing, apart from the spin relaxation time, which is dramatically decreased. Finally, the average NV depth is determined by nuclear magnetic resonance measurements, giving ≈10 -17 nm at 4-6 keV implantation energy. This study sheds light on the optimal conditions to create dense layers of near-surface NV centers for high-sensitivity sensing and imaging applications.

Further contributions to the understanding of nitrogen removal in waste stabilization ponds.

Science.gov (United States)

Bastos, R K X; Rios, E N; Sánchez, I A

2018-06-01

A set of experiments were conducted in Brazil in a pilot-scale waste stabilization pond (WSP) system (a four-maturation-pond series) treating an upflow anaerobic sludge blanket (UASB) reactor effluent. Over a year and a half the pond series was monitored under two flow rate conditions, hence also different hydraulic retention times and surface loading rates. On-site and laboratory trials were carried out to assess: (i) ammonia losses by volatilization using acrylic capture chambers placed at the surface of the ponds; (ii) organic nitrogen sedimentation rates using metal buckets placed at the bottom of the ponds for collecting settled particulate matter; (iii) nitrogen removal by algal uptake based on the nitrogen content of the suspended particulate matter in samples from the ponds' water column. In addition, nitrification and denitrification rates were measured in laboratory-based experiments using pond water and sediment samples. The pond system achieved high nitrogen removal (69% total nitrogen and 92% ammonia removal). The average total nitrogen removal rates varied from 10,098 to 3,849 g N/ha·d in the first and the last ponds, respectively, with the following fractions associated with the various removal pathways: (i) 23.5-45.6% sedimentation of organic nitrogen; (ii) 13.1-27.8% algal uptake; (iii) 1.2-3.1% ammonia volatilization; and (iv) 0.15-0.34% nitrification-denitrification.

Interaction of dense nitrogen plasma with SS304 surface using APF plasma focus device

Science.gov (United States)

Afrashteh, M.; Habibi, M.; Heydari, E.

2012-04-01

The nitridation of SS304 surfaces is obtained by irradiating nitrogen ions from Amirkabir plasma focus device, which use multiple focus deposition shots at optimum distance 10 cm from the anode. The Vickers Micro-Hardness values are improved more than twice for the nitrided samples comparing to the nonnitrided ones. The X-ray diffraction (XRD) analysis is carried out in order to explore the phase changes in the near surface structure of the metals. The results of Scanning Electron Microscopy (SEM) indicate changes in surface morphology which are the emergence of smooth and uniform film on the surface of the nitrided metals.

Influence of nitrogen surface functionalities on the catalytic activity of activated carbon in low temperature SCR of NOx with NH3

International Nuclear Information System (INIS)

Szymanski, Grzegorz S.; Grzybek, Teresa; Papp, Helmut

2004-01-01

The reduction of nitrogen oxide with ammonia was studied using carbon catalysts with chemically modified surfaces. Carbon samples with different surface chemistry were obtained from commercial activated carbon D43/1 (CarboTech, Essen, Germany) by chemical modification involving oxidation with conc. nitric acid (DOx) (1); high temperature treatment (=1000K) under vacuum (DHT) (2); or in ammonia (DHTN, DOxN) (3). Additionally, a portion of the DOx sample was promoted with iron(III) ions (DOxFe). The catalytic tests were performed in a microreactor at a temperature range of 413-573K. The carbon sample annealed under vacuum (DHT) showed the lowest activity. The formation of surface acidic surface oxides by nitric acid treatment (DOx) enhanced the catalytic activity only slightly. However, as can be expected, subsequent promotion of the DOx sample with iron(III) ions increased drastically its catalytic activity. However, this was accompanied by some loss of selectivity, i.e. formation of N 2 O as side product. This effect can be avoided using ammonia-treated carbons which demonstrated reasonable activity with simultaneous high selectivity. The most active and selective among them was the sample that was first oxidized with nitric acid and then heated in an ammonia stream (DOxN). A correlation between catalytic activity and surface nitrogen content was observed. Surface nitrogen species seem to play an important role in catalytic selective reduction of nitrogen oxide with ammonia, possibly facilitating NO 2 formation (a reaction intermediate) as a result of easier chemisorption of oxygen and nitrogen oxide

Investigation of fluorine adsorption on nitrogen doped MgAl{sub 2}O{sub 4} surface by first-principles

Energy Technology Data Exchange (ETDEWEB)

Lv, Xiaojun; Xu, Zhenming [School of Metallurgy and Environment, Central South University, Changsha 410083 (China); Li, Jie, E-mail: 15216105346@163.com [School of Metallurgy and Environment, Central South University, Changsha 410083 (China); Chen, Jiangan [Faculty of Resource and Environmental Engineering, Jiangxi University of Science and Technology, Ganzhou 341000 (China); Liu, Qingsheng [Faculty of Metallurgical and Chemical Engineering, Jiangxi University of Science and Technology, Ganzhou 341000 (China)

2016-07-15

Graphical abstract: First-principles calculations indicate that MgAl{sub 2}O{sub 4} surface is fluorine-loving, but hydrophobic. N doped MgAl{sub 2}O{sub 4} (100) surface structure shows the highest fluorine adsorption performance and fluorine atom is more preferentially adsorbed on the Mg-Al bridge site. The fluorine adsorption intensity follow this order: N doped MgAl{sub 2}O{sub 4} (100) > Al{sub 2}O{sub 3} (0001) > MgAl{sub 2}O{sub 4} (100) > MgO (100). N doped MgAl{sub 2}O{sub 4} is a promising candidate for fluorine removal. - Highlights: • MgAl{sub 2}O{sub 4} surface is fluorine-loving, not hydrophilic. • Fluorine preferentially adsorbs on the Mg-Al bridge site. • Adsorption intensity follow this order: N doped MgAl{sub 2}O{sub 4} > Al{sub 2}O{sub 3} > MgAl{sub 2}O{sub 4} > MgO. • Excellent adsorption performance attributes to electron compensation of N atom. • Nitrogen doped MgAl{sub 2}O{sub 4} is a promising candidate for fluorine removal. - Abstract: The nature of fluorine adsorption on pure and N doped MgAl{sub 2}O{sub 4} surface has been investigated by first-principles calculations based on the density functional theory. Calculated results indicate that MgAl{sub 2}O{sub 4} surface is fluorine-loving, not hydrophilic. Nitrogen doped MgAl{sub 2}O{sub 4} (100) surface shows the highest fluorine adsorption performance and fluorine atom preferentially adsorbs on the Mg-Al bridge site. The fluorine adsorption intensity follow this order: Nitrogen doped MgAl{sub 2}O{sub 4} (100) > Al{sub 2}O{sub 3} (0001) > MgAl{sub 2}O{sub 4} (100) > MgO (100). In-depth PDOS analysis suggested that 2p orbitals of F atom strongly hybridized with 3s- and 3p-orbitals of Al atom contribute to its high adsorption intensity. According to the analysis of Hirshfeld charge, the excellent fluorine adsorption performance of nitrogen doped MgAl{sub 2}O{sub 4} attributes to the electron compensation effect of nitrogen atom and strong electrostatic interactions. All these

Reducing nitrogen leaching from fertilizers to surface waters: catchment specific indicators of economic benefits

DEFF Research Database (Denmark)

Andersen, Mikael Skou; Levin, Gregor; Odgaard, Mette Vestergaard

2018-01-01

We explore with impact pathway methodology the economic benefits of reducing nitrogen leaching to transitional surface waters, as expected for a proportionality test under the EU’s Water Framework Directive article 4. Ten different catchments is analyzed for a policy scenario where downstream dis...

Cell surface acid-base properties of the cyanobacterium Synechococcus: Influences of nitrogen source, growth phase and N:P ratios

Science.gov (United States)

Liu, Yuxia; Alessi, D. S.; Owttrim, G. W.; Kenney, J. P. L.; Zhou, Qixing; Lalonde, S. V.; Konhauser, K. O.

2016-08-01

The distribution of many trace metals in the oceans is controlled by biological uptake. Recently, Liu et al. (2015) demonstrated the propensity for a marine cyanobacterium to adsorb cadmium from seawater, suggesting that cell surface reactivity might also play an important role in the cycling of metals in the oceans. However, it remains unclear how variations in cyanobacterial growth rates and nutrient supply might affect the chemical properties of their cellular surfaces. In this study we used potentiometric titrations and Fourier Transform Infrared (FT-IR) spectrometry to profile the key metabolic changes and surface chemical responses of a Synechococcus strain, PCC 7002, during different growth regimes. This included testing various nitrogen (N) to phosphorous (P) ratios (both nitrogen and phosphorous dependent), nitrogen sources (nitrate, ammonium and urea) and growth stages (exponential, stationary, and death phase). FT-IR spectroscopy showed that varying the growth substrates on which Synechococcus cells were cultured resulted in differences in either the type or abundance of cellular exudates produced or a change in the cell wall components. Potentiometric titration data were modeled using three distinct proton binding sites, with resulting pKa values for cells of the various growth conditions in the ranges of 4.96-5.51 (pKa1), 6.67-7.42 (pKa2) and 8.13-9.95 (pKa3). According to previous spectroscopic studies, these pKa ranges are consistent with carboxyl, phosphoryl, and amine groups, respectively. Comparisons between the titration data (for the cell surface) and FT-IR spectra (for the average cellular changes) generally indicate (1) that the nitrogen source is a greater determinant of ligand concentration than growth phase, and (2) that phosphorus limitation has a greater impact on Synechococcus cellular and extracellular properties than does nitrogen limitation. Taken together, these techniques indicate that nutritional quality during cell growth can

Body surface mounted biomedical monitoring system using Bluetooth.

Science.gov (United States)

Nambu, Masayuki

2007-01-01

Continuous monitoring in daily life is important for the health condition control of the elderly. However, portable or wearable devices need to carry by user on their own will. On the other hand, implantation sensors are not adoptable, because of generic users dislike to insert the any object in the body for monitoring. Therefore, another monitoring system of the health condition to carry it easily is necessary. In addition, ID system is necessary even if the subject live with few families. Furthermore, every measurement system should be wireless system, because not to obstruct the daily life of the user. In this paper, we propose the monitoring system, which is mounted on the body surface. This system will not obstruct the action or behavior of user in daily life, because this system attached the body surface on the back of the user. In addition, this system has wireless communication system, using Bluetooth, and acquired data transfer to the outside of the house via the Internet.

Microbial nitrogen transformation potential in surface run-off leachate from a tropical landfill

International Nuclear Information System (INIS)

Mangimbulude, Jubhar C.; Straalen, Nico M. van; Röling, Wilfred F.M.

2012-01-01

combination of nitrate reduction to nitrite and anammox. Such optimization of microbial nitrogen transformations can contribute to alleviating the ammonium discharge to surface water draining the landfill.

Surface Treatment of PEOT/PBT (55/45 with a Dielectric Barrier Discharge in Air, Helium, Argon and Nitrogen at Medium Pressure

Directory of Open Access Journals (Sweden)

Pieter Cools

2018-03-01

Full Text Available This work describes the surface modification of 300PEO-PEOT/PBT 55/45 thin films using a medium pressure dielectric barrier discharge system operated in argon, helium, nitrogen or dry air to improve cell-surface interactions of this established biomaterial. The first part of the paper describes the optimization of the plasma processing parameters using water contact angle goniometry. The optimized samples are then characterized for changes in surface topography and surface chemical composition using atomic force microscopy (AFM and X-ray fluorescence spectroscopy (XPS respectively. For all plasma treatments, a pronounced increase in surface wettability was observed, of which the extent is dependent on the used plasma discharge gas. Except for dry air, only minor changes in surface topography were noted, while XPS confirmed that the changes in wettability were mainly chemical in nature with the incorporation of 5–10% of extra oxygen as a variety of polar groups. Similarly, for the nitrogen plasma, 3.8% of nitrogen polar groups were additionally incorporated. Human foreskin fibroblast (HFF in vitro analysis showed that within the first 24 h after cell seeding, the effects on cell-surface interactivity were highly dependent on the used discharge gas, nitrogen plasma treatment being the most efficient. Differences between untreated and plasma-treated samples were less pronounced compared to other biodegradable materials, but a positive influence on cell adhesion and proliferation was still observed.

Effect of cooling rate on the survival of cryopreserved rooster sperm: Comparison of different distances in the vapor above the surface of the liquid nitrogen.

Science.gov (United States)

Madeddu, M; Mosca, F; Abdel Sayed, A; Zaniboni, L; Mangiagalli, M G; Colombo, E; Cerolini, S

2016-08-01

The aim of the present trial was to study the effect of different freezing rates on the survival of cryopreserved rooster semen packaged in straws. Slow and fast freezing rates were obtained keeping straws at different distances in the vapor above the surface of the nitrogen during freezing. Adult Lohmann roosters (n=27) were used. Two experiments were conducted. In Experiment 1, semen was packaged in straws and frozen comparing the distances of 1, 3 and 5cm in nitrogen vapor above the surface of the liquid nitrogen. In Experiment 2, the distances of 3, 7 and 10cm above the surfaces of the liquid nitrogen were compared. Sperm viability, motility and progressive motility and the kinetic variables were assessed in fresh and cryopreserved semen samples. The recovery rates after freezing/thawing were also calculated. In Experiment 1, there were no significant differences among treatments for all semen quality variables. In Experiment 2, the percentage of viable (46%) and motile (22%) sperm in cryopreserved semen was greater when semen was placed 3cm compared with 7 and 10cm in the vapor above the surface of the liquid nitrogen. The recovery rate of progressive motile sperm after thawing was also greater when semen was stored 3cm in the vapor above the surface of the liquid nitrogen. More rapid freezing rates are required to improve the survival of rooster sperm after cryopreservation and a range of distances from 1 to 5cm in nitrogen vapor above the surface of the liquid nitrogen is recommended for optimal sperm viability. Copyright © 2016 Elsevier B.V. All rights reserved.

Facile Synthesis of Nitrogen Doped Graphene Oxide from Graphite Flakes and Powders: A Comparison of Their Surface Chemistry.

Science.gov (United States)

Yokwana, Kholiswa; Ray, Sekhar C; Khenfouch, Mohammad; Kuvarega, Alex T; Mamba, Bhekie B; Mhlanga, Sabelo D; Nxumalo, Edward N

2018-08-01

Nitrogen-doped graphene oxide (NGO) nanosheets were prepared via a facile one-pot modified Hummer's approach at low temperatures using graphite powder and flakes as starting materials in the presence of a nitrogen precursor. It was found that the morphology, structure, composition and surface chemistry of the NGO nanosheets depended on the nature of the graphite precursor used. GO nanosheets doped with nitrogen atoms exhibited a unique structure with few thin layers and wrinkled sheets, high porosity and structural defects. NGO sheets made from graphite powder (NGOp) exhibited excellent thermal stability and remarkably high surface area (up to 240.53 m2 ·g-1) compared to NGO sheets made from graphite flakes (NGOf) which degraded at low temperatures and had an average surface area of 24.70 m2 ·g-1. NGOf sheets had a size range of 850 to 2200 nm while NGOp sheets demonstrated obviously small sizes (460-1600 nm) even when exposed to different pH conditions. The NGO nanosheets exhibited negatively charged surfaces in a wide pH range (1 to 12) and were found to be stable above pH 6. In addition, graphite flakes were found to be more suitable for the production of NGO as they produced high N-doping levels (0.65 to 1.29 at.%) compared to graphite powders (0.30 to 0.35 at.%). This study further demonstrates that by adjusting the amount of N source in the host GO, one can tailor its thermal stability, surface morphology, surface chemistry and surface area.

Recent Nitrogen Deposition In Poland Monitored With The Moss Pleurozium Schreberi

Directory of Open Access Journals (Sweden)

Kapusta Paweł

2014-07-01

Full Text Available In this study, atmospheric deposition of nitrogen was determined for Poland by moss biomonitoring. Nitrogen content was measured in the moss Pleurozium schreberi (Willd. ex Brid. Mitt. sampled in 2010 from 320 sites evenly distributed throughout the country. Mosses (green parts contained an average 1.56% nitrogen. The result places Poland among the European countries most polluted by airborne nitrogen. The highest nitrogen concentrations were found in mosses from the central and southern parts of the country, and the lowest in samples from some eastern and northern regions. Multiple regression showed that this variability was due mostly to nitrogen emissions from agricultural and industrial areas (moss nitrogen was positively associated with the consumption of mineral nitrogen fertilizers and the magnitude of particulate pollution. Some details of the spatial variability of the nitrogen data indicate that local and regional point sources of pollution (e.g., chemical plants played an important role in shaping the nitrogen deposition pattern

Low-Temperature Sol-Gel Synthesis of Nitrogen-Doped Anatase/Brookite Biphasic Nanoparticles with High Surface Area and Visible-Light Performance

Directory of Open Access Journals (Sweden)

Liang Jiang

2017-12-01

Full Text Available Nitrogen doping in combination with the brookite phase or a mixture of TiO2 polymorphs nanomaterials can enhance photocatalytic activity under visible light. Generally, nitrogen-dopedanatase/brookite mixed phases TiO2 nanoparticles obtained by hydrothermal or solvothermal method need to be at high temperature and with long time heating treatment. Furthermore, the surface areas of them are low (<125 m2/g. There is hardly a report on the simple and direct preparation of N-doped anatase/brookite mixed phase TiO2 nanostructures using sol-gel method at low heating temperature. In this paper, the nitrogen-doped anatase/brookite biphasic nanoparticles with large surface area (240 m2/g were successfully prepared using sol-gel method at low temperature (165 °C, and with short heating time (4 h under autogenous pressure. The obtained sample without subsequent annealing at elevated temperatures showed enhanced photocatalytic efficiency for the degradation of methyl orange (MO with 4.2-, 9.6-, and 7.5-fold visible light activities compared to P25 and the amorphous samples heated in muffle furnace with air or in tube furnace with a flow of nitrogen at 165 °C, respectively. This result was attributed to the synergistic effects of nitrogen doping, mixed crystalline phases, and high surface area.

Experimental identification of nitrogen-vacancy complexes in nitrogen implanted silicon

Science.gov (United States)

Adam, Lahir Shaik; Law, Mark E.; Szpala, Stanislaw; Simpson, P. J.; Lawther, Derek; Dokumaci, Omer; Hegde, Suri

2001-07-01

Nitrogen implantation is commonly used in multigate oxide thickness processing for mixed signal complementary metal-oxide-semiconductor and System on a Chip technologies. Current experiments and diffusion models indicate that upon annealing, implanted nitrogen diffuses towards the surface. The mechanism proposed for nitrogen diffusion is the formation of nitrogen-vacancy complexes in silicon, as indicated by ab initio studies by J. S. Nelson, P. A. Schultz, and A. F. Wright [Appl. Phys. Lett. 73, 247 (1998)]. However, to date, there does not exist any experimental evidence of nitrogen-vacancy formation in silicon. This letter provides experimental evidence through positron annihilation spectroscopy that nitrogen-vacancy complexes indeed form in nitrogen implanted silicon, and compares the experimental results to the ab initio studies, providing qualitative support for the same.

Investigation of nitrogen atom production in Ar/N2 and He/N2 surface wave plasmas

International Nuclear Information System (INIS)

Tabbal, M.; Kazopoulo, M.; Christidis, T.; Isber, S.

2000-01-01

Full text: There is presently great interest in nitrogen plasmas for surface coating processes. Such as the deposition of nitride thin films and surface treatment of materials. Indeed, nitrogen plasmas have been used to nitride the surface of ferrous and non-ferrous materials in order to improve their surface properties such as resistance to corrosion and hardness. Moreover, the design and development of nitrogen atom sources could be essential for the synthesis of gallium nitride (GaN), a wide band-gap semiconductor whose properties have revolutionized the microelectronics and optoelectronics industries. Correlations have been established between the density of active species in the process, namely atomic nitrogen (N) produced by the discharge and GaN film properties. Thus, it is of fundamental importance to investigate the N-atom production mechanisms in such discharges. N-atom production has been studied in pure N 2 surface-wave plasmas (SWP), as a function of operating parameters, namely gas pressure and electrical power. These studies indicate that the increase in the gas temperature (T g ) limits the N-atom production. One possible way of enhancing the N 2 dissociation rate ([N]/[N 2 ]) in the plasma could be the use of gas mixtures such as Ar/N 2 or He/N 2 . the aim of this paper is to characterize an Ar/N 2 and He/N 2 surface-wave discharge (SWD) by optical emission spectroscopy (OES), in order to determine the optimal plasma conditions in terms of [N]/[N 2 ]. The plasma is generated by a radio frequency (40.68 MHz) wave launcher. The effect of mixing N 2 with Ar and He on the production of N-atoms in the plasma was investigated at varying experimental conditions, such as operating pressure (4.5 and 7.5 Torr), electrical power (40 to 120 W), at a total gas flow of 250 sccm. It was found that [N]/[N 2 ] increases with the partial pressure of Ar in the mixture by a factor of about 8 at 120W. Such an enhancement is reduced at lower incident powers. On the

Characterization of nitrogen ice on Pluto's surface from 1-4 micron spectroscopy

Science.gov (United States)

Young, E.; Olkin, C.; Grundy, W.; Young, L.; Schmitt, B.; Tokunaga, A.; Owen, T.; Roush, T.; Terada, H.

Nitrogen ice is the predominant ice on Pluto's surface. Methane and CO have also been identified (e.g., Grundy & Buie 2001), but they are thought to be trace consituents relative to N2 , mainly because of the strength of nitrogen's 2.147 µm feature. It is assumed that the temperature of the surface N2 frost controls the column abundance of Pluto's atmosphere through vapor pressure equilibrium. The vapor pressures of CO and CH4 are about 5 and 10,000 times less than that of N2 at a typical temperature for Pluto's surface. There is spectroscopic evidence that CH4 ice exists as a dissolved constituent in a predominantly nitrogen ice matrix as well as separate, pure CH4 ice. It would be interesting to know what fraction of N2 ice is pure for purposes of modeling the surface/atmosphere interactions on Pluto. We present spectroscopic modeling to show that the fraction of pure N2 ice on Pluto is very small indeed - conservatively less than 6% by area. We will present spectral observations and modeling results from the IRTF1 , W.M. Keck2 and Subaru3 Observatories spanning 1.0 to 4.0 µm. We have implemented a Hapke model (Hapke 1993) to constrain the abundance and states of N2 ice and CH4 ice. The depth of the Pluto spectrum at 3.3 µm effectively limits the amount of pure N2 ice that can be present on Pluto. Grundy, W. M. & Buie, M. W. 2001, Icarus, 153, 248. Hapke, B. 1993, Theory of Reflectance and Emittance Spectroscopy, Cambridge Univ. Press, New York. 1 Based in part on data obtained at the Infrared Telescope Facility, which is operated by the University of Hawaii under Cooperative Agreement no. NCC 5-538 with the National Aeronautics and Space Administration, Science Mission Directorate, Planetary Astronomy Program. 2 The data presented herein were obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The 1

High density nitrogen-vacancy sensing surface created via He{sup +} ion implantation of {sup 12}C diamond

Energy Technology Data Exchange (ETDEWEB)

Kleinsasser, Ed E., E-mail: edklein@uw.edu [Department of Electrical Engineering, University of Washington, Seattle, Washington 98195-2500 (United States); Stanfield, Matthew M.; Banks, Jannel K. Q. [Department of Physics, University of Washington, Seattle, Washington 98195-1560 (United States); Zhu, Zhouyang; Li, Wen-Di [HKU-Shenzhen Institute of Research and Innovation (HKU-SIRI), Shenzhen 518000 (China); Department of Mechanical Engineering, The University of Hong Kong, Pokfulam, Hong Kong (China); Acosta, Victor M. [Department of Physics and Astronomy, Center for High Technology Materials, University of New Mexico, Albuquerque, New Mexico 87106 (United States); Watanabe, Hideyuki [Correlated Electronics Group, Electronics and Photonics Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 5, 1-1-1, Higashi, Tsukuba, Ibaraki 305-8565 (Japan); Itoh, Kohei M. [School of Fundamental Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522 (Japan); Fu, Kai-Mei C., E-mail: kaimeifu@uw.edu [Department of Electrical Engineering, University of Washington, Seattle, Washington 98195-2500 (United States); Department of Physics, University of Washington, Seattle, Washington 98195-1560 (United States)

2016-05-16

We present a promising method for creating high-density ensembles of nitrogen-vacancy centers with narrow spin-resonances for high-sensitivity magnetic imaging. Practically, narrow spin-resonance linewidths substantially reduce the optical and RF power requirements for ensemble-based sensing. The method combines isotope purified diamond growth, in situ nitrogen doping, and helium ion implantation to realize a 100 nm-thick sensing surface. The obtained 10{sup 17 }cm{sup −3} nitrogen-vacancy density is only a factor of 10 less than the highest densities reported to date, with an observed 200 kHz spin resonance linewidth over 10 times narrower.

Thin films of amorphous nitrogenated carbon a-CN{sub x}: Electron transfer and surface reactivity

Energy Technology Data Exchange (ETDEWEB)

Tamiasso-Martinhon, P.; Cachet, H.; Debiemme-Chouvy, C.; Deslouis, C. [Universite Pierre et Marie Curie-Paris 6, Laboratoire Interfaces et Systemes Electrochimiques, CNRS, UPR15-LISE, 4 Place Jussieu, Paris F-75005 (France)

2008-08-01

The electrochemical behaviour of thin films of nitrogenated amorphous carbon a-CN{sub x} is similar to that of boron-doped diamond, with a wide potential window in aqueous media. They are elaborated by cathodic sputtering of a graphite target in an Ar-N{sub 2} active plasma for varying nitrogen contents, determined by XPS (0.06 {<=} x {<=} 0.39). Their electrochemical reactivity is sensitive to the surface state. The present study reports on the influence of electrochemical pre treatment on the electronic transfer rate of a fast redox system ferri-ferrocyanide, by focusing on the direction of the potential excursion. On the other hand, the role of both the pH and the potential on the interfacial capacitance in the presence of Na{sub 2}SO{sub 4} without redox species is documented. The results show up the sensitivity of the film surface to the electrochemical conditions. (author)

Automation system for tritium contaminated surface monitoring

International Nuclear Information System (INIS)

Culcer, Mihai; Iliescu, Mariana; Curuia, Marian; Raceanu, Mircea; Enache, Adrian; Stefanescu, Ioan; Ducu, Catalin; Malinovschi, Viorel

2005-01-01

The low energy of betas makes tritium difficult to detect. However, there are several methods used in tritium detection, such as liquid scintillation and ionization chambers. Tritium on or near a surface can be also detected using proportional counter and, recently, solid state devices. The paper presents our results in the design and achievement of a surface tritium monitor using a PIN photodiode as a solid state charged particle detector to count betas emitted from the surface. That method allows continuous, real-time and non-destructively measuring of tritium. (authors)

Nitrogen patterns in subsurface waters of the Yzeron stream: effect of combined sewer overflows and subsurface-surface water mixing.

Science.gov (United States)

Aucour, A M; Bariac, T; Breil, P; Namour, P; Schmitt, L; Gnouma, R; Zuddas, P

2013-01-01

Urbanization subjects streams to increased nitrogen loads. Therefore studying nitrogen forms at the interface between urban stream and groundwater is important for water resource management. In this study we report results on water δ(18)O and nitrogen forms in subsurface waters of a stream (Yzeron, France). The sites studied were located upstream and downstream of combined sewer overflows (CSO) in a rural area and a periurban area, respectively. Water δ(18)O allowed us to follow the mixing of subsurface water with surface water. Dissolved organic nitrogen and organic carbon of fine sediment increased by 20-30% between rural and periurban subsurface waters in the cold season, under high flow. The highest nitrate levels were observed in rural subsurface waters in the cold season. The lowest nitrate levels were found in periurban subsurface waters in the warm season, under low flow. They corresponded to slow exchange of subsurface waters with channel water. Thus reduced exchange between surface and subsurface waters and organic-matter-rich input seemed to favor nitrate reduction in the downstream, periurban, subsurface waters impacted by CSO.

Bacterial nitrogen fixation in sand bioreactors treating winery wastewater with a high carbon to nitrogen ratio.

Science.gov (United States)

Welz, Pamela J; Ramond, Jean-Baptiste; Braun, Lorenz; Vikram, Surendra; Le Roes-Hill, Marilize

2018-02-01

Heterotrophic bacteria proliferate in organic-rich environments and systems containing sufficient essential nutrients. Nitrogen, phosphorus and potassium are the nutrients required in the highest concentrations. The ratio of carbon to nitrogen is an important consideration for wastewater bioremediation because insufficient nitrogen may result in decreased treatment efficiency. It has been shown that during the treatment of effluent from the pulp and paper industry, bacterial nitrogen fixation can supplement the nitrogen requirements of suspended growth systems. This study was conducted using physicochemical analyses and culture-dependent and -independent techniques to ascertain whether nitrogen-fixing bacteria were selected in biological sand filters used to treat synthetic winery wastewater with a high carbon to nitrogen ratio (193:1). The systems performed well, with the influent COD of 1351 mg/L being reduced by 84-89%. It was shown that the nitrogen fixing bacterial population was influenced by the presence of synthetic winery effluent in the surface layers of the biological sand filters, but not in the deeper layers. It was hypothesised that this was due to the greater availability of atmospheric nitrogen at the surface. The numbers of culture-able nitrogen-fixing bacteria, including presumptive Azotobacter spp. exhibited 1-2 log increases at the surface. The results of this study confirm that nitrogen fixation is an important mechanism to be considered during treatment of high carbon to nitrogen wastewater. If biological treatment systems can be operated to stimulate this phenomenon, it may obviate the need for nitrogen addition. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effects of pretreatment on the surface chemistry and pore size properties of nitrogen functionalized and alkylated granular activated carbon

Energy Technology Data Exchange (ETDEWEB)

Chen Jiajun [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082 (China); Zhai Yunbo, E-mail: ybzhai@hnu.edu.cn [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082 (China); Chen Hongmei; Li Caiting; Zeng Guangming; Pang Daoxiong; Lu Pei [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082 (China)

2012-12-15

Highlights: Black-Right-Pointing-Pointer The effects of pretreatment on the surface chemistry and pore sizes were studied. Black-Right-Pointing-Pointer Treated GAC was nitrogen functionalized and alkylated GAC also called modified GAC. Black-Right-Pointing-Pointer HNO{sub 3} pretreatment caused a slight decrease in surface area and microporosity. Black-Right-Pointing-Pointer The nitrogen percentage of modified GAC which pretreated by H{sub 2}O{sub 2} was 4.07%. Black-Right-Pointing-Pointer The pyridine of modified GAC which pretreated by urea-formaldehyde resin was 45.88%. - Abstract: In this paper, granular activated carbon (GAC) from coconut shell was pretreated by HNO{sub 3}, H{sub 2}O{sub 2} and urea-formaldehyde resin, respectively. Then the obtained materials were functionalized in the same way for nitrogen group, and then alkylated. Effects of pretreatment on the surface chemistry and pore size of modified GACs were studied. Surface area and micropore volume of modified GAC which pretreated by HNO{sub 3} were 723.88 m{sup 2}/g and 0.229 cm{sup 3}/g, respectively, while virgin GAC were 742.34 m{sup 2}/g and 0.276 cm{sup 3}/g. Surface area and micropore volume decrease of the modified GACs which pretreated by the others two methods were more drastically. The types of groups presented were analyzed by electrophoresis, Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). N-CH{sub 3} group and C=N group were detected on the surfaces of these three kinds of modified GACs. Results of XPS showed that the nitrogen functions of modified GAC which pretreated by H{sub 2}O{sub 2} was 4.07%, it was more than that of the others two pretreatment methods. However, the modified GAC which pretreated by urea-formaldehyde resin was fixed more pyridine structure, which structure percentage was 45.88%, in addition, there were more basic groups or charge on the surface than the others.

Recent studies of the ocean nitrogen cycle

Science.gov (United States)

Eppley, R. W.

1984-01-01

The nitrogen cycle in the ocean is dominated by the activities of organisms. External nitrogen inputs from land and from the atmosphere are small compared with rates of consumption and production by organisms and with rates of internal rearrangements of nitrogen pools within the ocean. The chief reservoirs of nitrogen are, in decreasing order of size: nitrogen in sediments, dissolved N2, nitrate, dissolved organic nitrogen (DON), particulate organic nitrogen (PON) (mostly organisms and their by-products). The biogenic fluxes of nitrogen were reviewed. The rate of PON decomposition in the surface layer must be comparable to the rate of ammonium consumption; and at the same time the nitrate consumption rate will be similar to the rates of: (1) sinking of PON out of the surface layer and its decompositon at depth, (2) the rate of nitrification at depth, and (3) the rate of nitrate return to the surface layer by upwelling.

Nitrogen multitemporal monitoring through mosses in urban areas affected by mud volcanoes around Mt. Etna, Italy.

Science.gov (United States)

Bonanno, Giuseppe

2013-10-01

Nitrogen emissions were assessed by using mosses as bioindicators in a densely inhabited area affected by mud volcanoes. Such volcanoes, locally called Salinelle, are phenomena that occur around Mt. Etna (Sicily, Italy), and are interpreted as the surface outflow of a hydrothermal system located below Mt. Etna, which releases sedimentary fluids (hydrocarbons and Na-Cl brines) along with magmatic gases (mainly CO2 and He). To date, N emissions from such mud volcanoes have been only quantitatively assessed, and no biomonitoring campaigns are reported about the cumulative effects of these emissions. This study analyzed N concentrations in moss, water and soil samples, collected in a 4-year monitoring campaign. The bryophyte Bryum argenteum, a species widely adopted in surveys of atmospheric pollution, was used as a biological indicator. N concentrations in biomonitors showed relatively low values in the study sites. However, the results of this study suggest that N emissions from Salinelle may have an impact on surrounding ecosystems because N values in moss and water showed a significant correlation. N oxides, in particular, contribute to acidification of ecosystems, thus multitemporal biomonitoring is recommended, especially in those areas where N emitting sources are anthropogenic and natural.

Characteristics of Nitrogen Loss through Surface-Subsurface Flow on Red Soil Slopes of Southeast China

Science.gov (United States)

Zheng, Haijin; Liu, Zhao; Zuo, Jichao; Wang, Lingyun; Nie, Xiaofei

2017-12-01

Soil nitrogen (N) loss related to surface flow and subsurface flow (including interflow and groundwater flow) from slope lands is a global issue. A lysimetric experiment with three types of land cover (grass cover, GC; litter cover, LC; and bare land, BL) were carried out on a red soil slope land in southeast China. Total Nitrogen (TN) loss through surface flow, interflow and groundwater flow was observed under 28 natural precipitation events from 2015 to 2016. TN concentrations from subsurface flow on BL and LC plots were, on average, 2.7-8.2 and 1.5-4.4 times greater than TN concentrations from surface flow, respectively; the average concentration of TN from subsurface flow on GC was about 36-56% of that recorded from surface flow. Surface flow, interflow and groundwater flow contributed 0-15, 2-9 and 76-96%, respectively, of loss load of TN. Compared with BL, GC and LC intercepted 83-86% of TN loss through surface runoff; GC intercepted 95% of TN loss through subsurface flow while TN loss through subsurface flow on LC is 2.3 times larger than that on BL. In conclusion, subsurface flow especially groundwater flow is the dominant hydrological rout for N loss that is usually underestimated. Grass cover has the high retention of N runoff loss while litter mulch will increase N leaching loss. These findings provide scientific support to control N runoff loss from the red soil slope lands by using suitable vegetation cover and mulching techniques.

Calorimetry by immersion into liquid nitrogen and liquid argon: a better way to determine the internal surface area of micropores.

Science.gov (United States)

Navarrete, Ricardo; Llewellyn, Philip; Rouquerol, Françoise; Denoyel, Renaud; Rouquerol, Jean

2004-09-15

The aim of this work is to assess the internal surface area of a set of samples (either carbons or oxides, either porous or nonporous, either microporous or mesoporous) by microcalorimetry via immersion into liquid nitrogen or argon. We have made use of an isothermal, heat-flux microcalorimeter, initially designed and built in our laboratory for the sake of gas adsorption experiments at 77 or 87 K. It seems that immersion calorimetry into liquid nitrogen and argon makes it possible to go one step further in the determination of the internal surface area of micropores.

Study of the temperature dependent nitrogen retention in tungsten surfaces by XPS-analysis

Energy Technology Data Exchange (ETDEWEB)

Plank, Ulrike [Max-Planck-Institut fuer Plasmaphysik, Boltzmannstr. 2, D-85748 Garching (Germany); Fakultaet fuer Physik der Ludwig-Maximilians-Universitaet Muenchen, Schellingstrasse 4, D-80799 Muenchen (Germany); Meisl, Gerd; Hoeschen, Till [Max-Planck-Institut fuer Plasmaphysik, Boltzmannstr. 2, D-85748 Garching (Germany)

2016-07-01

To reduce the power load on the divertor of fusion experiments, nitrogen (N) is puffed into the plasma. As a side effect, nitrogen gets implanted into the tungsten (W) walls of the reactor and forms nitride layers. Their formation and, therefore, the N accumulation in W showed an unexpected temperature dependence in previous experiments. To study the nitrogen retention, we implanted N ions with an energy of 300 eV into W and observed the evolution of the surface composition by X-ray photoelectron spectroscopy (XPS). We find that the N content does not change when the sample is annealed up to 800 K after implantation at lower temperatures. In contrast, the N concentration decreases with increasing implantation temperature. At 800 K implantation temperature, the N saturation level is about 5 times lower compared to 300 K implantation. A possible explanation for this difference is an enhanced diffusion during ion bombardment due to changes in the structure or in the chemical state of the tungsten nitride system. Ongoing tungsten nitride erosion experiments shall help to clarify whether the strong temperature dependence is the result of enhanced diffusion or of phase changes.

Nitrogen fate and Transport in Diverse Agricultural Watersheds

Science.gov (United States)

Essaid, H.; McCarthy, K. A.; Baker, N. T.

2010-12-01

Nitrogen mass budgets have been estimated for ten agricultural watersheds located in a range of hydrologic settings in order to understand the factors controlling the fate of nitrogen applied at the surface. The watersheds, study areas of the Agricultural Chemical Sources, Transport and Fate study of the U.S. Geological Survey National Water Quality Assessment Program, are located in Indiana (IN), Iowa (IA), Maryland (MD), Nebraska (NE), Mississippi (MS) and Washington (WA). They range in size from 7 to 1254 km2, with four of the watersheds nested within larger watersheds. Surface water outflow (normalized to watershed area) ranged from 4 to 83 cm/yr. Crops planted include corn, soybean, small grains, rice, cotton, orchards and vegetables. “Surplus nitrogen” was determined for each watershed by subtracting estimates of crop uptake and volatilization from estimates of nitrogen input from atmospheric deposition, plant fixation, and fertilizer and manure applications for the period from 1987 to 2004. This surplus nitrogen is transported though the watershed via surface and subsurface flow paths, while simultaneously undergoing transformations (such as denitrification and in-stream processing) that result in less export of nitrogen from the watershed. Surface-water discharge and concentration data were used to estimate the export of nitrogen from the watersheds (groundwater outflow from the watersheds was minimal). Subtracting nitrogen export from surplus nitrogen provides an estimate of the net amount of nitrogen removal occurring during internal watershed transport. Watershed average nitrogen surplus ranged from 6 to 49 kg-N/ha. The more permeable and/or greater water flux watersheds (MD, NE, and WA) tended to have larger surplus nitrogen, possibly due to less crop uptake caused by greater leaching and runoff of nitrogen. Almost all of the surplus nitrogen in the low permeability (MS) and tile drained watersheds (IA, IN) was exported from the watershed with

Monitoring and modelling of biosphere/atmosphere exchange of gases and aerosols in Europe

Energy Technology Data Exchange (ETDEWEB)

Erisman, Jan Willem [Energy Research Centre of the Netherlands (ECN), P.O. Box 1, 1755 ZG Petten (Netherlands)]. E-mail: erisman@ecn.nl; Vermeulen, Alex [Energy Research Centre of the Netherlands (ECN), P.O. Box 1, 1755 ZG Petten (Netherlands); Hensen, Arjan [Energy Research Centre of the Netherlands (ECN), P.O. Box 1, 1755 ZG Petten (Netherlands); Flechard, Chris [Energy Research Centre of the Netherlands (ECN), P.O. Box 1, 1755 ZG Petten (Netherlands); Daemmgen, Ulrich [Federal Agricultural Research Centre, Institute of Agroecology, D-38116 Braunschweig, (Germany); Fowler, David [CEH, Bush Estate, Penicuik, Midlothian EH26 0QB (United Kingdom); Sutton, Mark [CEH, Bush Estate, Penicuik, Midlothian EH26 0QB (United Kingdom); Gruenhage, Ludger [Institute for Plant Ecology, Justus-Liebig-University, D-35392 Giessen (Germany); Tuovinen, Juha-Pekka [Finnish Meteorological Institute, FIN-00810 Helsinki (Finland)

2005-02-01

Monitoring and modelling of deposition of air pollutants is essential to develop and evaluate policies to abate the effects related to air pollution and to determine the losses of pollutants from the atmosphere. Techniques for monitoring wet deposition fluxes are widely applied. A recent intercomparison experiment, however, showed that the uncertainty in wet deposition is relatively high, up to 40%, apart from the fact that most samplers are biased because of a dry deposition contribution. Wet deposition amounts to about 80% of the total deposition in Europe with a range of 10-90% and uncertainty should therefore be decreased. During recent years the monitoring of dry deposition has become possible. Three sites have been operational for 5 years. The data are useful for model development, but also for model evaluation and monitoring of progress in policy. Data show a decline in SO{sub 2} dry deposition, whereas nitrogen deposition remained constant. Furthermore, surface affinities for pollutants changed leading to changes in deposition. Deposition models have been further developed and tested with dry deposition measurements and total deposition measurements on forests as derived from throughfall data. The comparison is reasonable given the measurement uncertainties. Progress in ozone surface exchange modelling and monitoring shows that stomatal uptake can be quantified with reasonable accuracy, but external surface uptake yields highest uncertainty. - Monitoring and modelling of the deposition of sulphur and nitrogen components and the exposure of ozone has gained much progress through the research within BIATEX.

Estimated anthropogenic nitrogen and phosphorus inputs to the land surface of the conterminous United States--1992, 1997, and 2002

Science.gov (United States)

Sprague, Lori A.; Gronberg, Jo Ann M.

2013-01-01

Anthropogenic inputs of nitrogen and phosphorus to each county in the conterminous United States and to the watersheds of 495 surface-water sites studied as part of the U.S. Geological Survey National Water-Quality Assessment Program were quantified for the years 1992, 1997, and 2002. Estimates of inputs of nitrogen and phosphorus from biological fixation by crops (for nitrogen only), human consumption, crop production for human consumption, animal production for human consumption, animal consumption, and crop production for animal consumption for each county are provided in a tabular dataset. These county-level estimates were allocated to the watersheds of the surface-water sites to estimate watershed-level inputs from the same sources; these estimates also are provided in a tabular dataset, together with calculated estimates of net import of food and net import of feed and previously published estimates of inputs from atmospheric deposition, fertilizer, and recoverable manure. The previously published inputs are provided for each watershed so that final estimates of total anthropogenic nutrient inputs could be calculated. Estimates of total anthropogenic inputs are presented together with previously published estimates of riverine loads of total nitrogen and total phosphorus for reference.

Influence of nitrogen surface functionalities on the catalytic activity of activated carbon in low temperature SCR of NO{sub x} with NH{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Szymanski, Grzegorz S. [Faculty of Chemistry, Nicolaus Copernicus University, Gagarina 7, 87-100 Torun (Poland); Grzybek, Teresa [Faculty of Fuels and Energy, AGH, University of Science and Technology, Al. Mickiewicza 30, 30-059 Krakow (Poland); Papp, Helmut [Faculty of Chemistry and Mineralogy, Institute of Technical Chemistry, University of Leipzig, Linnerstrasse 3, 04103 Leipzig (Germany)

2004-06-15

The reduction of nitrogen oxide with ammonia was studied using carbon catalysts with chemically modified surfaces. Carbon samples with different surface chemistry were obtained from commercial activated carbon D43/1 (CarboTech, Essen, Germany) by chemical modification involving oxidation with conc. nitric acid (DOx) (1); high temperature treatment (=1000K) under vacuum (DHT) (2); or in ammonia (DHTN, DOxN) (3). Additionally, a portion of the DOx sample was promoted with iron(III) ions (DOxFe). The catalytic tests were performed in a microreactor at a temperature range of 413-573K. The carbon sample annealed under vacuum (DHT) showed the lowest activity. The formation of surface acidic surface oxides by nitric acid treatment (DOx) enhanced the catalytic activity only slightly. However, as can be expected, subsequent promotion of the DOx sample with iron(III) ions increased drastically its catalytic activity. However, this was accompanied by some loss of selectivity, i.e. formation of N{sub 2}O as side product. This effect can be avoided using ammonia-treated carbons which demonstrated reasonable activity with simultaneous high selectivity. The most active and selective among them was the sample that was first oxidized with nitric acid and then heated in an ammonia stream (DOxN). A correlation between catalytic activity and surface nitrogen content was observed. Surface nitrogen species seem to play an important role in catalytic selective reduction of nitrogen oxide with ammonia, possibly facilitating NO{sub 2} formation (a reaction intermediate) as a result of easier chemisorption of oxygen and nitrogen oxide.

Heat and mass transfer of liquid nitrogen in coal porous media

Science.gov (United States)

Lang, Lu; Chengyun, Xin; Xinyu, Liu

2018-04-01

Liquid nitrogen has been working as an important medium in fire extinguishing and prevention, due to its efficiency in oxygen exclusion and heat removal. Such a technique is especially crucial for coal industry in China. We built a tunnel model with a temperature monitor system (with 36 thermocouples installed) to experimentally study heat and mass transfer of liquid nitrogen in non-homogeneous coal porous media (CPM), and expected to optimize parameters of liquid nitrogen injection in engineering applications. Results indicate that injection location and amount of liquid nitrogen, together with air leakage, significantly affect temperature distribution in CPM, and non-equilibrium heat inside and outside of coal particles. The injection position of liquid nitrogen determines locations of the lowest CPM temperature and liquid nitrogen residual. In the deeper coal bed, coal particles take longer time to reach thermal equilibrium between their surface and inside. Air leakage accelerates temperature increase at the bottom of the coal bed, which is a major reason leading to fire prevention inefficiency. Measurement fluctuation of CPM temperature may be caused by incomplete contact of coal particles with liquid nitrogen flowing in the coal bed. Moreover, the secondary temperature drop (STD) happens and grows with the more injection of liquid nitrogen, and the STD phenomenon is explained through temperature distributions at different locations.

High-Surface-Area Nitrogen-Doped Reduced Graphene Oxide for Electric Double-Layer Capacitors.

Science.gov (United States)

Youn, Hee-Chang; Bak, Seong-Min; Kim, Myeong-Seong; Jaye, Cherno; Fischer, Daniel A; Lee, Chang-Wook; Yang, Xiao-Qing; Roh, Kwang Chul; Kim, Kwang-Bum

2015-06-08

A two-step method consisting of solid-state microwave irradiation and heat treatment under NH3 gas was used to prepare nitrogen-doped reduced graphene oxide (N-RGO) with a high specific surface area (1007 m(2)  g(-1) ), high electrical conductivity (1532 S m(-1) ), and low oxygen content (1.5 wt %) for electrical double-layer capacitor applications. The specific capacitance of N-RGO was 291 F g(-1) at a current density of 1 A g(-1) , and a capacitance of 261 F g(-1) was retained at 50 A g(-1) , which indicated a very good rate capability. N-RGO also showed excellent cycling stability and preserved 96 % of the initial specific capacitance after 100 000 cycles. Near-edge X-ray absorption fine-structure spectroscopy results provided evidenced for the recovery of π conjugation in the carbon networks with the removal of oxygenated groups and revealed chemical bonding of the nitrogen atoms in N-RGO. The good electrochemical performance of N-RGO is attributed to its high surface area, high electrical conductivity, and low oxygen content. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Position-sensitive radiation monitoring (surface contamination monitor). Innovative technology summary report

International Nuclear Information System (INIS)

1999-06-01

The Shonka Research Associates, Inc. Position-Sensitive Radiation Monitor both detects surface radiation and prepares electronic survey map/survey report of surveyed area automatically. The electronically recorded map can be downloaded to a personal computer for review and a map/report can be generated for inclusion in work packages. Switching from beta-gamma detection to alpha detection is relatively simple and entails moving a switch position to alpha and adjusting the voltage level to an alpha detection level. No field calibration is required when switching from beta-gamma to alpha detection. The system can be used for free-release surveys because it meets the federal detection level sensitivity limits requires for surface survey instrumentation. This technology is superior to traditionally-used floor contamination monitor (FCM) and hand-held survey instrumentation because it can precisely register locations of radioactivity and accurately correlate contamination levels to specific locations. Additionally, it can collect and store continuous radiological data in database format, which can be used to produce real-time imagery as well as automated graphics of survey data. Its flexible design can accommodate a variety of detectors. The cost of the innovative technology is 13% to 57% lower than traditional methods. This technology is suited for radiological surveys of flat surfaces at US Department of Energy (DOE) nuclear facility decontamination and decommissioning (D and D) sites or similar public or commercial sites

Position-sensitive radiation monitoring (surface contamination monitor). Innovative technology summary report

Energy Technology Data Exchange (ETDEWEB)

1999-06-01

The Shonka Research Associates, Inc. Position-Sensitive Radiation Monitor both detects surface radiation and prepares electronic survey map/survey report of surveyed area automatically. The electronically recorded map can be downloaded to a personal computer for review and a map/report can be generated for inclusion in work packages. Switching from beta-gamma detection to alpha detection is relatively simple and entails moving a switch position to alpha and adjusting the voltage level to an alpha detection level. No field calibration is required when switching from beta-gamma to alpha detection. The system can be used for free-release surveys because it meets the federal detection level sensitivity limits requires for surface survey instrumentation. This technology is superior to traditionally-used floor contamination monitor (FCM) and hand-held survey instrumentation because it can precisely register locations of radioactivity and accurately correlate contamination levels to specific locations. Additionally, it can collect and store continuous radiological data in database format, which can be used to produce real-time imagery as well as automated graphics of survey data. Its flexible design can accommodate a variety of detectors. The cost of the innovative technology is 13% to 57% lower than traditional methods. This technology is suited for radiological surveys of flat surfaces at US Department of Energy (DOE) nuclear facility decontamination and decommissioning (D and D) sites or similar public or commercial sites.

Nitrogen trading tool

Science.gov (United States)

The nitrogen cycle is impacted by human activities, including those that increase the use of nitrogen in agricultural systems, and this impact can be seen in effects such as increased nitrate (NO3) levels in groundwater or surface water resources, increased concentration of nitrous oxide (N2O) in th...

Efficiency of nitrogen fertilizers for rice

OpenAIRE

Roger, Pierre-Armand; Grant, I.F.; Reddy, P.M.; Watanabe, I.

1987-01-01

The photosynthetic biomass that develops in the floodwater of wetland rice fields affects nitrogen dynamics in the ecosystem. This review summarizes available data on the nature, productivity, and composition of the photosynthetic aquatic biomass, and its major activities regarding the nitrogen cycle, i.e., nitrogen fixation by free living blue-green algae and #Azolla$, nitrogen trapping, nitrogen accumulation at the soil surface, its effect on nitrogen losses by ammonia volatilization, nitro...

Nitrogen-Doped Carbonaceous Materials for Removal of Phenol from Aqueous Solutions

Directory of Open Access Journals (Sweden)

Magdalena Hofman

2012-01-01

Full Text Available Carbonaceous material (brown coal modified by pyrolysis, activation, and enrichment in nitrogen, with two different factor reagents, have been used as adsorbent of phenol from liquid phase. Changes in the phenol content in the test solutions were monitored after subsequent intervals of adsorption with selected adsorbents prepared from organic materials. Significant effect of nitrogen present in the adsorbent material on its adsorption capacity was noted. Sorption capacity of these selected materials was found to depend on the time of use, their surface area, and pore distribution. A conformation to the most well-known adsorption isotherm models, Langmuir, and Freundlich ones, confirms the formation of mono- and heterolayer solute (phenol coverage on the surface of the adsorbent applied herein. The materials proposed as adsorbents of the aqueous solution contaminants were proved effective, which means that the waste materials considered are promising activated carbon precursors for liquid phase adsorbents for the environmental protection.

Preparation of nitrogen-doped cotton stalk microporous activated carbon fiber electrodes with different surface area from hexamethylenetetramine-modified cotton stalk for electrochemical degradation of methylene blue

Directory of Open Access Journals (Sweden)

Kunquan Li

Full Text Available Cotton-stalk activated carbon fibers (CSCFs with controllable micropore area and nitrogen content were prepared as an efficient electrode from hexamethylenetetramine-modified cotton stalk by steam/ammonia activation. The influence of microporous area, nitrogen content, voltage and initial concentration on the electrical degradation efficiency of methylene blue (MB was evaluated by using CSCFs as anode. Results showed that the CSCF electrodes exhibited excellent MB electrochemical degradation ability including decolorization and COD removal. Increasing micropore surface area and nitrogen content of CSCF anode leaded to a corresponding increase in MB removal. The prepared CSCF-800-15-N, which has highest N content but lowest microporous area, attained the best degradation effect with 97% MB decolorization ratio for 5 mg/L MB at 12 V in 4 h, implying the doped nitrogen played a prominent role in improving the electrochemical degradation ability. The electrical degradation reaction was well described by first-order kinetics model. Overall, the aforesaid findings suggested that the nitrogen-doped CSCFs were potential electrode materials, and their electrical degradation abilities could be effectively enhanced by controlling the nitrogen content and micropore surface area. Keywords: Cotton stalk, Nitrogen content, Electrode, Surface area, Methylene blue

Application for vibration monitoring of aspheric surface machining based on wireless sensor networks

Science.gov (United States)

Han, Chun Guang; Guo, Yin Biao; Jiang, Chen

2010-05-01

Any kinds of tiny vibration of machine tool parts will have a great influence on surface quality of the workpiece at ultra-precise machining process of aspheric surface. At present the major way for decreasing influence of vibration is machining compensation technology. Therefore it is important for machining compensation control to acquire and transmit these vibration signals effectively. This paper presents a vibration monitoring system of aspheric surface machining machine tool based on wireless sensor networks (WSN). Some key issues of wireless sensor networks for vibration monitoring system of aspheric surface machining are discussed. The reliability of data transmission, network communication protocol and synchronization mechanism of wireless sensor networks are studied for the vibration monitoring system. The proposed system achieves multi-sensors vibration monitoring involving the grinding wheel, the workpiece and the workbench spindle. The wireless transmission of vibration signals is achieved by the combination with vibration sensor nodes and wireless network. In this paper, these vibration sensor nodes are developed. An experimental platform is structured which employs wireless sensor networks to the vibration monitoring system in order to test acquisition and wireless transmission of vibration signal. The test results show that the proposed system can achieve vibration data transmission effectively and reliability and meet the monitoring requirements of aspheric surface machining machine tool.

Monitoring tablet surface roughness during the film coating process

DEFF Research Database (Denmark)

Seitavuopio, Paulus; Heinämäki, Jyrki; Rantanen, Jukka

2006-01-01

The purpose of this study was to evaluate the change of surface roughness and the development of the film during the film coating process using laser profilometer roughness measurements, SEM imaging, and energy dispersive X-ray (EDX) analysis. Surface roughness and texture changes developing during...... the process of film coating tablets were studied by noncontact laser profilometry and scanning electron microscopy (SEM). An EDX analysis was used to monitor the magnesium stearate and titanium dioxide of the tablets. The tablet cores were film coated with aqueous hydroxypropyl methylcellulose, and the film...... coating was performed using an instrumented pilot-scale side-vented drum coater. The SEM images of the film-coated tablets showed that within the first 30 minutes, the surface of the tablet cores was completely covered with a thin film. The magnesium signal that was monitored by SEM-EDX disappeared after...

Nitrogen-doped ordered mesoporous carbon with a high surface area, synthesized through organic-inorganic coassembly, and its application in supercapacitors.

Science.gov (United States)

Song, Yanfang; Li, Li; Wang, Yonggang; Wang, Congxiao; Guo, Zaipin; Xia, Yongyao

2014-07-21

A new nitrogen-doped ordered mesoporous carbon (N-doped OMC) is synthesized by using an organic-inorganic coassembly method, in which resol is used as the carbon precursor, dicyandiamide as the nitrogen precursor, silicate oligomers as the inorganic precursors, and F127 as the soft template. The N-doped OMC possesses a surface area as high as 1374 m(2)  g(-1) and a large pore size of 7.4 nm. As an electrode material for supercapacitors, the obtained carbon exhibits excellent cycling stability and delivers a reversible specific capacitance as high as 308 F g(-1) in 1 mol L(-1) H(2)SO(4) aqueous electrolyte, of which 58 % of the capacity is due to pseudo-capacitance. The large specific capacitance is attributed to proper pore size distributions, large surface area, and high nitrogen content. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nitrogen and Oxygen Isotopic Studies of the Marine Nitrogen Cycle.

Science.gov (United States)

Casciotti, Karen L

2016-01-01

The marine nitrogen cycle is a complex web of microbially mediated reactions that control the inventory, distribution, and speciation of nitrogen in the marine environment. Because nitrogen is a major nutrient that is required by all life, its availability can control biological productivity and ecosystem structure in both surface and deep-ocean communities. Stable isotopes of nitrogen and oxygen in nitrate and nitrite have provided new insights into the rates and distributions of marine nitrogen cycle processes, especially when analyzed in combination with numerical simulations of ocean circulation and biogeochemistry. This review highlights the insights gained from dual-isotope studies applied at regional to global scales and their incorporation into oceanic biogeochemical models. These studies represent significant new advances in the use of isotopic measurements to understand the modern nitrogen cycle, with implications for the study of past ocean productivity, oxygenation, and nutrient status.

Substitutional Nitrogen in Nanodiamond and Bucky-Diamond Particles

Energy Technology Data Exchange (ETDEWEB)

Barnard, Amanda S.; Sternberg, Michael G.

2005-09-15

The inclusion of dopants (such as nitrogen) in diamond nanoparticles is expected to be important for use in future nanodevices, such as qubits for quantum computing. Although most commercial diamond nanoparticles contain a small fraction of nitrogen, it is still unclear whether it is located within the core or at the surface of the nanoparticle. Presented here are density functional tight binding simulations examining the configuration, potential energy surface, and electronic charge of substitutional nitrogen in nanodiamond and bucky-diamond particles. The results predict that nitrogen is likely to be positioned at the surface of both hydrogenated nanodiamond and (dehydrogenated) bucky-diamond, and that the coordination of the dopants within the particles is dependent upon the surface structure.

Surface acoustic wave dust deposition monitor

Science.gov (United States)

Fasching, G.E.; Smith, N.S. Jr.

1988-02-12

A system is disclosed for using the attenuation of surface acoustic waves to monitor real time dust deposition rates on surfaces. The system includes a signal generator, a tone-burst generator/amplifier connected to a transmitting transducer for converting electrical signals into acoustic waves. These waves are transmitted through a path defining means adjacent to a layer of dust and then, in turn, transmitted to a receiving transducer for changing the attenuated acoustic wave to electrical signals. The signals representing the attenuated acoustic waves may be amplified and used in a means for analyzing the output signals to produce an output indicative of the dust deposition rates and/or values of dust in the layer. 8 figs.

Monitoring of tritium-contaminated surfaces, including skin

International Nuclear Information System (INIS)

Surette, R.A.; Wood, M.J.

1994-05-01

We have examined various commercially available tritium surface contamination monitors along with different swipe media and techniques for direct and indirect (swipe) monitoring of contaminated surfaces, including skin. None of the methods or instruments evaluated were more sensitive than the swipe and liquid scintillation counting (LSC) method. Swipe measurements with open-window proportional counters were, in general, less than half as sensitive as LSC, but have the advantages of having the results available almost immediately, and no sample preparation is required. The Nuclear Measurement Corporation's PC-55 is the most suitable instrument we tested for the analysis of routine swipe measurement. The PC-55 was about one third as sensitive as LSC when used with Ontario Hydro filter paper swipe media. Surface contamination measurement results can be obtained within minutes using the PC-55, compared to hours using LSC. The selection of swipe media for use with proportional counter-based instruments is critical. A medium that is electrically insulating can develop an electrostatic charge on its surface; this may alter the field gradient in the detector and may adversely influence the results. Although the PC-55 is sufficiently sensitive and very convenient, operational experience with the instrument is needed before recommending that it replace current LSC methods. The PC-55's susceptibility to internal tritium contamination may limit its practical usefulness. Because of the complexity of using live animals to evaluate direct and indirect methods for assessing skin contamination, pig skin was investigated as a possible substitute. We concluded that, for the first few hours post-exposure, pig skin mimics the kinetics of animal skin that has contacted a tritium-contaminated surface. (author). 30 refs., 1 tab., 7 figs

Modelling land surface fluxes of CO2 in response to climate change and nitrogen deposition

DEFF Research Database (Denmark)

Hansen, Kristina; Ambelas Skjøth, Carsten; Geels, Camilla

Climate change, land use variations, and impacts of atmospheric nitrogen (N) deposition represent uncertainties for the prediction of future greenhouse gas exchange between land surfaces and the atmosphere as the mechanisms describing nutritional effects are not well developed in climate...... climate feedback mechanisms of CO2 between changes in management, land use practise, and climate change....

NEC Hazardous classification and compliance regarding the surface moisture monitor measurement system

International Nuclear Information System (INIS)

Bussell, J.H.

1996-01-01

The National Electrical Code, NFPA 70, and National Fire Protection Association requirements for use of Surface Moisture Monitor Systems in classified locations are discussed. The design and configuration of the surface moisture monitor are analyzed with respect to how they comply with requirements of the National Electrical Code requirements, articles 500-504

A compendium of results from long-range alpha detector soil surface monitoring: June 1992--May 1994

International Nuclear Information System (INIS)

Garner, S.E.; Bounds, J.A.; Allander, K.S.; Johnson, J.D.; MacArthur, D.W.; Caress, R.W.

1994-11-01

Soil surface monitors based on long-range alpha detector (LRAD) technology are being used to monitor alpha contamination at various sites in the Department of Energy complex. These monitors, the large soil-surface monitor (LSSM) and the small soil-surface monitor (SSSM), were used to help characterize sites at Fernald, Ohio, and active or inactive firing sites at Sandia National Laboratories and Los Alamos National Laboratory. Monitoring results are presented herein in chronological order

Monitoring the Vadose Zone Moisture Regime Below a Surface Barrier

Science.gov (United States)

Zhang, Z. F.; Strickland, C. E.; Field, J. G.

2009-12-01

A 6000 m2 interim surface barrier has been constructed over a portion of the T Tank Farm in the Depart of Energy’s Hanford site. The purpose of using a surface barrier was to reduce or eliminate the infiltration of meteoric precipitation into the contaminated soil zone due to past leaks from Tank T-106 and hence to reduce the rate of movement of the plume. As part of the demonstration effort, vadose zone moisture is being monitored to assess the effectiveness of the barrier on the reduction of soil moisture flow. A vadose zone monitoring system was installed to measure soil water conditions at four horizontal locations (i.e., instrument Nests A, B, C, and D) outside, near the edge of, and beneath the barrier. Each instrument nest consists of a capacitance probe with multiple sensors, multiple heat-dissipation units, and a neutron probe access tube used to measure soil-water content and soil-water pressure. Nest A serves as a control by providing subsurface conditions outside the influence of the surface barrier. Nest B provides subsurface measurements to assess barrier edge effects. Nests C and D are used to assess the impact of the surface barrier on soil-moisture conditions beneath it. Monitoring began in September 2006 and continues to the present. To date, the monitoring system has provided high-quality data. Results show that the soil beneath the barrier has been draining from the shallower depth. The lack of climate-caused seasonal variation of soil water condition beneath the barrier indicates that the surface barrier has minimized water exchange between the soil and the atmosphere.

Spectral Indices to Monitor Nitrogen-Driven Carbon Uptake in Field Corn

Science.gov (United States)

Corp, Lawrence A.; Middleton, Elizabeth M.; Campbell, Peya E.; Huemmrich, K. Fred; Daughtry, Craig S. T.; Russ, Andrew; Cheng, Yen-Ben

2010-01-01

Climate change is heavily impacted by changing vegetation cover and productivity with large scale monitoring of vegetation only possible with remote sensing techniques. The goal of this effort was to evaluate existing reflectance (R) spectroscopic methods for determining vegetation parameters related to photosynthetic function and carbon (C) dynamics in plants. Since nitrogen (N) is a key constituent of photosynthetic pigments and C fixing enzymes, biological C sequestration is regulated in part by N availability. Spectral R information was obtained from field corn grown at four N application rates (0, 70, 140, 280 kg N/ha). A hierarchy of spectral observations were obtained: leaf and canopy with a spectral radiometer; aircraft with the AISA sensor; and satellite with EO-1 Hyperion. A number of spectral R indices were calculated from these hyperspectral observations and compared to geo-located biophysical measures of plant growth and physiological condition. Top performing indices included the R derivative index D730/D705 and the normalized difference of R750 vs. R705 (ND705), both of which differentiated three of the four N fertilization rates at multiple observation levels and yielded high correlations to these carbon parameters: light use efficiency (LUE); C:N ratio; and crop grain yield. These results advocate the use of hyperspectral sensors for remotely monitoring carbon cycle dynamics in managed terrestrial ecosystems.

Nitrogen-doped Carbon Microfiber with Wrinkled Surface for High Performance Supercapacitors

Science.gov (United States)

Liu, Ruili; Pan, Lixia; Jiang, Jianzhong; Xi, Xin; Liu, Xiaoxue; Wu, Dongqing

2016-02-01

In this work, nitrogen-doped carbon microfiber (NCMF) is fabricated via a facile co-assembly of natural silk and graphene oxide (GO) and the following thermal treatment. The amphiphilic nature of GO endows NCMF a crumpled surface with a high surface area of 115 m2 g-1. As the binder-free electrode in electrical double-layer capacitors, NCMF shows an excellent capacitance of 196 F g-1 at scan rate of 5 mV s-1, which is almost four times higher than that of the pristine CMF from silk (55 F g-1). Additionally, the capacitance of NCMF can be kept around 92 F g-1 at a high scan rate of 300 mV s-1 even after 10000 cycles. More importantly, a high energy density (≈22.7 μW h cm-2) and power density (≈10.26 mW cm-2) are achieved by the all-solid-state supercapacitor based on NCMF.

Measurements of nitrogen depth distribution in the surface of steel with the 14N(d,p0)15N reaction

International Nuclear Information System (INIS)

Didriksson, R.; Goenczi, L.; Sundqvist, B.

1980-01-01

The 14 N(d,p 0 ) 15 N nuclear reaction has been used to measure the nitrogen depth distribution in the surface of steel samples. With a beam energy of 2.5 MeV a depth of 15μm could be analyzed. The depth resolution was 0.7 μm (FWHM) and nitrogen contents down to 0.02 percent could be determined. (author)

Mechanism of nitrogen removal in wastewater lagoon: a case study.

Science.gov (United States)

Vendramelli, Richard A; Vijay, Saloni; Yuan, Qiuyan

2017-06-01

Ammonia being a nutrient facilitates the growth of algae in wastewater and causes eutrophication. Nitrate poses health risk if it is present in drinking water. Hence, nitrogen removal from wastewater is required. Lagoon wastewater treatment systems have become common in Canada these days. The study was conducted to understand the nitrogen removal mechanisms from the existing wastewater treatment lagoon system in the town of Lorette, Manitoba. The lagoon system consists of two primary aerated cells and two secondary unaerated cells. Surface samples were collected periodically from lagoon cells and analysed from 5 May 2015 to 9 November 2015. The windward and leeward sides of the ponds were sampled and the results were averaged. It was found that the free ammonia volatilization to the atmosphere is responsible for most of the ammonia removal. Ammonia and nitrate assimilation into biomass and biological growth in the cells appears to be the other mechanisms of nitrogen removal over the monitoring period. Factors affecting the nitrogen removal efficiency were found to be pH, temperature and hydraulic residence time. Also, the ammonia concentration in the effluent from the wastewater treatment lagoon was compared with the regulatory standard.

Surface Acoustic Wave Monitor for Deposition and Analysis of Ultra-Thin Films

Science.gov (United States)

Hines, Jacqueline H. (Inventor)

2015-01-01

A surface acoustic wave (SAW) based thin film deposition monitor device and system for monitoring the deposition of ultra-thin films and nanomaterials and the analysis thereof is characterized by acoustic wave device embodiments that include differential delay line device designs, and which can optionally have integral reference devices fabricated on the same substrate as the sensing device, or on a separate device in thermal contact with the film monitoring/analysis device, in order to provide inherently temperature compensated measurements. These deposition monitor and analysis devices can include inherent temperature compensation, higher sensitivity to surface interactions than quartz crystal microbalance (QCM) devices, and the ability to operate at extreme temperatures.

Sub-ambient carbon dioxide adsorption properties of nitrogen doped graphene

Energy Technology Data Exchange (ETDEWEB)

Tamilarasan, P.; Ramaprabhu, Sundara, E-mail: ramp@iitm.ac.in [Alternative Energy and Nanotechnology Laboratory (AENL), Nano Functional Materials Technology Centre (NFMTC), Department of Physics, Indian Institute of Technology Madras, Chennai 600036 (India)

2015-04-14

Carbon dioxide adsorption on carbon surface can be enhanced by doping the surface with heterogeneous atoms, which can increase local surface affinity. This study presents the carbon dioxide adsorption properties of nitrogen doped graphene at low pressures (<100 kPa). Graphene was exposed to nitrogen plasma, which dopes nitrogen atoms into carbon hexagonal lattice, mainly in pyridinic and pyrrolic forms. It is found that nitrogen doping significantly improves the CO{sub 2} adsorption capacity at all temperatures, due to the enrichment of local Lewis basic sites. In general, isotherm and thermodynamic parameters suggest that doped nitrogen sites have nearly same adsorption energy of surface defects and residual functional groups. The isosteric heat of adsorption remains in physisorption range, which falls with surface coverage, suggesting the distribution of magnitude of adsorption energy. The absolute values of isosteric heat and entropy of adsorption are slightly increased upon nitrogen doping.

Surface water classification and monitoring using polarimetric synthetic aperture radar

Science.gov (United States)

Irwin, Katherine Elizabeth

Surface water classification using synthetic aperture radar (SAR) is an established practice for monitoring flood hazards due to the high temporal and spatial resolution it provides. Surface water change is a dynamic process that varies both spatially and temporally, and can occur on various scales resulting in significant impacts on affected areas. Small-scale flooding hazards, caused by beaver dam failure, is an example of surface water change, which can impact nearby infrastructure and ecosystems. Assessing these hazards is essential to transportation and infrastructure maintenance. With current satellite missions operating in multiple polarizations, spatio-temporal resolutions, and frequencies, a comprehensive comparison between SAR products for surface water monitoring is necessary. In this thesis, surface water extent models derived from high resolution single-polarization TerraSAR-X (TSX) data, medium resolution dual-polarization TSX data and low resolution quad-polarization RADARSAT-2 (RS-2) data are compared. There exists a compromise between acquiring SAR data with a high resolution or high information content. Multi-polarization data provides additional phase and intensity information, which makes it possible to better classify areas of flooded vegetation and wetlands. These locations are often where fluctuations in surface water occur and are essential for understanding dynamic underlying processes. However, often multi-polarized data is acquired at a low resolution, which cannot image these zones effectively. High spatial resolution, single-polarization TSX data provides the best model of open water. However, these single-polarization observations have limited information content and are affected by shadow and layover errors. This often hinders the classification of other land cover types. The dual-polarization TSX data allows for the classification of flooded vegetation, but classification is less accurate compared to the quad-polarization RS-2 data

Monitoring of tritium-contaminated surfaces, including skin

Energy Technology Data Exchange (ETDEWEB)

Surette, R A; Wood, M J

1994-05-01

We have examined various commercially available tritium surface contamination monitors along with different swipe media and techniques for direct and indirect (swipe) monitoring of contaminated surfaces, including skin. None of the methods or instruments evaluated were more sensitive than the swipe and liquid scintillation counting (LSC) method. Swipe measurements with open-window proportional counters were, in general, less than half as sensitive as LSC, but have the advantages of having the results available almost immediately, and no sample preparation is required. The Nuclear Measurement Corporation`s PC-55 is the most suitable instrument we tested for the analysis of routine swipe measurement. The PC-55 was about one third as sensitive as LSC when used with Ontario Hydro filter paper swipe media. Surface contamination measurement results can be obtained within minutes using the PC-55, compared to hours using LSC. The selection of swipe media for use with proportional counter-based instruments is critical. A medium that is electrically insulating can develop an electrostatic charge on its surface; this may alter the field gradient in the detector and may adversely influence the results. Although the PC-55 is sufficiently sensitive and very convenient, operational experience with the instrument is needed before recommending that it replace current LSC methods. The PC-55`s susceptibility to internal tritium contamination may limit its practical usefulness. Because of the complexity of using live animals to evaluate direct and indirect methods for assessing skin contamination, pig skin was investigated as a possible substitute. We concluded that, for the first few hours post-exposure, pig skin mimics the kinetics of animal skin that has contacted a tritium-contaminated surface. (author). 30 refs., 1 tab., 7 figs.

Decadal changes in summertime reactive oxidized nitrogen and surface ozone over the Southeast United States

Science.gov (United States)

Li, Jingyi; Mao, Jingqiu; Fiore, Arlene M.; Cohen, Ronald C.; Crounse, John D.; Teng, Alex P.; Wennberg, Paul O.; Lee, Ben H.; Lopez-Hilfiker, Felipe D.; Thornton, Joel A.; Peischl, Jeff; Pollack, Ilana B.; Ryerson, Thomas B.; Veres, Patrick; Roberts, James M.; Neuman, J. Andrew; Nowak, John B.; Wolfe, Glenn M.; Hanisco, Thomas F.; Fried, Alan; Singh, Hanwant B.; Dibb, Jack; Paulot, Fabien; Horowitz, Larry W.

2018-02-01

Widespread efforts to abate ozone (O3) smog have significantly reduced emissions of nitrogen oxides (NOx) over the past 2 decades in the Southeast US, a place heavily influenced by both anthropogenic and biogenic emissions. How reactive nitrogen speciation responds to the reduction in NOx emissions in this region remains to be elucidated. Here we exploit aircraft measurements from ICARTT (July-August 2004), SENEX (June-July 2013), and SEAC4RS (August-September 2013) and long-term ground measurement networks alongside a global chemistry-climate model to examine decadal changes in summertime reactive oxidized nitrogen (RON) and ozone over the Southeast US. We show that our model can reproduce the mean vertical profiles of major RON species and the total (NOy) in both 2004 and 2013. Among the major RON species, nitric acid (HNO3) is dominant (˜ 42-45 %), followed by NOx (31 %), total peroxy nitrates (ΣPNs; 14 %), and total alkyl nitrates (ΣANs; 9-12 %) on a regional scale. We find that most RON species, including NOx, ΣPNs, and HNO3, decline proportionally with decreasing NOx emissions in this region, leading to a similar decline in NOy. This linear response might be in part due to the nearly constant summertime supply of biogenic VOC emissions in this region. Our model captures the observed relative change in RON and surface ozone from 2004 to 2013. Model sensitivity tests indicate that further reductions of NOx emissions will lead to a continued decline in surface ozone and less frequent high-ozone events.

Radiological monitoring plan for the Oak Ridge Y-12 Plant: Surface Water

International Nuclear Information System (INIS)

1997-10-01

The Y-12 Plant conducts a surface water monitoring program in response to DOE Orders and state of Tennessee requirements under the National Pollutant Discharge Elimination System (NPDES). The anticipated codification of DOE Order 5400.5 for radiation protection of the public and the environment (10 CFR Part 834) will require an environmental radiation protection plan (ERPP). The NPDES permit issued by the state of Tennessee requires a radiological monitoring plan (RMP) for Y-12 Plant surface waters. In a May 4, 1995 memo, the state of Tennessee, Division of Water Pollution Control, stated their desired needs and goals regarding the content of RMPs, associated documentation, and data resulting from the RMPs required under the NPDES permitting system (L. Bunting, General Discussion, Radiological Monitoring Plans, Tennessee Division of Water Pollution Control, May 4,1995). Appendix A provides an overview of how the Y-12 Plant will begin to address these needs and goals. It provides a more complete, documented basis for the current Y-12 Plant surface water monitoring program and is intended to supplement documentation provided in the Annual Site Environmental Reports (ASERs), NPDES reports, Groundwater Quality Assessment Reports, and studies conducted under the Y-12 Plant Environmental Restoration (ER) Program. The purpose of this update to the Y-12 Plant RMP is to satisfy the requirements of the current NPDES permit, DOE Order 5400.5, and 10 CFR Part 834, as current proposed, by defining the radiological monitoring plan for surface water for the Y-12 Plant. This plan includes initial storm water monitoring and data analysis. Related activities such as sanitary sewer and sediment monitoring are also summarized. The plan discusses monitoring goals necessary to determine background concentrations of radionuclides, to quantify releases, determine trends, satisfy regulatory requirements, support consequence assessments, and meet requirements that releases be ''as low as

Structural characteristics of surface-functionalized nitrogen-doped diamond-like carbon films and effective adjustment to cell attachment

International Nuclear Information System (INIS)

Liu Ai-Ping; Liu Min; Yu Jian-Can; Qian Guo-Dong; Tang Wei-Hua

2015-01-01

Nitrogen-doped diamond-like carbon (DLC:N) films prepared by the filtered cathodic vacuum arc technology are functionalized with various chemical molecules including dopamine (DA), 3-Aminobenzeneboronic acid (APBA), and adenosine triphosphate (ATP), and the impacts of surface functionalities on the surface morphologies, compositions, microstructures, and cell compatibility of the DLC:N films are systematically investigated. We demonstrate that the surface groups of DLC:N have a significant effect on the surface and structural properties of the film. The activity of PC12 cells depends on the particular type of surface functional groups of DLC:N films regardless of surface roughness and wettability. Our research offers a novel way for designing functionalized carbon films as tailorable substrates for biosensors and biomedical engineering applications. (paper)

Comparative study of nitrogen fertilizer use efficiency of cotton grown under conventional and fertigation practices using 15N methodology

International Nuclear Information System (INIS)

Janat, M.; Somi, G.

2002-01-01

Nitrogen fertilization and irrigation methods are the key factors of yield increase. With proper management of these two factors a good production and protection of the environment could be attained at the same time. Field experiments were carried out at Hama (Tezeen's Agricultural Research Station) for four consecutive years 1995=1998. The objectives of this study were: Assessment of nitrogen fertilizer use efficiency (NFUE) under conventional and fertigation practices; Nitrogen requirements of cotton crop grown under fertigation practices: Comparative study of water use efficiency (WUE), and seed cotton yield of cotton crop grown under conventional and drip irrigation. Treatments consisted of five nitrogen rates for the fertigated cotton crop (0, 60, 120, 180 and 240 kg N ha -1 ). While of the surface irrigated cotton treatment only one recommended rate by MAAR was applied (180 kg N ha -1 ). Irrigation methods and N treatments were arranged in RBD. The soil water content and available soil nitrogen were monitored according to the standard procedures. The results revealed that fertigation of cotton under the given circumstances improved water use efficiency, nitrogen use efficiency, seed cotton yield, dry matter production, earliness and in some cases lint properties. Under fertigation practices 35-55% of the irrigation water was saved in comparison with surface irrigated cotton grown under the same condition. The seed cotton yield was increased by more than 50% relatively to the surface irrigated cotton. Furthermore, water use efficiency of the fertigated cotton was increased by almost 90 %. (author)

Luminescence properties of engineered nitrogen vacancy centers in a close surface proximity

Czech Academy of Sciences Publication Activity Database

Petráková, V.; Nesládek, M.; Taylor, Andrew; Fendrych, František; Cígler, Petr; Ledvina, Miroslav; Vacík, Jiří; Štursa, Jan; Kučka, Jan

2011-01-01

Roč. 208, č. 9 (2011), s. 2051-2056 ISSN 1862-6300 R&D Projects : GA AV ČR KAN200100801; GA AV ČR KAN301370701; GA AV ČR(CZ) KAN400480701; GA MŠk(CZ) LD11076 EU Projects : European Commission(XE) 245122 - DINAMO Grant - others:GA MŠk(CZ) LD11078; European RD projects (XE) 238201-MATCON Institutional research plan: CEZ:AV0Z40550506; CEZ:AV0Z10100520; CEZ:AV0Z10480505 Keywords : diamond * luminescence properties * nitrogen-vacancy * surface proximity Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.463, year: 2011

Transient atomic behavior and surface kinetics of GaN

International Nuclear Information System (INIS)

Moseley, Michael; Billingsley, Daniel; Henderson, Walter; Trybus, Elaissa; Doolittle, W. Alan

2009-01-01

An in-depth model for the transient behavior of metal atoms adsorbed on the surface of GaN is developed. This model is developed by qualitatively analyzing transient reflection high energy electron diffraction (RHEED) signals, which were recorded for a variety of growth conditions of GaN grown by molecular-beam epitaxy (MBE) using metal-modulated epitaxy (MME). Details such as the initial desorption of a nitrogen adlayer and the formation of the Ga monolayer, bilayer, and droplets are monitored using RHEED and related to Ga flux and shutter cycles. The suggested model increases the understanding of the surface kinetics of GaN, provides an indirect method of monitoring the kinetic evolution of these surfaces, and introduces a novel method of in situ growth rate determination.

Transient atomic behavior and surface kinetics of GaN

Science.gov (United States)

Moseley, Michael; Billingsley, Daniel; Henderson, Walter; Trybus, Elaissa; Doolittle, W. Alan

2009-07-01

An in-depth model for the transient behavior of metal atoms adsorbed on the surface of GaN is developed. This model is developed by qualitatively analyzing transient reflection high energy electron diffraction (RHEED) signals, which were recorded for a variety of growth conditions of GaN grown by molecular-beam epitaxy (MBE) using metal-modulated epitaxy (MME). Details such as the initial desorption of a nitrogen adlayer and the formation of the Ga monolayer, bilayer, and droplets are monitored using RHEED and related to Ga flux and shutter cycles. The suggested model increases the understanding of the surface kinetics of GaN, provides an indirect method of monitoring the kinetic evolution of these surfaces, and introduces a novel method of in situ growth rate determination.

Heavily nitrogen doped, graphene supercapacitor from silk cocoon

International Nuclear Information System (INIS)

Sahu, Vikrant; Grover, Sonia; Tulachan, Brindan; Sharma, Meenakshi; Srivastava, Gaurav; Roy, Manas; Saxena, Manav; Sethy, Niroj; Bhargava, Kalpana; Philip, Deepu; Kim, Hansung; Singh, Gurmeet; Singh, Sushil Kumar; Das, Mainak; Sharma, Raj Kishore

2015-01-01

Doping of graphene with nitrogen is of much interest, since it improves the overall conductivity and supercapacitive properties. Besides conductivity, nitrogen doping also enhances the pseudo-capacitance due to fast and reversible surface redox processes. In this work, we have developed a cheap and easy process for synthesizing heavily nitrogen doped graphene (15% nitrogen) from non-mulberry silk cocoon membrane (Tassar, Antheraea mylitta) by pyrolyzing the cocoon at 400 °C in argon atmosphere. Further we have investigated the performance of this heavily ‘nitrogen doped graphene’ (NDG) in a supercapacitor device. Our results suggest that NDG obtained from cocoon has improved supercapacitor performance. The improved performance is due to the high electronegativity of nitrogen that forms dipoles on the graphene surface. These dipoles consequently enhance the tendency of graphene to attract charged species to its surface. This is a green and clean synthesis approach for developing electronic materials for energy applications

Results from the Big Spring basin water quality monitoring and demonstration projects, Iowa, USA

Science.gov (United States)

Rowden, R.D.; Liu, H.; Libra, R.D.

2001-01-01

Agricultural practices, hydrology, and water quality of the 267-km2 Big Spring groundwater drainage basin in Clayton County, Iowa, have been monitored since 1981. Land use is agricultural; nitrate-nitrogen (-N) and herbicides are the resulting contaminants in groundwater and surface water. Ordovician Galena Group carbonate rocks comprise the main aquifer in the basin. Recharge to this karstic aquifer is by infiltration, augmented by sinkhole-captured runoff. Groundwater is discharged at Big Spring, where quantity and quality of the discharge are monitored. Monitoring has shown a threefold increase in groundwater nitrate-N concentrations from the 1960s to the early 1980s. The nitrate-N discharged from the basin typically is equivalent to over one-third of the nitrogen fertilizer applied, with larger losses during wetter years. Atrazine is present in groundwater all year; however, contaminant concentrations in the groundwater respond directly to recharge events, and unique chemical signatures of infiltration versus runoff recharge are detectable in the discharge from Big Spring. Education and demonstration efforts have reduced nitrogen fertilizer application rates by one-third since 1981. Relating declines in nitrate and pesticide concentrations to inputs of nitrogen fertilizer and pesticides at Big Spring is problematic. Annual recharge has varied five-fold during monitoring, overshadowing any water-quality improvements resulting from incrementally decreased inputs. ?? Springer-Verlag 2001.

Modeling and Simulated Annealing Optimization of Surface Roughness in CO2 Laser Nitrogen Cutting of Stainless Steel

OpenAIRE

M. Madić; M. Radovanović; B. Nedić

2013-01-01

This paper presents a systematic methodology for empirical modeling and optimization of surface roughness in nitrogen, CO2 laser cutting of stainless steel . The surface roughness prediction model was developed in terms of laser power , cutting speed , assist gas pressure and focus position by using The artificial neural network ( ANN ) . To cover a wider range of laser cutting parameters and obtain an experimental database for the ANN model development, Taguchi 's L27 orthogonal array was im...

Surface reconstruction and deformation monitoring of stratospheric airship based on laser scanning technology

Science.gov (United States)

Guo, Kai; Xie, Yongjie; Ye, Hu; Zhang, Song; Li, Yunfei

2018-04-01

Due to the uncertainty of stratospheric airship's shape and the security problem caused by the uncertainty, surface reconstruction and surface deformation monitoring of airship was conducted based on laser scanning technology and a √3-subdivision scheme based on Shepard interpolation was developed. Then, comparison was conducted between our subdivision scheme and the original √3-subdivision scheme. The result shows our subdivision scheme could reduce the shrinkage of surface and the number of narrow triangles. In addition, our subdivision scheme could keep the sharp features. So, surface reconstruction and surface deformation monitoring of airship could be conducted precisely by our subdivision scheme.

Solar-wind interactions with the Moon: nature and composition of nitrogen compounds

International Nuclear Information System (INIS)

Mukherjee, N.R.

1981-01-01

The lunar atmosphere and magnetic field are very tenuous. The solar wind, therefore, interacts directly with the lunar surface material and the dominant nature of interaction is essentially complete absorption of solar-wind particles by the surface material resulting in no upstream bowshock, but a cavity downstream. The solar-wind nitrogen ion species induce and undergo a complex set of reactions with the elements of lunar material and the solar-wind-derived trapped elements. The nitrogen concentration indigeneous to the lunar surface material is practically nil. Therefore any nitrogen and nitrogen compounds found in the lunar surface material are due to the solar-wind implantation of nitrogen ions. The flux of the solar-wind nitrogen ion species is about 6 X 10 3 cm -2 s -1 . Since there is no evidence for accumulation of nitrogen species in the lunar surface material, the outflux of nitrogen species from the lunar material to the atmosphere is the same as the solar-wind nitrogen ion flux. The species of the outflux are primarily NO and NH 3 , and their respective concentrations in the near surface lunar atmosphere are found to be 327 and 295 cm -3 . (Auth.)

X-ray photoelectron spectroscopic depth profilometry of nitrogen implanted in materials for modification of their surface properties

International Nuclear Information System (INIS)

Sarkissian, A.H.; Paynter, R.; Stansfield, B.L.

1996-01-01

The modification of the surface properties of materials has a wide range of industrial applications. For example, the authors change the electrical characteristics of semiconductors, improve surface hardness, decrease friction, increase resistance to corrosion, improve adhesion, etc. Nitriding is one of the most common processes used in industry for surface treatment. Nitrogen ion implantation is one technique often used to achieve this goal. Ion implantation offers the power to control the deposition profile, and can be achieved by either conventional ion beam implantation or plasma assisted ion implantation. They have used the technique of plasma assisted ion implantation to implant nitrogen in several materials, including titanium, silicon and stainless steel. The plasma source is a surface ECR source developed at INRS-Energie et Materiaux. The depth profile of the implanted ions has been measured by X-ray photoelectron spectroscopy. They have also conducted simulations using the TRIM-95 code to predict the depth profile of the implanted ions. Comparisons of the measured results with those from simulations are used to deduce information regarding the plasma composition and the collisional effects in the plasma. A fast responding, current and voltage measuring circuit with fiber optic links is being developed, which allows more accurate quantitative measurements. Further experiments to study the characteristics of the plasma, and their effects on the characteristics of the implanted surfaces are in progress, and the results are presented at this meeting

Sensors and OBIA synergy for operational monitoring of surface water

Science.gov (United States)

Masson, Eric; Thenard, Lucas

2010-05-01

This contribution will focus on combining Object Based Image Analysis (i.e. OBIA with e-Cognition 8) and recent sensors (i.e. Spot 5 XS, Pan and ALOS Prism, Avnir2, Palsar) to address the technical feasibility for an operational monitoring of surface water. Three cases of river meandering (India), flood mapping (Nepal) and dam's seasonal water level monitoring (Morocco) using recent sensors will present various application of surface water monitoring. The operational aspect will be demonstrated either by sensor properties (i.e. spatial resolution and bandwidth), data acquisition properties (i.e. multi sensor, return period and near real-time acquisition) but also with OBIA algorithms (i.e. fusion of multi sensors / multi resolution data and batch processes). In the first case of river meandering (India) we will address multi sensor and multi date satellite acquisition to monitor the river bed mobility within a floodplain using an ALOS dataset. It will demonstrate the possibility of an operational monitoring system that helps the geomorphologist in the analysis of fluvial dynamic and sediment budget for high energy rivers. In the second case of flood mapping (Nepal) we will address near real time Palsar data acquisition at high spatial resolution to monitor and to map a flood extension. This ALOS sensor takes benefit both from SAR and L band properties (i.e. atmospheric transparency, day/night acquisition, low sensibility to surface wind). It's a real achievement compared to optical imagery or even other high resolution SAR properties (i.e. acquisition swath, bandwidth and data price). These advantages meet the operational needs set by crisis management of hydrological disasters but also for the implementation of flood risk management plans. The last case of dam surface water monitoring (Morocco) will address an important issue of water resource management in countries affected by water scarcity. In such countries water users have to cope with over exploitation

Second IRMF comparison of surface contamination monitor calibrations 2001-2002

CERN Document Server

Scott, C J

2002-01-01

The Ionising Radiations Metrology Forum (IRMF) organised a second comparison of surface contamination monitor calibrations in which twenty establishments in the UK participated. The exercise involved the circulation of three surface contamination monitors for calibration using large area reference sources available in the participants' laboratories. The instruments used were a Mini Instruments EP15, a Berthold LB122 and an Electra ratemeter with DP6AD probe. The instrument responses were calculated by the individual participants and submitted to the for analysis along with details of the reference sources used. Details of the estimated uncertainties were also reported. The results are compared and demonstrate generally satisfactory agreement between the participating establishments.

Nitrogen fate model for gas-phase ammonia-enhanced in situ bioventing

International Nuclear Information System (INIS)

Marshall, T.R.

1995-01-01

Subsurface bioremediation of contaminants is sometimes limited by the availability of nitrogen. Introduction of gaseous ammonia to the subsurface is a feasible and economical approach to enhance biodegradation in some environments. A gaseous nutrient source may be a practical option for sites where surface application of liquid nutrients is not possible, such as sites with shallow groundwater or sites with surface operations. A conceptual nitrogen fate model was developed to provide remediation scientists and engineers with some practical guidelines in the use of ammonia-enhanced bioventing. Ammonia supplied to the subsurface dissolves readily in soil moisture and sorbs strongly to soil particles. The ammonium ion is the preferred nutrient form of many microorganisms. Some of the ammonia will be converted to nitrate by ammonia-oxidizing organisms. Field monitoring data from an operating ammonia-enhanced bioventing remediation site for diesel fuel contamination are presented. Conservative additions of ammonia promoted appreciable increases in evolved carbon dioxide and rate of oxygen utilization. An overabundance of added ammonia promoted formation of methane from likely anaerobic hydrocarbon degradation in the presence of nitrate as the electron acceptor

Decadal changes in summertime reactive oxidized nitrogen and surface ozone over the Southeast United States

Directory of Open Access Journals (Sweden)

J. Li

2018-02-01

Full Text Available Widespread efforts to abate ozone (O3 smog have significantly reduced emissions of nitrogen oxides (NOx over the past 2 decades in the Southeast US, a place heavily influenced by both anthropogenic and biogenic emissions. How reactive nitrogen speciation responds to the reduction in NOx emissions in this region remains to be elucidated. Here we exploit aircraft measurements from ICARTT (July–August 2004, SENEX (June–July 2013, and SEAC4RS (August–September 2013 and long-term ground measurement networks alongside a global chemistry–climate model to examine decadal changes in summertime reactive oxidized nitrogen (RON and ozone over the Southeast US. We show that our model can reproduce the mean vertical profiles of major RON species and the total (NOy in both 2004 and 2013. Among the major RON species, nitric acid (HNO3 is dominant (∼ 42–45 %, followed by NOx (31 %, total peroxy nitrates (ΣPNs; 14 %, and total alkyl nitrates (ΣANs; 9–12 % on a regional scale. We find that most RON species, including NOx, ΣPNs, and HNO3, decline proportionally with decreasing NOx emissions in this region, leading to a similar decline in NOy. This linear response might be in part due to the nearly constant summertime supply of biogenic VOC emissions in this region. Our model captures the observed relative change in RON and surface ozone from 2004 to 2013. Model sensitivity tests indicate that further reductions of NOx emissions will lead to a continued decline in surface ozone and less frequent high-ozone events.

Inhibition of methane oxidation in slurry surface crust by inorganic nitrogen

DEFF Research Database (Denmark)

Duan, Yun-Feng; Elsgaard, Lars; Petersen, Søren O

2013-01-01

Livestock slurry is an important source of methane (CH4). Depending on dry matter content, a floating crust may form where methane-oxidizing bacteria (MOB) and CH4 oxidation activity have been found, suggesting that surface crusts may reduce CH4 emissions from slurry. However, it is not known how...... MOB in this environment interact with inorganic nitrogen (N). We studied inhibitory effects of ammonium (NH4+), nitrate (NO3–) and nitrite (NO2–) on potential CH4 oxidation in a cattle slurry surface crust. Methane oxidation was assayed at salt concentrations up to 500 mM at 100 and 10,000 ppmv...... headspace CH4. First-order rate constants were used to evaluate the strength of inhibition. Nitrite was the most potent inhibitor, reducing methanotrophic activity by up to 70% at only 1 mM NO2–. MOB were least sensitive to NO3–, tolerating up to 30 mM NO3– at 100 ppmv CH4 and 50 mM NO3– at 10,000 ppmv CH4...

Tritium contaminated surface monitoring with a solid - state device

International Nuclear Information System (INIS)

Culcer, Mihai; Iliescu, Mariana; Curuia, Marian; Enache, Adrian; Stefanescu, Ioan; Ducu, Catalin; Malinovschi, Viorel

2004-01-01

The low energy of betas makes tritium difficult to detect. However, there are several methods used in tritium detection, such as liquid scintillation and ionization chambers. Tritium on or near a surface can be also detected using proportional counters and, recently, solid state devices. The paper presents our results in the design and achievement of a surface tritium monitor using a PIN photodiode as a solid state charged particle detector to count betas emitted from the surface. That method allows continuous, real-time and non-destructively measuring of tritium. (authors)

Design and Season Influence Nitrogen Dynamics in Two Surface Flow Constructed Wetlands Treating Nursery Irrigation Runoff

Directory of Open Access Journals (Sweden)

Sarah A. White

2017-12-01

Full Text Available Constructed wetlands (CWs are used to remediate runoff from a variety of agricultural, industrial, and urban sources. CW remediation performance is often evaluated at the laboratory scale over durations less than one year. The purpose of this study was to characterize the effect of CW design (cell depth and residence time on nitrogen (N speciation and fate across season and years in two free water surface wetlands receiving runoff from irrigated plant production areas at an ornamental plant nursery. Water quality (mg·L−1 of nitrate, nitrite, and ammonium, dissolved oxygen and oxidation reduction potential was monitored at five sites within each of two CWs each month over four years. Nitrate-N was the dominant form of ionic N present in both CWs. Within CW1, a deep cell to shallow cell design, nitrate comprised 86% of ionic N in effluent. Within CW2, designed with three sequential deep cells, nitrate comprised only 66% of total N and ammonium comprised 27% of total N in CW2 effluent. Differences in ionic N removal efficacies and shifts in N speciation in CW1 and CW2 were controlled by constructed wetland design (depth and hydraulic retention time, the concentration of nutrients entering the CW, and plant species richness.

Acoustic emission-based in-process monitoring of surface generation in robot-assisted polishing

DEFF Research Database (Denmark)

Pilny, Lukas; Bissacco, Giuliano; De Chiffre, Leonardo

2016-01-01

The applicability of acoustic emission (AE) measurements for in-process monitoring of surface generation in the robot-assisted polishing (RAP) was investigated. Surface roughness measurements require interruption of the process, proper surface cleaning and measurements that sometimes necessitate...... automatic detection of optimal process endpoint allow intelligent process control, creating fundamental elements in development of robust fully automated RAP process for its widespread industrial application....... removal of the part from the machine tool. In this study, stabilisation of surface roughness during polishing rotational symmetric surfaces by the RAP process was monitored by AE measurements. An AE sensor was placed on a polishing arm in direct contact with a bonded abrasive polishing tool...

INCREASE OF ADHESION OF PAINT-AND-LACQUER MATERIALS TO WOOD THROUGH THE MODIFICATION OF ITS SURFACE BY BORON-NITROGEN COMPOUNDS

Directory of Open Access Journals (Sweden)

Koteneva Irina Vasil'evna

2012-10-01

Full Text Available The authors demonstrate that the efficiency of protection of wooden structures, covered with paints and lacquer materials, from the influence of the environment, depends on the adhesion size. It is common knowledge that improvement of adhesion of capillary-porous materials to the wood, and, hence, the increase of the service life of the sheeting requires the reduction in the dimensions of the wood surface, as the reduction of diameters of capillaries leads to the growth of forces of capillary condensation and to the increase in the depth of penetration of paints into the material. Adhesion of a water-soluble acrylic paint and organic-soluble enamels to the surface of the wood modified by boron-nitrogen compounds and to unmodified wood is the subject of the research. It is identified that the increase in the adhesive durability of paint and varnish coverings if glued to the surface of the wood modified by boron-nitrogen compounds, is driven by the growth of the polarity of a substrate and the reduction of dimensions of the wood surface.

Deposition and surface characterization of nanoparticles of zinc oxide using dense plasma focus device in nitrogen atmosphere

International Nuclear Information System (INIS)

Malhotra, Yashi; Srivastava, M P; Roy, Savita

2010-01-01

Nanoparticles of zinc oxide from zinc oxide pellets in the nitrogen plasma atmosphere are deposited on n and p type silicon substrates using Dense Plasma Focus device. The hot and dense nitrogen plasma formed during the focus phase ionizes the ZnO pellet, which then move upward in a fountain like shape and gets deposited on substrates which are placed above the top of the anode. Structural and surface properties of the deposited ZnO are investigated using X-ray diffraction and Atomic force microscope (AFM). X-ray spectra shows the diffraction plane (002) of ZnO nanoparticles deposited on Si with few shots in nitrogen atmosphere. AFM investigations revealed that there are nanoparticles of size between 15-80 nm on n-Si and p-Si substrates. The deposition on n-type Si is better than the p-type Si can be seen from AFM images, this may be due to different orientation of silicon.

High-Resolution Electron Energy Loss Studies of Oxygen, Hydrogen, Nitrogen, Nitric Oxide, and Nitrous Oxide Adsorption on Germanium Surfaces.

Science.gov (United States)

Entringer, Anthony G.

The first high resolution electron energy loss spectroscopy (HREELS) studies of the oxidation and nitridation of germanium surfaces are reported. Both single crystal Ge(111) and disordered surfaces were studied. Surfaces were exposed to H, O_2, NO, N _2O, and N, after cleaning in ultra-high vacuum. The Ge surfaces were found to be non-reactive to molecular hydrogen (H_2) at room temperature. Exposure to atomic hydrogen (H) resulted hydrogen adsorption as demonstrated by the presence of Ge-H vibrational modes. The HREEL spectrum of the native oxide of Ge characteristic of nu -GeO_2 was obtained by heating the oxide to 200^circC. Three peaks were observed at 33, 62, and 106 meV for molecular oxygen (O_2) adsorbed on clean Ge(111) at room temperature. These peaks are indicative of dissociative bonding and a dominant Ge-O-Ge bridge structure. Subsequent hydrogen exposure resulted in a shift of the Ge-H stretch from its isolated value of 247 meV to 267 meV, indicative of a dominant +3 oxidation state. A high density of dangling bonds and defects and deeper oxygen penetration at the amorphous Ge surface result in a dilute bridge structure with a predominant +1 oxidation state for similar exposures. Molecules of N_2O decompose at the surfaces to desorbed N_2 molecules and chemisorbed oxygen atoms. In contrast, both oxygen and nitrogen are detected at the surfaces following exposure to NO molecules. Both NO and N_2O appear to dissociate and bond at the top surface layer. Molecular nitrogen (N_2) does not react with the Ge surfaces, however, a precursor Ge nitride is observed at room temperature following exposure to nitrogen atoms and ions. Removal of oxygen by heating of the NO-exposed surface to 550^circC enabled the identification of the Ge-N vibrational modes. These modes show a structure similar to that of germanium nitride. This spectrum is also identical to that of the N-exposed surface heated to 550^circC. Surface phonon modes of the narrow-gap semiconducting

A multimodal optical and electrochemical device for monitoring surface reactions: redox active surfaces in porous silicon Rugate filters.

Science.gov (United States)

Ciampi, Simone; Guan, Bin; Darwish, Nadim A; Zhu, Ying; Reece, Peter J; Gooding, J Justin

2012-12-21

Herein, mesoporous silicon (PSi) is configured as a single sensing device that has dual readouts; as a photonic crystal sensor in a Rugate filter configuration, and as a high surface area porous electrode. The as-prepared PSi is chemically modified to provide it with stability in aqueous media and to allow for the subsequent coupling of chemical species, such as via Cu(I)-catalyzed cycloaddition reactions between 1-alkynes and azides ("click" reactions). The utility of the bimodal capabilities of the PSi sensor for monitoring surface coupling procedures is demonstrated by the covalent coupling of a ferrocene derivative, as well as by demonstrating ligand-exchange reactions (LER) at the PSi surface. Both types of reactions were monitored through optical reflectivity measurements, as well as electrochemically via the oxidation/reduction of the surface tethered redox species.

Simulation of ammoniacal nitrogen effluent using feedforward ...

African Journals Online (AJOL)

Ammoniacal nitrogen in domestic wastewater treatment plants has recently been added as the monitoring parameter by the Department of Environment, Malaysia. It is necessary to obtain a suitable model for the simulation of ammonical nitrogen in the effluent stream of sewage treatment plant in order to meet the new ...

Impact of Surface Functionalization on the Quantum Coherence of Nitrogen-Vacancy Centers in Nanodiamonds.

Science.gov (United States)

Ryan, Robert G; Stacey, Alastair; O'Donnell, Kane M; Ohshima, Takeshi; Johnson, Brett C; Hollenberg, Lloyd C L; Mulvaney, Paul; Simpson, David A

2018-04-18

Nanoscale quantum probes such as the nitrogen-vacancy (NV) center in diamonds have demonstrated remarkable sensing capabilities over the past decade as control over fabrication and manipulation of these systems has evolved. The biocompatibility and rich surface chemistry of diamonds has added to the utility of these probes but, as the size of these nanoscale systems is reduced, the surface chemistry of diamond begins to impact the quantum properties of the NV center. In this work, we systematically study the effect of the diamond surface chemistry on the quantum coherence of the NV center in nanodiamonds (NDs) 50 nm in size. Our results show that a borane-reduced diamond surface can on average double the spin relaxation time of individual NV centers in nanodiamonds when compared to thermally oxidized surfaces. Using a combination of infrared and X-ray absorption spectroscopy techniques, we correlate the changes in quantum relaxation rates with the conversion of sp 2 carbon to C-O and C-H bonds on the diamond surface. These findings implicate double-bonded carbon species as a dominant source of spin noise for near surface NV centers. The link between the surface chemistry and quantum coherence indicates that through tailored engineering of the surface, the quantum properties and magnetic sensitivity of these nanoscale systems may approach that observed in bulk diamond.

Trends in nitrogen concentrations and load in 48 minor streams draining intensively farmed Danish catchments, 1990-2014. How can the observed trend be explained?

Science.gov (United States)

Windolf, Jørgen; Børgesen, Christen; Blicher-Mathiesen, Gitte; Kronvang, Brian; Larsen, Søren E.; Tornbjerg, Henrik

2016-04-01

The total land-based nitrogen load to Danish coastal waters has decreased by 50% since 1990 through a reduction of the outlet of nitrogen from sewage point sources and diffuse sources. On a national scale nitrogen load from diffuse sources, has been reduced by 43% , mainly due to limitation of the amount of N input to different crops, rules for timing and application of manure, mandatory demands for catch crops and restoration of wetlands. The latter increasing the nitrogen retention capacity in surface waters. However, on a local scale huge variations exist in the reduction of the diffuse nitrogen load. Since 1990, an important part of the Danish national monitoring program on the aquatic environment (NOVANA) has been directed at quantifying the nitrogen concentrations and load in 48 minor streams draining small intensively farmed catchments. The 48 catchments have a mean size of 18 km2, farmed area constitutes more than 60% of the catchment area and the catchments have no significant outlets of sewage to the streams. The statistical trend results (based on a seasonal Mann-Kendall) from these 48 streams show a 9-65% reduction in the diffuse nitrogen load (mean: 48%). The large differences in trends in the diffuse N load are related to differences in catchment-specific variables such as nitrogen surpluses, nitrogen leaching from the root zone, hydrogeology and nitrogen retention in ground and surface waters.

Estimating space-time mean concentrations of nutrients in surface waters of variable depth

NARCIS (Netherlands)

Knotters, M.; Brus, D.J.

2010-01-01

A monitoring scheme has been designed to test whether the space-time mean concentration total Nitrogen (N-total) in the surface water in the Northern Frisian Woodlands (NFW, The Netherlands) complies with standards of the European Water Framework directive. Since in statistical testing for

Investigations of Nitrogen Oxide Plasmas: Fundamental Chemistry and Surface Reactivity and Monitoring Student Perceptions in a General Chemistry Recitation

Science.gov (United States)

Blechle, Joshua M.

2016-01-01

Part I of this dissertation focuses on investigations of nitrogen oxide plasma systems. With increasing concerns over the environmental presence of NxOy species, there is growing interest in utilizing plasma-assisted conversion techniques. Advances, however, have been limited because of the lack of knowledge regarding the fundamental chemistry of…

The nitrogen cycle: Atmosphere interactions

Science.gov (United States)

Levine, J. S.

1984-01-01

Atmospheric interactions involving the nitrogen species are varied and complex. These interactions include photochemical reactions, initiated by the absorption of solar photons and chemical kinetic reactions, which involve both homogeneous (gas-to-gas reactions) and heterogeneous (gas-to-particle) reactions. Another important atmospheric interaction is the production of nitrogen oxides by atmospheric lightning. The nitrogen cycle strongly couples the biosphere and atmosphere. Many nitrogen species are produced by biogenic processes. Once in the atmosphere nitrogen oxides are photochemically and chemically transformed to nitrates, which are returned to the biosphere via precipitation, dry deposition and aerosols to close the biosphere-atmosphere nitrogen cycle. The sources, sinks and photochemistry/chemistry of the nitrogen species; atmospheric nitrogen species; souces and sinks of nitrous oxide; sources; sinks and photochemistry/chemistry of ammonia; seasonal variation of the vertical distribution of ammonia in the troposphere; surface and atmospheric sources of the nitrogen species, and seasonal variation of ground level ammonia are summarized.

Surface Acoustic Wave (SAW Resonators for Monitoring Conditioning Film Formation

Directory of Open Access Journals (Sweden)

Siegfried Hohmann

2015-05-01

Full Text Available We propose surface acoustic wave (SAW resonators as a complementary tool for conditioning film monitoring. Conditioning films are formed by adsorption of inorganic and organic substances on a substrate the moment this substrate comes into contact with a liquid phase. In the case of implant insertion, for instance, initial protein adsorption is required to start wound healing, but it will also trigger immune reactions leading to inflammatory responses. The control of the initial protein adsorption would allow to promote the healing process and to suppress adverse immune reactions. Methods to investigate these adsorption processes are available, but it remains difficult to translate measurement results into actual protein binding events. Biosensor transducers allow user-friendly investigation of protein adsorption on different surfaces. The combination of several transduction principles leads to complementary results, allowing a more comprehensive characterization of the adsorbing layer. We introduce SAW resonators as a novel complementary tool for time-resolved conditioning film monitoring. SAW resonators were coated with polymers. The adsorption of the plasma proteins human serum albumin (HSA and fibrinogen onto the polymer-coated surfaces were monitored. Frequency results were compared with quartz crystal microbalance (QCM sensor measurements, which confirmed the suitability of the SAW resonators for this application.

A nitrogen index to track changes in butterfly species assemblages under nitrogen deposition

NARCIS (Netherlands)

Wallis de Vries, Michiel; Swaay, van Chris A.M.

2017-01-01

The impacts of nitrogen deposition (N) on animal communities are still poorly understood in comparison to plant communities. Long-term monitoring of community changes may contribute to this understanding, complementing experimental studies on underlying mechanisms. Butterflies are particularly

Does high reactive nitrogen input from the atmosphere decrease the carbon sink strength of a peatland?

Science.gov (United States)

Brümmer, Christian; Zöll, Undine; Hurkuck, Miriam; Schrader, Frederik; Kutsch, Werner

2017-04-01

Mid-latitude peatlands are often exposed to high atmospheric nitrogen deposition when located in close vicinity to agricultural land. As the impacts of altered deposition rates on nitrogen-limited ecosystems are poorly understood, we investigated the surface-atmosphere exchange of several nitrogen and carbon compounds using multiple high-resolution measurement techniques and modeling. Our study site was a protected semi-natural bog ecosystem. Local wind regime and land use in the adjacent area clearly regulated whether total reactive nitrogen (ΣNr) concentrations were ammonia (NH3) or NOx-dominated. Eddy-covariance measurements of NH3 and ΣNr revealed concentration, temperature and surface wetness-dependent deposition rates. Intermittent periods of NH3 and ΣNr emission likely attributed to surface water re-emission and soil efflux, respectively, were found, thereby indicating nitrogen oversaturation in this originally N-limited ecosystem. Annual dry plus wet deposition resulted in 20 to 25 kg N ha-1 depending on method and model used, which translated into a four- to fivefold exceedance of the ecosystem-specific critical load. As the bog site had likely been exposed to the observed atmospheric nitrogen burden over several decades, a shift in grass species' composition towards a higher number of nitrophilous plants was already visible. Three years of CO2 eddy flux measurements showed that the site was a small net sink in the range of 33 to 268 g CO2 m-2 yr-1. Methane emissions of 32 g CO2-eq were found to partly offset the sequestered carbon through CO2. Our study indicates that the sink strength of the peatland has likely been decreased through elevated N deposition over the past decades. It also demonstrates the applicability of novel micrometeorological measurement techniques in biogeochemical sciences and stresses the importance of monitoring long-term changes in vulnerable ecosystems under anthropogenic pressure and climate change.

Frequency Selective Surface for Structural Health Monitoring

Science.gov (United States)

Norlyana Azemi, Saidatul; Mustaffa, Farzana Hazira Wan; Faizal Jamlos, Mohd; Abdullah Al-Hadi, Azremi; Soh, Ping Jack

2018-03-01

Structural health monitoring (SHM) technologies have attained attention to monitor civil structures. SHM sensor systems have been used in various civil structures such as bridges, buildings, tunnels and so on. However the previous sensor for SHM is wired and encounter with problem to cover large areas. Therefore, wireless sensor was introduced for SHM to reduce network connecting problem. Wireless sensors for Structural Health monitoring are new technology and have many advantages to overcome the drawback of conventional and wired sensor. This project proposed passive wireless SHM sensor using frequency selective surface (FSS) as an alternative to conventional sensors. The electromagnetic wave characteristic of FSS will change by geometrical changes of FSS due to mechanical strain or structural failure. The changes feature is used as a sensing function without any connecting wires. Two type of design which are circular ring and square loop along with the transmission and reflection characteristics of SHM using FSS were discussed in this project. A simulation process has shown that incident angle characteristics can be use as a data for SHM application.

Runoff load estimation of particulate and dissolved nitrogen in Lake Inba watershed using continuous monitoring data on turbidity and electric conductivity.

Science.gov (United States)

Kim, J; Nagano, Y; Furumai, H

2012-01-01

Easy-to-measure surrogate parameters for water quality indicators are needed for real time monitoring as well as for generating data for model calibration and validation. In this study, a novel linear regression model for estimating total nitrogen (TN) based on two surrogate parameters is proposed based on evaluation of pollutant loads flowing into a eutrophic lake. Based on their runoff characteristics during wet weather, electric conductivity (EC) and turbidity were selected as surrogates for particulate nitrogen (PN) and dissolved nitrogen (DN), respectively. Strong linear relationships were established between PN and turbidity and DN and EC, and both models subsequently combined for estimation of TN. This model was evaluated by comparison of estimated and observed TN runoff loads during rainfall events. This analysis showed that turbidity and EC are viable surrogates for PN and DN, respectively, and that the linear regression model for TN concentration was successful in estimating TN runoff loads during rainfall events and also under dry weather conditions.

Development of a calibration system for surface contamination monitors

International Nuclear Information System (INIS)

Marechal, M.H.H.; Barbosa, M.P.

1992-01-01

A calibration system for surface contamination monitors is developed, aiming supply the existence demand of these instruments. A experimental arrangement and a methodology are described. The advantages of use this system for calibration routine optimization are also discussed. (C.G.C.)

Evaluation of broadband surface solar irradiance derived from the Ozone Monitoring Instrument

NARCIS (Netherlands)

Wang, P.; Sneep, M.; Veefkind, J.P.; Stammes, P.; Levelt, P.F.

2014-01-01

Surface solar irradiance (SSI) data are important for planning and estimating the production of solar power plants. Long-term high quality surface solar radiation data are needed for monitoring climate change. This paper presents a new surface solar irradiance dataset, the broadband (0.2–4 ?m)

Nitrogen biogeochemistry in the Adirondack Mountains of New York: hardwood ecosystems and associated surface waters

International Nuclear Information System (INIS)

Mitchell, Myron J.; Driscoll, Charles T.; Inamdar, Shreeram; McGee, Greg G.; Mbila, Monday O.; Raynal, Dudley J.

2003-01-01

Factors that regulate the fate of atmospherically deposited nitrogen to hardwood forests and subsequent transport to surface waters in the Adirondack region of New York are described. - Studies on the nitrogen (N) biogeochemistry in Adirondack northern hardwood ecosystems were summarized. Specific focus was placed on results at the Huntington Forest (HFS), Pancake-Hall Creek (PHC), Woods Lake (WL), Ampersand (AMO), Catlin Lake (CLO) and Hennessy Mountain (HM). Nitrogen deposition generally decreased from west to east in the Adirondacks, and there have been no marked temporal changes in N deposition from 1978 through 1998. Second-growth western sites (WL, PHC) had higher soil solution NO 3 - concentrations and fluxes than the HFS site in the central Adirondacks. Of the two old-growth sites (AMO and CLO), AMO had substantially higher NO 3 - concentrations due to the relative dominance of sugar maple that produced litter with high N mineralization and nitrification rates. The importance of vegetation in affecting N losses was also shown for N-fixing alders in wetlands. The Adirondack Manipulation and Modeling Project (AMMP) included separate experimental N additions of (NH 4 ) 2 SO 4 at WL, PHC and HFS and HNO 3 at WL and HFS. Patterns of N loss varied with site and form of N addition and most of the N input was retained. For 16 lake/watersheds no consistent changes in NO 3 - concentrations were found from 1982 to 1997. Simulations suggested that marked NO 3 - loss will only be manifested over extended periods. Studies at the Arbutus Watershed provided information on the role of biogeochemical and hydrological factors in affecting the spatial and temporal patterns of NO 3 - concentrations. The heterogeneous topography in the Adirondacks has generated diverse landscape features and patterns of connectivity that are especially important in regulating the temporal and spatial patterns of NO 3 - concentrations in surface waters

NPK NMR Sensor: Online Monitoring of Nitrogen, Phosphorus, and Potassium in Animal Slurry.

Science.gov (United States)

Sørensen, Morten K; Jensen, Ole; Bakharev, Oleg N; Nyord, Tavs; Nielsen, Niels Chr

2015-07-07

Knowledge of the actual content of nitrogen, phosphorus, and potassium (NPK) in animal slurry is highly important to optimize crop production and avoid environmental pollution when slurry is spread on agricultural fields. Here, we present a mobile, low-field nuclear magnetic resonance (NMR) sensor suitable for online monitoring of the NPK content in animal slurry as an alternative to crude estimates or tedious nonspecific, off-site laboratory analysis. The sensor is based on (14)N, (17)O, (31)P, and (39)K NMR in a digital NMR instrument equipped with a 1.5 T Halbach magnet for direct detection of ammonium N, total P, and K and indirect evaluation of the organic N content, covering all practical components of NPK in animal slurry. In correlation studies, the obtained NMR measurements show good agreement with reference measurements from commercial laboratories.

Charge Dynamics in near-Surface, Variable-Density Ensembles of Nitrogen-Vacancy Centers in Diamond.

Science.gov (United States)

Dhomkar, Siddharth; Jayakumar, Harishankar; Zangara, Pablo R; Meriles, Carlos A

2018-06-13

Although the spin properties of superficial shallow nitrogen-vacancy (NV) centers have been the subject of extensive scrutiny, considerably less attention has been devoted to studying the dynamics of NV charge conversion near the diamond surface. Using multicolor confocal microscopy, here we show that near-surface point defects arising from high-density ion implantation dramatically increase the ionization and recombination rates of shallow NVs compared to those in bulk diamond. Further, we find that these rates grow linearly, not quadratically, with laser intensity, indicative of single-photon processes enabled by NV state mixing with other defect states. Accompanying these findings, we observe NV ionization and recombination in the dark, likely the result of charge transfer to neighboring traps. Despite the altered charge dynamics, we show that one can imprint rewritable, long-lasting patterns of charged-initialized, near-surface NVs over large areas, an ability that could be exploited for electrochemical biosensing or to optically store digital data sets with subdiffraction resolution.

Alteration of the Carbon and Nitrogen Isotopic Composition in the Martian Surface Rocks Due to Cosmic Ray Exposure

Science.gov (United States)

Pavlov, A. A.; Pavlov, A. K.; Ostryakov, V. M.; Vasilyev, G. I.; Mahaffy, P.; Steele, A.

2014-01-01

C-13/C-12 and N-15/N-14 isotopic ratios are pivotal for our understanding of the Martian carbon cycle, history of the Martian atmospheric escape, and origin of the organic compounds on Mars. Here we demonstrate that the carbon and nitrogen isotopic composition of the surface rocks on Mars can be significantly altered by the continuous exposure of Martian surface to cosmic rays. Cosmic rays can effectively produce C-13 and N-15 isotopes via spallation nuclear reactions on oxygen atoms in various Martian rocks. We calculate that in the top meter of the Martian rocks, the rates of production of both C-13 and N-15 due to galactic cosmic rays (GCRs) exposure can vary within 1.5-6 atoms/cm3/s depending on rocks' depth and chemical composition. We also find that the average solar cosmic rays can produce carbon and nitrogen isotopes at a rate comparable to GCRs in the top 5-10 cm of the Martian rocks. We demonstrate that if the total carbon content in a surface Martian rock is <10 ppm, then the "light," potentially "biological" C-13/C-12 ratio would be effectively erased by cosmic rays over 3.5 billion years of exposure. We found that for the rocks with relatively short exposure ages (e.g., 100 million years), cosmogenic changes in N-15/N-14 ratio are still very significant. We also show that a short exposure to cosmic rays of Allan Hills 84001 while on Mars can explain its high-temperature heavy nitrogen isotopic composition (N-15/N-14). Applications to Martian meteorites and the current Mars Science Laboratory mission are discussed.

Nitrogen-doped graphene by microwave plasma chemical vapor deposition

International Nuclear Information System (INIS)

Kumar, A.; Voevodin, A.A.; Paul, R.; Altfeder, I.; Zemlyanov, D.; Zakharov, D.N.; Fisher, T.S.

2013-01-01

Rapid synthesis of nitrogen-doped, few-layer graphene films on Cu foil is achieved by microwave plasma chemical vapor deposition. The films are doped during synthesis by introduction of nitrogen gas in the reactor. Raman spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy and scanning tunneling microscopy reveal crystal structure and chemical characteristics. Nitrogen concentrations up to 2 at.% are observed, and the limit is linked to the rigidity of graphene films on copper surfaces that impedes further nitrogen substitutions of carbon atoms. The entire growth process requires only a few minutes without supplemental substrate heating and offers a promising path toward large-scale synthesis of nitrogen-doped graphene films. - Highlights: ► Rapid synthesis of nitrogen doped few layer graphene on Cu foil. ► Defect density increment on 2% nitrogen doping. ► Nitrogen doped graphene is a good protection to the copper metallic surface

Nitrogen-doped graphene by microwave plasma chemical vapor deposition

Energy Technology Data Exchange (ETDEWEB)

Kumar, A., E-mail: kumar50@purdue.edu [Birck Nanotechnolgy Center, Purdue University, West Lafayette, IN 47907 (United States); Voevodin, A.A. [Birck Nanotechnolgy Center, Purdue University, West Lafayette, IN 47907 (United States); Materials and Manufacturing Directorate, Air Force Research Laboratory, WPAFB, OH 45433 (United States); Paul, R. [Birck Nanotechnolgy Center, Purdue University, West Lafayette, IN 47907 (United States); Altfeder, I. [Materials and Manufacturing Directorate, Air Force Research Laboratory, WPAFB, OH 45433 (United States); Zemlyanov, D.; Zakharov, D.N. [Birck Nanotechnolgy Center, Purdue University, West Lafayette, IN 47907 (United States); Fisher, T.S., E-mail: tsfisher@purdue.edu [Birck Nanotechnolgy Center, Purdue University, West Lafayette, IN 47907 (United States); Materials and Manufacturing Directorate, Air Force Research Laboratory, WPAFB, OH 45433 (United States)

2013-01-01

Rapid synthesis of nitrogen-doped, few-layer graphene films on Cu foil is achieved by microwave plasma chemical vapor deposition. The films are doped during synthesis by introduction of nitrogen gas in the reactor. Raman spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy and scanning tunneling microscopy reveal crystal structure and chemical characteristics. Nitrogen concentrations up to 2 at.% are observed, and the limit is linked to the rigidity of graphene films on copper surfaces that impedes further nitrogen substitutions of carbon atoms. The entire growth process requires only a few minutes without supplemental substrate heating and offers a promising path toward large-scale synthesis of nitrogen-doped graphene films. - Highlights: ► Rapid synthesis of nitrogen doped few layer graphene on Cu foil. ► Defect density increment on 2% nitrogen doping. ► Nitrogen doped graphene is a good protection to the copper metallic surface.

Strategies for Detecting Hidden Geothermal Systems by Near-Surface Gas Monitoring

Energy Technology Data Exchange (ETDEWEB)

Lewicki, Jennifer L.; Oldenburg, Curtis M.

2004-12-15

''Hidden'' geothermal systems are those systems above which hydrothermal surface features (e.g., hot springs, fumaroles, elevated ground temperatures, hydrothermal alteration) are lacking. Emissions of moderate to low solubility gases (e.g., CO2, CH4, He) may be one of the primary near-surface signals from these systems. Detection of anomalous gas emissions related to hidden geothermal systems may therefore be an important tool to discover new geothermal resources. This study investigates the potential for CO2 detection and monitoring in the subsurface and above ground in the near-surface environment to serve as a tool to discover hidden geothermal systems. We focus the investigation on CO2 due to (1) its abundance in geothermal systems, (2) its moderate solubility in water, and (3) the wide range of technologies available to monitor CO2 in the near-surface environment. However, monitoring in the near-surface environment for CO2 derived from hidden geothermal reservoirs is complicated by the large variation in CO2 fluxes and concentrations arising from natural biological and hydrologic processes. In the near-surface environment, the flow and transport of CO2 at high concentrations will be controlled by its high density, low viscosity, and high solubility in water relative to air. Numerical simulations of CO2 migration show that CO2 concentrations can reach very high levels in the shallow subsurface even for relatively low geothermal source CO2 fluxes. However, once CO2 seeps out of the ground into the atmospheric surface layer, surface winds are effective at dispersing CO2 seepage. In natural ecological systems in the absence of geothermal gas emissions, near-surface CO2 fluxes and concentrations are primarily controlled by CO2 uptake by photosynthesis, production by root respiration, and microbial decomposition of soil/subsoil organic matter, groundwater degassing, and exchange with the atmosphere. Available technologies for monitoring CO2 in

New and Emerging Technologies for Real-Time Air and Surface Beryllium Monitoring

Energy Technology Data Exchange (ETDEWEB)

Phifer, B.E. Jr.; Churnetski, E.L.; Cooke, L.E.; Reed, J.J.; Howell, M.L.; Smith, V.D.

2001-09-01

In this study, five emerging technologies were identified for real-time monitoring of airborne beryllium: Microwave-Induced Plasma Spectroscopy (MIPS), Aerosol Beam-Focused Laser-Induced Plasma Spectroscopy (ABFLIPS), Laser-Induced Breakdown Spectroscopy (LIBS), Surfaced-Enhanced Raman Scattering (SERS) Spectroscopy, and Micro-Calorimetric Spectroscopy (CalSpec). Desired features of real-time air beryllium monitoring instrumentation were developed from the Y-12 CBDPP. These features were used as guidelines for the identification of potential technologies as well as their unique demonstrated capability to provide real-time monitoring of similar materials. However, best available technologies were considered, regardless of their ability to comply with the desired features. None of the five technologies have the capability to measure the particle size of airborne beryllium. Although reducing the total concentration of airborne beryllium is important, current literature suggests that reducing or eliminating the concentration of respirable beryllium is critical for worker health protection. Eight emerging technologies were identified for surface monitoring of beryllium. CalSpec, MIPS, SERS, LIBS, Laser Ablation, Absorptive Stripping Voltametry (ASV), Modified Inductively Coupled Plasma (ICP) Spectroscopy, and Gamma BeAST. Desired features of real-time surface beryllium monitoring were developed from the Y-12 CBDPP. These features were used as guidelines for the identification of potential technologies. However, the best available technologies were considered regardless of their ability to comply with the desired features.

A Wireless Monitoring System for Cracks on the Surface of Reactor Containment Buildings.

Science.gov (United States)

Zhou, Jianguo; Xu, Yaming; Zhang, Tao

2016-06-14

Structural health monitoring with wireless sensor networks has been increasingly popular in recent years because of the convenience. In this paper, a real-time monitoring system for cracks on the surface of reactor containment buildings is presented. Customized wireless sensor networks platforms are designed and implemented with sensors especially for crack monitoring, which include crackmeters and temperature detectors. Software protocols like route discovery, time synchronization and data transfer are developed to satisfy the requirements of the monitoring system and stay simple at the same time. Simulation tests have been made to evaluate the performance of the system before full scale deployment. The real-life deployment of the crack monitoring system is carried out on the surface of reactor containment building in Daya Bay Nuclear Power Station during the in-service pressure test with 30 wireless sensor nodes.

Transformation of nitrogenous fertilizers of surface and deep application in calcareous soil

International Nuclear Information System (INIS)

Zuo Dongfeng

1990-01-01

The transformations of 15 N labelled fertilizer N in calcareous soil were studied under greennhouse conditions. The experimental results indicate that the ratio of fixed ammonium is closely related to the methods of fertilizer application to the soil. When fertilizer N applied as deep dressing the fixation of nitrogen by clay minerals and microorganisms may markedly reduce the losses of nitrogen, but the amount of nitrogen fixed by the clay minerals and that by microorganisms showed negative correlation (r = -0.9185 ** ). The more the amount of fixed nitrogen by clay minerals, the less by microorganisms. No obvious interrelation between the residual utilization of urea, ammonium bicarbonate, ammonium sulfate and the ammount of nitrogen fixed by organisms can be observed, but the residual utilization of these fertilizers by the succeeding crop has been related to the total amount of mineral nitrogen

Hierarchical nitrogen-doped porous carbon with high surface area derived from endothelium corneum gigeriae galli for high-performance supercapacitor

International Nuclear Information System (INIS)

Hong, Xiaoting; Hui, K.S.; Zeng, Zhi; Hui, K.N.; Zhang, Luojiang; Mo, Mingyue; Li, Min

2014-01-01

Highlights: • Porous carbons were prepared using endothelium corneum gigeriae galli as precursor. • Surface and structural properties strongly depend on carbonization temperatures. • Resultant carbons possess nitrogen heteroatom and high surface areas. • ECGG-900 sample exhibits excellent electrochemical capacitive performances. - Abstract: Endothelium corneum gigeriae galli derived 3D hierarchical nitrogen-doped porous carbon was for the first time prepared by preliminary carbonization at 450 °C and final KOH activation at high temperatures. The surface and structural properties of the as-synthesized samples are analyzed with Brunauer–Emmett–Teller surface analyzer apparatus, X-Ray Diffractometer, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectrometer. The electrochemical performances are analyzed by cyclic voltammetry, galvanostatic charge/discharge cycling and electrochemical impedance spectroscopy. The obtained results show that the sample carbonized at 900 °C possesses the SSA of 2149.9 m 2 g −1 , average micropore diameter of 1.78 nm, and exhibits the highest initial specific capacitance of 198.0 F g −1 at current density of 1 A g −1 in 6 M KOH solution. It retains good specific capacitance retention of 91.6% after 3000 charge/discharge cycles at current density of 2 A g −1

Deactivation of molybdate catalysts by nitrogen bases

Energy Technology Data Exchange (ETDEWEB)

Furimsky, E.

1982-10-01

Nitrogen bases present in petroleum deactivate the surface of molybdate catalysts. The detrimental effect is attributed either to interactions of the bases with Lewis sites via unpaired electrons on nitrogen or to their ability to remove proton from the surface. The later effect results in a decrease of concentration of Bronsted sites known to be active in catalytic reactions. This enhances rate of coke forming reactions. Resistence of molybdate catalysts to coke formation depends on the form and redistribution of active ingredients on the surface. This can be effected by conditions applied during preparation and pretreatment of the catalysts. Processing parameters used during catalytic hydrotreatment are also important; i.e., the coke formation is slow under conditions ensuring high rate of removal of basic nitrogen containing compounds.

Computer simulation on generation of nitrogen clusters

International Nuclear Information System (INIS)

Yano, Katsuki

1975-01-01

Numerical calculations were made for supersonic flow of nitrogen gas accompanied by homogeneous condensation through a nozzle. It was demonstrated that nitrogen clusters are generated in a nozzle and, by comparing the experimental results, the surface tension of the clusters was obtained at 0.68 sigmasub(infinity) and the condensation coefficient at 0.1--0.2, where sigmasub(infinity) is the surface tension of plane surface of liquid nitrogen. Numerical results calculated with the above values show that large clusters are produced under conditions of high degree of saturation and high temperature in a gas reservoir, and also when a nozzle with small open angle and/or large throat is used. These results agree well with the experimental results. (auth.)

[Progress in inversion of vegetation nitrogen concentration by hyperspectral remote sensing].

Science.gov (United States)

Wang, Li-Wen; Wei, Ya-Xing

2013-10-01

Nitrogen is the necessary element in life activity of vegetation, which takes important function in biosynthesis of protein, nucleic acid, chlorophyll, and enzyme etc, and plays a key role in vegetation photosynthesis. The technology about inversion of vegetation nitrogen concentration by hyperspectral remote sensing has been the research hotspot since the 70s of last century. With the development of hyperspectral remote sensing technology in recent years, the advantage of spectral bands subdivision in a certain spectral region provides the powerful technology measure for correlative spectral characteristic research on vegetation nitrogen. In the present paper, combined with the newest research production about monitoring vegetation nitrogen concentration by hyperspectral remote sensing published in main geography science literature in recent several years, the principle and correlated problem about monitoring vegetation nitrogen concentration by hyperspectral remote sensing were introduced. From four aspects including vegetation nitrogen spectral index, vegetation nitrogen content inversion based on chlorophyll index, regression model, and eliminating influence factors to inversion of vegetation nitrogen concentration, main technology methods about inversion of vegetation nitrogen concentration by hyperspectral remote sensing were detailedly introduced. Correlative research conclusions were summarized and analyzed, and research development trend was discussed.

Long-range alpha detection applied to soil surface monitoring

International Nuclear Information System (INIS)

Caress, R.W.; Allander, K.S.; Bounds, J.A.; Catlett, M.M.; MacArthur, D.W.; Rutherford, D.A.

1992-01-01

The long-range alpha detection (LRAD) technique depends on the detection of ion pairs generated by alpha particles losing energy in air rather than on detection of the alpha particles themselves. Typical alpha particles generated by uranium will travel less than 3 cm in air. In contrast, the ions have been successfully detected many inches or feet away from the contamination. Since LRAD detection systems are sensitive to all ions simultaneously, large LRAD soil surface monitors (SSMS) can be used to collect all of the ions from a large sample. The LRAD SSMs are designed around the fan-less LRAD detector. In this case a five-sided box with an open bottom is placed on the soil surface. Ions generated by alpha decays on the soil surface are collected on a charged copper plate within the box. These ions create a small current from the plate to ground which is monitored with a sensitive electrometer. The current measured is proportional to the number of ions in the box, which is, in turn, proportional to the amount of alpha contamination on the surface of the soil. This report includes the design and construction of a 1-m by 1-m SSM as well as the results of a study at Fernald, OH, as part of the Uranium in Soils Integrated Demonstration

Optical surface scanning for respiratory motion monitoring in radiotherapy: a feasibility study

DEFF Research Database (Denmark)

Bekke, Susanne Lise; Mahmood, Faisal; Helt-Hansen, Jakob

2014-01-01

Purpose. We evaluated the feasibility of a surface scanning system (Catalyst) for respiratory motion monitoring of breast cancer patients treated with radiotherapy in deep inspiration breath-hold (DIBH). DIBH is used to reduce the radiation dose to the heart and lung. In contrast to RPM, a compet......Purpose. We evaluated the feasibility of a surface scanning system (Catalyst) for respiratory motion monitoring of breast cancer patients treated with radiotherapy in deep inspiration breath-hold (DIBH). DIBH is used to reduce the radiation dose to the heart and lung. In contrast to RPM...... and 3: the Quasar phantom was used to study if the angle of the monitored surface affects the amplitude of the recorded signal. Results. Experiment 1: we observed comparable period estimates for both systems. The amplitudes were 8 ± 0.1 mm (Catalyst) and 4.9 ± 0.1 mm (RPM). Independent check with in...... 1. Experiment 3: an increased (fixed) surface angle during breathing motion resulted in an overestimated amplitude with RPM, while the amplitude estimated by Catalyst was unaffected. Conclusion. Our study showed that Catalyst can be used as a better alternative to the RPM. With Catalyst...

Genomics and ecophysiology of heterotrophic nitrogen fixing bacteria isolated from estuarine surface water

DEFF Research Database (Denmark)

Bentzon-Tilia, Mikkel; Severin, Ina; Hansen, Lars H.

2015-01-01

The ability to reduce atmospheric nitrogen (N2) to ammonia, known as N2 fixation, is a widely distributed trait among prokaryotes that accounts for an essential input of new N to a multitude of environments. Nitrogenase reductase gene (nifH) composition suggests that putative N2-fixing heterotrop......The ability to reduce atmospheric nitrogen (N2) to ammonia, known as N2 fixation, is a widely distributed trait among prokaryotes that accounts for an essential input of new N to a multitude of environments. Nitrogenase reductase gene (nifH) composition suggests that putative N2-fixing...... heterotrophic organisms are widespread in marine bacterioplankton, but their autecology and ecological significance are unknown. Here, we report genomic and ecophysiology data in relation to N2 fixation by three environmentally relevant heterotrophic bacteria isolated from Baltic Sea surface water: Pseudomonas...... liter-1, presumably accommodated through aggregate formation. Glucose stimulated N2 fixation in general, and reactive N repressed N2 fixation, except that ammonium (NH4 ) stimulated N2 fixation in R. palustris BAL398, indicating the use of nitrogenase as an electron sink. The lack of correlations...

Nitrogen bonding in aluminum oxynitride films

Energy Technology Data Exchange (ETDEWEB)

Wang, Paul W., E-mail: pwang@bradley.edu [Department of Physics, Bradley University, 1501 W. Bradley Ave., Peoria, IL 61625 (United States); Hsu, Jin-Cherng [Department of Physics, Fu Jen Catholic University, Hsinchuang, Taipei Hsien 24205, Taiwan (China); Lin, Yung-Hsin; Chen, Huang-Lu [Graduate Institute of Applied Science and Engineering, Fu Jen Catholic University, Hsinchuang, Taipei Hsien 24205, Taiwan (China)

2010-04-15

Assignment of oxidation states of N{sub 1s} in XPS spectra of aluminum oxynitride by curve fitting is difficult. The XPS curve fitting was previously discussed in the paper published in J. Non-Cryst. Solids, 224 (1998) 31, in which O{sub 1s} photoelectrons from GeO{sub 2} glass were used to illustrate how to fit the XPS spectra. Three different ways were pointed out to eliminate the ambiguity caused by curve fitting such as comparing the data to data from standard samples, investigating the continuous surface modifications caused by slowly sputtering the surface, and monitoring the continuous surface modifications due to gradual increases in surface species under heating, cooling, or irradiation. Our recent work in aluminum oxynitride films provides another example of how to fit the XPS spectra of N{sub 1s} by three different oxidation states of N{sup +}, N{sup 2+}, and N{sup 3+}, by comparison of the measured data to data from previously published results, and by the gradual changes of spectra as functions of the oxygen contents in the films. Three oxidation states in different nitrogen bonding in the aluminum oxynitride, AlO{sub 2}N, Al{sub 2}O{sub 5}N{sub 2}, and AlO{sub 3}N, were clearly deduced.

Analyzer for measurement of nitrogen oxide concentration by ozone content reduction in gas using solid state chemiluminescent sensor

Science.gov (United States)

Chelibanov, V. P.; Ishanin, G. G.; Isaev, L. N.

2014-05-01

Role of nitrogen oxide in ambient air is described and analyzed. New method of nitrogen oxide concentration measurement in gas phase is suggested based on ozone concentration measurement with titration by nitrogen oxide. Research of chemiluminescent sensor composition is carried out on experimental stand. The sensor produced on the base of solid state non-activated chemiluminescent composition is applied as ozone sensor. Composition is put on the surface of polymer matrix with developed surface. Sensor compositions includes gallic acid with addition of rodamine-6G. Model of interaction process between sensor composition and ozone has been developed, main products appeared during reaction are identified. The product determining the speed of luminescense appearance is found. This product belongs to quinone class. Then new structure of chemiluminescent composition was suggested, with absence of activation period and with high stability of operation. Experimental model of gas analyzer was constructed and operation algorithm was developed. It was demonstrated that developed NO measuring instrument would be applied for monitoring purposes of ambient air. This work was partially financially supported by Government of Russian Federation, Grant 074-U01

Application of nitrogen plasma immersion ion implantation to titanium nasal implants with nanonetwork surface structure

Energy Technology Data Exchange (ETDEWEB)

Sun, Ying-Sui; Yang, Wei-En [Department of Dentistry, National Yang-Ming University, Taipei 112, Taiwan (China); Zhang, Lan [State Key Laboratory for Mechanical Behavior of Materials, Xi' an Jiaotong University, Xi' an 710049 (China); Zhu, Hongqin [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Lan, Ming-Ying [Division of Rhinology, Department of Otolaryngology Head and Neck Surgery, Taipei Veterans General Hospital, Taipei 112, Taiwan and School of Medicine, National Yang-Ming University, Taipei 112, Taiwan (China); Lee, Sheng-Wei [Institute of Materials Science and Engineering, National Central University, Taoyuan 320, Taiwan (China); Huang, Her-Hsiung, E-mail: hhhuang@ym.edu.tw [Department of Dentistry, National Yang-Ming University, Taipei 112, Taiwan (China); Institute of Oral Biology, National Yang-Ming University, Taipei 112, Taiwan (China); Graduate Institute of Basic Medical Science, China Medical University, Taichung 404, Taiwan (China); Department of Medical Research, China Medical University Hospital, Taichung 407, Taiwan (China); Department of Bioinformatics and Medical Engineering, Asia University, Taichung 413, Taiwan (China); Department of Stomatology, Taipei Veterans General Hospital, Taipei 112, Taiwan (China)

2016-07-15

In nasal reconstruction, the response of cells to titanium (Ti) implants is mainly determined by surface features of the implant. In a pilot study, the authors applied electrochemical anodization to Ti surfaces in an alkaline solution to create a network of nanoscale surface structures. This nanonetwork was intended to enhance the responses of primary human nasal epithelial cell (HNEpC) to the Ti surface. In this study, the authors then treated the anodized, nanonetwork-structured Ti surface using nitrogen plasma immersion ion implantation (NPIII) in order to further improve the HNEpC response to the Ti surface. Subsequently, surface characterization was performed to elucidate morphology, roughness, wettability, and chemistry of specimens. Cytotoxicity, blood, and HNEpC responses were also evaluated. Our results demonstrate that NPIII treatment led to the formation of a noncytotoxic TiN-containing thin film (thickness <100 nm) on the electrochemically anodized Ti surface with a nanonetwork-structure. NPIII treatment was shown to improve blood clotting and the adhesion of platelets to the anodized Ti surface as well as the adhesion and proliferation of hNEpC. This research spreads our understanding of the fact that a TiN-containing thin film, produced using NPIII treatment, could be used to improve blood and HNEpC responses to anodized, nanonetwork-structured Ti surfaces in nasal implant applications.

Conceptual design for relocation of the underground monitoring systems to ground surface

International Nuclear Information System (INIS)

Toya, Naruhisa; Ogawa, Ken; Iwatsuki, Teruki; Ohnuki, Kenji

2015-09-01

One of the major subjects of the ongoing geoscientific research program, the Mizunami Underground Research Laboratory (MIU) Project in the Tono area, central Japan, is accumulation of knowledge on a recovery of the geological environment during and after the facility closure. Then it is necessary to plan the observation system which can be use of after the backfill of research tunnels. The main purpose of this report is contribution to the detailed design for relocation of the underground monitoring systems to ground surface. We discussed the restriction and requirement for the underground monitoring systems which can be use of after the backfill. Furthermore, we made the conceptual design for relocation of the current underground monitoring systems to ground surface. (author)

Interaction of the Helium, Hydrogen, Air, Argon, and Nitrogen Bubbles with Graphite Surface in Water.

Science.gov (United States)

Bartali, Ruben; Otyepka, Michal; Pykal, Martin; Lazar, Petr; Micheli, Victor; Gottardi, Gloria; Laidani, Nadhira

2017-05-24

The interaction of the confined gas with solid surface immersed in water is a common theme of many important fields such as self-cleaning surface, gas storage, and sensing. For that reason, we investigated the gas-graphite interaction in the water medium. The graphite surface was prepared by mechanical exfoliation of highly oriented pyrolytic graphite (HOPG). The surface chemistry and morphology were studied by X-ray photoelectron spectroscopy, profilometry, and atomic force microscopy. The surface energy of HOPG was estimated by contact angle measurements using the Owens-Wendt method. The interaction of gases (Ar, He, H 2 , N 2 , and air) with graphite was studied by a captive bubble method, in which the gas bubble was in contact with the exfoliated graphite surface in water media. The experimental data were corroborated by molecular dynamics simulations and density functional theory calculations. The surface energy of HOPG equaled to 52.8 mJ/m 2 and more of 95% of the surface energy was attributed to dispersion interactions. The results on gas-surface interaction indicated that HOPG surface had gasphilic behavior for helium and hydrogen, while gasphobic behavior for argon and nitrogen. The results showed that the variation of the gas contact angle was related to the balance between the gas-surface and gas-gas interaction potentials. For helium and hydrogen the gas-surface interaction was particularly high compared to gas-gas interaction and this promoted the favorable interaction with graphite surface.

Nutrient concentrations in leachate and runoff from dairy cattle lots with different surface materials

Science.gov (United States)

Nitrogen (N) and phosphorus (P) loss from agriculture persists as a water quality issue, and outdoor cattle lots can have a high loss potential. We monitored hydrology and nutrient concentrations in leachate and runoff from dairy heifer lots constructed with three surface materials (soil, sand, bark...

Effect of nitrogen plasma afterglow on the surface charge effect resulted during XPS surface analysis of amorphous carbon nitride thin films

Science.gov (United States)

Kayed, Kamal

2018-06-01

The aim of this paper is to investigate the relationship between the micro structure and the surface charge effect resulted during XPS surface analysis of amorphous carbon nitride thin films prepared by laser ablation method. The study results show that the charge effect coefficient (E) is not just a correction factor. We found that the changes in this coefficient value due to incorporation of nitrogen atoms into the carbon network are related to the spatial configurations of the sp2 bonded carbon atoms, order degree and sp2 clusters size. In addition, results show that the curve E vs. C(sp3)-N is a characteristic curve of the micro structure. This means that using this curve makes it easy to sorting the samples according to the micro structure (hexagonal rings or chains).

Application Of The SPV-based Surface Lifetime Technique To In-Line Monitoring Of Surface Cu Contamination

Science.gov (United States)

D'Amico, John; Savtchouk, Alexandre; Wilson, Matthew; Kim, Chul Hong; Yoo, Hyung Won; Lee, Chang Hwan; Kim, Tae Kyoung; Son, Sang Hoon

2009-09-01

Implementation of Cu interconnects into Silicon Integrated Circuits (IC's) has been instrumental in the continuing improvement of IC device performance. Copper as a well known Gate Oxide Integrity (GOI) killer [1, 2] requires extensive protocols to minimize the possibility of cross contamination. Despite such protocols the risk for cross contamination exists, and consequently there is the need for in-line Cu cross-contamination detection metrology. Preferably the metrology will be non-destructive, fast, and capable of mapping on product wafers. Up to now the most common approaches for monitoring Cu contamination in IC fabrication lines either measure Cu in the bulk Si, which is not applicable to Cu cross-contamination monitoring because Back-End-of-the-Line thermal budgets restrict the ability to diffuse the surface Cu into the bulk Si; or the techniques are not optimal for in-line monitoring due to their destructive, time-consuming, or costly nature. In this work we demonstrate for the first time the application of the ac-Surface Photo Voltage (ac-SPV) surface lifetime approach [3] to in-line, full wafer coverage mapping of low level (metrology system. Furthermore, because the metrology is non-contact (utilizing edge-grip handling) and non-destructive, it is directly applicable to measurement of production wafers. In-line fab data acquired using this metrology is presented and compared to data from Inductively Coupled Plasma Mass Spectroscopy (ICP-MS).

A Runway Surface Monitor using Internet of Things

Science.gov (United States)

Troiano, Amedeo; Pasero, Eros

2014-05-01

The monitoring of runway surfaces, for the detection of ice formation or presence of water, is an important issue for reducing maintenance costs and improving traffic safety. An innovative sensor was developed to detect the presence of ice or water on its surface, and its repeatability, stability and reliability were assessed in different simulations and experiments, performed both in laboratory and in the field. Three sensors were embedded in the runway of the Turin-Caselle airport, in the north-west of Italy, to check the state of its surface. Each sensor was connected to a GPRS modem to send the collected data to a common database. The entire system was installed about three years ago, and up to now it shows correct work and automatic reactivation after malfunctions without any external help. The state of the runway surface is virtual represented in an internet website, using the Internet of Things features and opening new scenarios.

Discrete impurity band from surface danging bonds in nitrogen and phosphorus doped SiC nanowires

Science.gov (United States)

Li, Yan-Jing; Li, Shu-Long; Gong, Pei; Li, Ya-Lin; Cao, Mao-Sheng; Fang, Xiao-Yong

2018-04-01

The electronic structure and optical properties of the nitrogen and phosphorus doped silicon carbide nanowires (SiCNWs) are investigated using first-principle calculations based on density functional theory. The results show doping can change the type of the band gap and improve the conductivity. However, the doped SiCNWs form a discrete impurity levels at the Fermi energy, and the dispersion degree decreases with the diameter increasing. In order to reveal the root of this phenomenon, we hydrogenated the doped SiCNWs, found that the surface dangling bonds were saturated, and the discrete impurity levels are degeneracy, which indicates that the discrete impurity band of the doped SiCNWs is derived from the dangling bonds. The surface passivation can degenerate the impurity levels. Therefore, both doping and surface passivation can better improve the photoelectric properties of the SiCNWs. The result can provide additional candidates in producing nano-optoelectronic devices.

Nuclear electronic components of surface contamination monitor based on multi-electrode proportional counter

International Nuclear Information System (INIS)

Du Xiangyang; Zhang Yong; Han Shuping; Rao Xianming; Fang Jintu

2001-01-01

The nuclear electronic components applying in Portal Monitor and Hands and Feet Surface Contamination Monitor were based on modern integrated circuit are introduced. The detailed points in circuit design and manufacturing technique are analyzed

Nitrogen fixation in denitrified marine waters.

Directory of Open Access Journals (Sweden)

Camila Fernandez

Full Text Available Nitrogen fixation is an essential process that biologically transforms atmospheric dinitrogen gas to ammonia, therefore compensating for nitrogen losses occurring via denitrification and anammox. Currently, inputs and losses of nitrogen to the ocean resulting from these processes are thought to be spatially separated: nitrogen fixation takes place primarily in open ocean environments (mainly through diazotrophic cyanobacteria, whereas nitrogen losses occur in oxygen-depleted intermediate waters and sediments (mostly via denitrifying and anammox bacteria. Here we report on rates of nitrogen fixation obtained during two oceanographic cruises in 2005 and 2007 in the eastern tropical South Pacific (ETSP, a region characterized by the presence of coastal upwelling and a major permanent oxygen minimum zone (OMZ. Our results show significant rates of nitrogen fixation in the water column; however, integrated rates from the surface down to 120 m varied by ∼30 fold between cruises (7.5±4.6 versus 190±82.3 µmol m(-2 d(-1. Moreover, rates were measured down to 400 m depth in 2007, indicating that the contribution to the integrated rates of the subsurface oxygen-deficient layer was ∼5 times higher (574±294 µmol m(-2 d(-1 than the oxic euphotic layer (48±68 µmol m(-2 d(-1. Concurrent molecular measurements detected the dinitrogenase reductase gene nifH in surface and subsurface waters. Phylogenetic analysis of the nifH sequences showed the presence of a diverse diazotrophic community at the time of the highest measured nitrogen fixation rates. Our results thus demonstrate the occurrence of nitrogen fixation in nutrient-rich coastal upwelling systems and, importantly, within the underlying OMZ. They also suggest that nitrogen fixation is a widespread process that can sporadically provide a supplementary source of fixed nitrogen in these regions.

Nitrogen Fixation in Denitrified Marine Waters

Science.gov (United States)

Fernandez, Camila; Farías, Laura; Ulloa, Osvaldo

2011-01-01

Nitrogen fixation is an essential process that biologically transforms atmospheric dinitrogen gas to ammonia, therefore compensating for nitrogen losses occurring via denitrification and anammox. Currently, inputs and losses of nitrogen to the ocean resulting from these processes are thought to be spatially separated: nitrogen fixation takes place primarily in open ocean environments (mainly through diazotrophic cyanobacteria), whereas nitrogen losses occur in oxygen-depleted intermediate waters and sediments (mostly via denitrifying and anammox bacteria). Here we report on rates of nitrogen fixation obtained during two oceanographic cruises in 2005 and 2007 in the eastern tropical South Pacific (ETSP), a region characterized by the presence of coastal upwelling and a major permanent oxygen minimum zone (OMZ). Our results show significant rates of nitrogen fixation in the water column; however, integrated rates from the surface down to 120 m varied by ∼30 fold between cruises (7.5±4.6 versus 190±82.3 µmol m−2 d−1). Moreover, rates were measured down to 400 m depth in 2007, indicating that the contribution to the integrated rates of the subsurface oxygen-deficient layer was ∼5 times higher (574±294 µmol m−2 d−1) than the oxic euphotic layer (48±68 µmol m−2 d−1). Concurrent molecular measurements detected the dinitrogenase reductase gene nifH in surface and subsurface waters. Phylogenetic analysis of the nifH sequences showed the presence of a diverse diazotrophic community at the time of the highest measured nitrogen fixation rates. Our results thus demonstrate the occurrence of nitrogen fixation in nutrient-rich coastal upwelling systems and, importantly, within the underlying OMZ. They also suggest that nitrogen fixation is a widespread process that can sporadically provide a supplementary source of fixed nitrogen in these regions. PMID:21687726

Structural characteristics of surface-functionalized nitrogen-doped diamond-like carbon films and effective adjustment to cell attachment

Science.gov (United States)

Liu, Ai-Ping; Liu, Min; Yu, Jian-Can; Qian, Guo-Dong; Tang, Wei-Hua

2015-05-01

Nitrogen-doped diamond-like carbon (DLC:N) films prepared by the filtered cathodic vacuum arc technology are functionalized with various chemical molecules including dopamine (DA), 3-Aminobenzeneboronic acid (APBA), and adenosine triphosphate (ATP), and the impacts of surface functionalities on the surface morphologies, compositions, microstructures, and cell compatibility of the DLC:N films are systematically investigated. We demonstrate that the surface groups of DLC:N have a significant effect on the surface and structural properties of the film. The activity of PC12 cells depends on the particular type of surface functional groups of DLC:N films regardless of surface roughness and wettability. Our research offers a novel way for designing functionalized carbon films as tailorable substrates for biosensors and biomedical engineering applications. Project supported by the National Natural Science Foundation of China (Grant Nos. 51272237, 51272231, and 51010002) and the China Postdoctoral Science Foundation (Grant Nos. 2012M520063, 2013T60587, and Bsh1201016).

Assessing total nitrogen in surface-water samples--precision and bias of analytical and computational methods

Science.gov (United States)

Rus, David L.; Patton, Charles J.; Mueller, David K.; Crawford, Charles G.

2013-01-01

The characterization of total-nitrogen (TN) concentrations is an important component of many surface-water-quality programs. However, three widely used methods for the determination of total nitrogen—(1) derived from the alkaline-persulfate digestion of whole-water samples (TN-A); (2) calculated as the sum of total Kjeldahl nitrogen and dissolved nitrate plus nitrite (TN-K); and (3) calculated as the sum of dissolved nitrogen and particulate nitrogen (TN-C)—all include inherent limitations. A digestion process is intended to convert multiple species of nitrogen that are present in the sample into one measureable species, but this process may introduce bias. TN-A results can be negatively biased in the presence of suspended sediment, and TN-K data can be positively biased in the presence of elevated nitrate because some nitrate is reduced to ammonia and is therefore counted twice in the computation of total nitrogen. Furthermore, TN-C may not be subject to bias but is comparatively imprecise. In this study, the effects of suspended-sediment and nitrate concentrations on the performance of these TN methods were assessed using synthetic samples developed in a laboratory as well as a series of stream samples. A 2007 laboratory experiment measured TN-A and TN-K in nutrient-fortified solutions that had been mixed with varying amounts of sediment-reference materials. This experiment identified a connection between suspended sediment and negative bias in TN-A and detected positive bias in TN-K in the presence of elevated nitrate. A 2009–10 synoptic-field study used samples from 77 stream-sampling sites to confirm that these biases were present in the field samples and evaluated the precision and bias of TN methods. The precision of TN-C and TN-K depended on the precision and relative amounts of the TN-component species used in their respective TN computations. Particulate nitrogen had an average variability (as determined by the relative standard deviation) of 13

Nitrogen content, 15N natural abundance and biomass of the two pleurocarpous mosses Pleurozium schreberi (Brid.) Mitt. and Scleropodium purum (Hedw.) Limpr. in relation to atmospheric nitrogen deposition

International Nuclear Information System (INIS)

Solga, A.; Burkhardt, J.; Zechmeister, H.G.; Frahm, J.-P.

2005-01-01

The suitability of the two pleurocarpous mosses Pleurozium schreberi and Scleropodium purum for assessing spatial variation in nitrogen deposition was investigated. Sampling was carried out at eight sites in the western part of Germany with bulk deposition rates ranging between 6.5 and 18.5 kg N ha -1 yr -1 . In addition to the effect of deposition on the nitrogen content of the two species, its influence on 15 N natural abundance (δ 15 N values) and on productivity was examined. Annual increases of the mosses were used for all analyses. Significant relationships between bulk N deposition and nitrogen content were obtained for both species; δ 15 N-values reflected the ratio of NH 4 -N to NO 3 -N in deposition. A negative effect of nitrogen input on productivity, i.e. decreasing biomass per area with increasing N deposition due to a reduction of stem density, was particularly evident with P. schreberi. Monitoring of N deposition by means of mosses is considered an important supplement to existing monitoring programs. It makes possible an improved spatial resolution, and thus those areas that receive high loads of nitrogen are more easily discernible. - Mosses are useful as monitors of nitrogen deposition

Effects of geographical location and land use on atmospheric deposition of nitrogen in the State of Connecticut

International Nuclear Information System (INIS)

Luo, Yuzhou; Yang, Xiusheng; Carley, Robert J.; Perkins, Christopher

2003-01-01

High ambient concentrations of tropospheric nitrogen and dry deposition flux were found in urban areas. - A network of eight monitoring stations was established to study the atmospheric nitrogen concentration and deposition in the State of Connecticut. The stations were classified into urban, rural, coastal and inland categories to represent the geographical location and land use characteristics surrounding the monitoring sites. Nitrogen species including nitrate, ammonium, nitric acid vapor and organic nitrogen in the air and precipitation were collected, analyzed and used to infer nitrogen concentrations and dry and wet deposition flux densities for the sampling period from 1997 through 1999, with independently collected meteorological data. Statistical analyses were conducted to evaluate the spatial variations of atmospheric concentration and deposition fluxes of total nitrogen in Connecticut. A slightly higher atmospheric concentration of total nitrogen was observed along the Connecticut coastline of Long Island Sound compared to inland areas, while the differences of nitrogen deposition fluxes were insignificant between coastal and inland sites. The land use characteristics surrounding the monitoring sites had profound effects on the atmospheric nitrogen concentration and dry deposition flux. The ambient nitrogen concentration over the four urban sites was averaged 38.9% higher than that over the rural sites, resulting a 58.0% higher dry deposition flux in these sites compared to their rural counterparts. The local industrial activities and traffic emissions of nitrogen at urban areas had significant effects on the spatial distribution of atmospheric nitrogen concentration and dry deposition flux in the State. Wet and total deposition fluxes appeared to be invariant between the monitoring sites, except for high flux densities measured at Old Greenwich, a monitoring station near to and downwind of the New York and New Jersey industrial complexes

Simple, sensitive nitrogen analyzer based on pulsed miniplasma source emission spectrometry

International Nuclear Information System (INIS)

Jin Zhe; Duan Yixiang

2003-01-01

The development of pulsed miniplasma source emission spectrometry for trace nitrogen determination in inert gases is described in this article. The instrument consists of a pulsed miniplasma source generated by an in-house fabricated portable high-voltage supply, an optical beam collection system, an integrated small spectrometer with a charge-coupled-device detector, an interface card, and a notebook computer for controlling spectrometer parameters and signal processing. Trace nitrogen in the inert gases, such as helium and argon, was determined by monitoring the emission intensities from nitrogen molecules at 357 and 337 nm. The analytical performance was examined under various experimental conditions. The system has a detection limit of about 15 ppb (v/v) for nitrogen in helium with a relative standard deviation of 1.5%. The newly developed instrument offers a simple, low-cost, and sensitive method for continuously monitoring trace nitrogen in high-purity inert gases

Synthesis of biocompatible and highly photoluminescent nitrogen doped carbon dots from lime: Analytical applications and optimization using response surface methodology

Energy Technology Data Exchange (ETDEWEB)

Barati, Ali [Faculty of Chemistry, Institute for Advanced Studies in Basic Sciences, Zanjan (Iran, Islamic Republic of); Shamsipur, Mojtaba, E-mail: mshamsipur@yahoo.com [Department of Chemistry, Razi University, Kermanshah (Iran, Islamic Republic of); Arkan, Elham [Nano Drug Delivery Research Center Kermanshah University of Medical Sciences, Kermanshah (Iran, Islamic Republic of); Hosseinzadeh, Leila [Novel Drug Delivery Research Center, Faculty of Pharmacy, Kermanshah University of Medical Sciences, Kermanshah (Iran, Islamic Republic of); Abdollahi, Hamid, E-mail: abd@iasbs.ac.ir [Faculty of Chemistry, Institute for Advanced Studies in Basic Sciences, Zanjan (Iran, Islamic Republic of)

2015-02-01

Herein, a facile hydrothermal treatment of lime juice to prepare biocompatible nitrogen-doped carbon quantum dots (N-CQDs) in the presence of ammonium bicarbonate as a nitrogen source has been presented. The resulting N-CQDs exhibited excitation and pH independent emission behavior; with the quantum yield (QY) up to 40%, which was several times greater than the corresponding value for CQDs with no added nitrogen source. The N-CQDs were applied as a fluorescent probe for the sensitive and selective detection of Hg{sup 2+} ions with a detection limit of 14 nM. Moreover, the cellular uptake and cytotoxicity of N-CQDs at different concentration ranges from 0.0 to 0.8 mg/ml were investigated by using PC12 cells as a model system. Response surface methodology was used for optimization and systematic investigation of the main variables that influence the QY, including reaction time, reaction temperature, and ammonium bicarbonate weight. - Highlights: • High fluorescent N-doped CQDs from lime juice have been prepared. • Response surface methodology was used to optimize and model the main factors. • N-doped CQDs were used in the selective and sensitive detection of Hg(II). • The biocompatibility of prepared N-doped CQDs was conformed using PC12 cells.

Manipulating and Monitoring On-Surface Biological Reactions by Light-Triggered Local pH Alterations.

Science.gov (United States)

Peretz-Soroka, Hagit; Pevzner, Alexander; Davidi, Guy; Naddaka, Vladimir; Kwiat, Moria; Huppert, Dan; Patolsky, Fernando

2015-07-08

Significant research efforts have been dedicated to the integration of biological species with electronic elements to yield smart bioelectronic devices. The integration of DNA, proteins, and whole living cells and tissues with electronic devices has been developed into numerous intriguing applications. In particular, the quantitative detection of biological species and monitoring of biological processes are both critical to numerous areas of medical and life sciences. Nevertheless, most current approaches merely focus on the "monitoring" of chemical processes taking place on the sensing surfaces, and little efforts have been invested in the conception of sensitive devices that can simultaneously "control" and "monitor" chemical and biological reactions by the application of on-surface reversible stimuli. Here, we demonstrate the light-controlled fine modulation of surface pH by the use of photoactive molecularly modified nanomaterials. Through the use of nanowire-based FET devices, we showed the capability of modulating the on-surface pH, by intensity-controlled light stimulus. This allowed us simultaneously and locally to control and monitor pH-sensitive biological reactions on the nanodevices surfaces, such as the local activation and inhibition of proteolytic enzymatic processes, as well as dissociation of antigen-antibody binding interactions. The demonstrated capability of locally modulating the on-surface effective pH, by a light stimuli, may be further applied in the local control of on-surface DNA hybridization/dehybridization processes, activation or inhibition of living cells processes, local switching of cellular function, local photoactivation of neuronal networks with single cell resolution and so forth.

Characterization of transfer layers on steel surfaces sliding against diamondlike carbon in dry nitrogen

Energy Technology Data Exchange (ETDEWEB)

Erdemir, A.; Bindal, C.; Pagan, J. [Argonne National Lab., IL (United States); Wilbur, P. [Colorado State Univ., Fort Collins, CO (United States). Dept. of Mechanical Engineering

1995-03-01

Transfer layers on sliding steel surfaces play important roles in tribological performance of diamondlike carbon films. This study investigated the nature of transfer layers formed on M50 balls during sliding against diamondlike carbon (DLC) films (1.5 {mu}m thick) prepared by ion-beam deposition. Long-duration sliding tests were performed with steel balls sliding against the DLC coatings in dry nitrogen at room temperature and zero humidity. Test results indicated that the friction coefficients of test pairs were initially 0.12 but decreased steadily with sliding distance to 0.02-0.03 and remained constant throughout the tests, which lasted for more than 250,000 sliding cycles (30 km). This low-friction regime appeared to coincide with the formation of a carbon-rich transfer layer on the sliding surfaces of M50 balls. Micro-laser-Raman spectroscopy and electron microscopy were used to elucidate the structure and chemistry of these transfer layers and to reveal their possible role in the wear and friction behavior of DLC-coated surfaces.

Nitrogen Dioxide Trend over the United States: the View from the Ground, the View from Space

Science.gov (United States)

Lamsal, Lok N.; Duncan, Bryan N.; Yoshida, Yasuko; Krotkov, Nickolay A.

2014-01-01

Emissions of nitrogen oxides (NOx) are decreasing over the US due to environmental policies and technological change. We use observations of tropospheric nitrogen dioxide (NO2) columns from the Ozone Monitoring Instrument (OMI) satellite instrument and surface NO2 in-situ measurements from the air quality system (AQS) to quantify the trends, and to establish the relationship between the trends in tropospheric column and surface concentration. Both observations show substantial downward trends from 2005 to 2013, with an average reduction of 35 percent according to OMI and 38 percent according to AQS. The annual reduction rates are largest in 2005-2009: -6.2 percent per year and -7 percent per year observed by OMI and AQS, respectively. We examine various factors affecting the estimated trend in OMI NO2 columns and in-situ NO2 observations. An improved understanding of trend offers valuable insights about effectiveness of emission reduction regulations on state and federal level.

U-tube based near-surface environmental monitoring in the Shenhua carbon dioxide capture and storage (CCS) project.

Science.gov (United States)

Li, Qi; Song, Ranran; Shi, Hui; Ma, Jianli; Liu, Xuehao; Li, Xiaochun

2018-04-01

The CO 2 injected into deep formations during implementation of carbon dioxide (CO 2 ) capture and storage (CCS) technology may leak and migrate into shallow aquifers or ground surfaces through a variety of pathways over a long period. The leaked CO 2 can threaten shallow environments as well as human health. Therefore, almost all monitoring programs for CCS projects around the world contain near-surface monitoring. This paper presents a U-tube based near-surface monitoring technology focusing on its first application in the Shenhua CCS demonstration project, located in the Ordos Basin, Inner Mongolia, China. First, background information on the site monitoring program of the Shenhua CCS demonstration project was provided. Then, the principle of fluid sampling and the monitoring methods were summarized for the U-tube sampler system, and the monitoring data were analyzed in detail. The U-tube based monitoring results showed that the U-tube sampler system is accurate, flexible, and representative of the subsurface fluid sampling process. The monitoring indicators for the subsurface water and soil gas at the Shenhua CCS site indicate good stratification characteristics. The concentration level of each monitoring indicator decreases with increasing depth. Finally, the significance of this near-surface environmental monitoring technology for CO 2 leakage assessments was preliminarily confirmed at the Shenhua CCS site. The application potential of the U-tube based monitoring technology was also demonstrated during the subsurface environmental monitoring of other CCS projects.

Experience of high-nitrogenous steel powder application in repairs and surface hardening of responsible parts for power equipment by plasma spraying

Science.gov (United States)

Kolpakov, A. S.; Kardonina, N. I.

2016-02-01

The questions of the application of novel diffusion-alloying high-nitrogenous steel powders for repair and surface hardening of responsible parts of power equipment by plasma spraying are considered. The appropriateness of the method for operative repair of equipment and increasing its service life is justified. General data on the structure, properties, and manufacture of nitrogen-, aluminum-, and chromium-containing steel powders that are economically alloyed using diffusion are described. It is noted that the nitrogen release during the decomposition of iron nitrides, when heating, protects the powder particles from oxidation in the plasma jet. It is shown that the coating retains 50% of nitrogen that is contained in the powder. Plasma spraying modes for diffusion-alloying high-nitrogenous steel powders are given. The service properties of plasma coatings based on these powders are analyzed. It is shown that the high-nitrogenous steel powders to a nitrogen content of 8.9 wt % provide the necessary wear resistance and hardness of the coating and the strength of its adhesion to the substrate and corrosion resistance to typical aggressive media. It is noted that increasing the coating porosity promotes stress relaxation and increases its thickness being limited with respect to delamination conditions in comparison with dense coatings on retention of the low defectiveness of the interface and high adhesion to the substrate. The examples of the application of high-nitrogenous steel powders in power engineering during equipment repairs by service companies and overhaul subdivisions of heat power plants are given. It is noted that the plasma spraying of diffusion-alloyed high-nitrogenous steel powders is a unique opportunity to restore nitrided steel products.

Potential utility of the thematic mapper for surface mine monitoring

International Nuclear Information System (INIS)

Irons, J.R.; Lachowski, H.M.

1981-01-01

One of many potential applications of the thematic mapper (TM) is surface mine monitoring. To assess this potential, data acquired by an aircraft multispectral scanner over Pennsylvania surface mines were preprocessed to simulate the anticipated spectral, spatial, and radiometric characteristics of TM data. False color imagery and thematic maps were derived from the simulated data and compared to imagery and maps derived from LANDSAT multispectral scanner subsystems data. On the basis of this comparison, TM data should definitely increase the detail and accuracy of remotely acquired surface mine information and may enable the remote determination of compliance with reclamation regulations

A strategy for Local Surface Stability Monitoring Using SAR Imagery

Science.gov (United States)

Kim, J.; Lan, C. W.; Lin, S. Y.; vanGasselt, S.; Yun, H.

2017-12-01

In order to provide sufficient facilities to satisfy a growing number of residents, nowadays there are many constructions and maintenance of infrastructures or buildings undergoing above and below the surface of urban area. In some cases we have learned that disasters might happen if the developments were conducted on unknown or geologically unstable ground or in over-developed areas. To avoid damages caused by such settings, it is essential to perform a regular monitoring scheme to understand the ground stability over the whole urban area. Through long-term monitoring, we firstly aim to observe surface stability over the construction sites. Secondly, we propose to implement an automatic extraction and tracking of suspicious unstable area. To achieve this, we used 12-days-interval C-band Sentinel-1A Synthetic Aperture Radar (SAR) images as the main source to perform regular monitoring. Differential Interferometric SAR (D-InSAR) technique was applied to generate interferograms. Together with the accumulation of updated Sentinel-1A SAR images, time series interferograms were formed accordingly. For the purpose of observing surface stability over known construction sites, the interferograms and the unwrapped products could be used to identify the surface displacement occurring before and after specific events. In addition, Small Baseline Subset (SBAS) and Permanent Scatterers (PS) approaches combining a set of unwrapped D-InSAR interferograms were also applied to derive displacement velocities over long-term periods. For some cases, we conducted the ascending and descending mode time series analysis to decompose three surface migration vectors and to precisely identify the risk pattern. Regarding the extraction of suspicious unstable areas, we propose to develop an automatic pattern recognition algorithm for the identification of specific fringe patterns involving various potential risks. The detected fringes were tracked in the time series interferograms and

Radiological monitoring plan for the Oak Ridge Y-12 Plant: Surface water

International Nuclear Information System (INIS)

1995-01-01

National Pollutant Discharge Elimination System (NPDES) Permit TN0002968, issued April 28, 1995, requires that the Y-12 Plant Radiological Monitoring Plan for surface water be modified (Part 111-H). These modifications shall consist of expanding the plan to include storm water monitoring and an assessment of alpha, beta, and gamma emitters. In addition, a meeting was held with personnel from the Tennessee Department of Environment and Conservation (TDEC) on May 4, 1995. In this meeting, TDEC personnel provided guidance to Y-12 Plant personnel in regard to the contents of the modified plan. This report contains a revised plan incorporating the permit requirements and guidance provided by TDEC personnel. In addition, modifications were made to address future requirements of the new regulation for radiation protection of the public and the environment in regards to surface water monitoring

Impact of climate change on surface ozone and deposition of sulphur and nitrogen in Europe

Energy Technology Data Exchange (ETDEWEB)

Langner, J.; Bergstroem, R.; Foltescu, V. [Swedish Meteorological and Hydrological Institute, Norrkoeping (Sweden)

2005-02-01

The potential impact of regional climate change on the distribution and deposition of air pollutants in Europe has been studied using a regional chemistry/transport/deposition model, MATCH. MATCH was set up using meteorological output from two 10-year climate change experiments made with the Rossby Centre regional Atmospheric climate model version 1 (RCA1). RCA1 was forced by boundary conditions from two different global climate models using the IPCC IS92a (business as usual) emission scenario. The global mean warming in both the GCMs was 2.6 K and was reached in the period 2050-2070. Simulations with MATCH indicate substantial potential impact of regional climate change on both deposition of oxidised nitrogen and concentrations of surface ozone. The simulations show a strong increase in surface ozone expressed as AOT40 and mean of daily maximum over southern and central Europe and a decrease in northern Europe. The simulated changes in April-September AOT40 are significant in relation to inter-annual variability over extended areas. Changes in deposition of oxidised nitrogen are much smaller and also less coherent due to the strong inter-annual variability in precipitation in the RCA1 simulations and differences in the regional climate change simulated with RCA1 in the two regional scenarios. Changes in simulated annual deposition are significant in relation to inter-annual variability only over small areas. This indicates that longer simulation periods are necessary to establish changes in deposition. (author)

Impact of climate change on surface ozone and deposition of sulphur and nitrogen in Europe

Science.gov (United States)

Langner, Joakim; Bergström, Robert; Foltescu, Valentin

The potential impact of regional climate change on the distribution and deposition of air pollutants in Europe has been studied using a regional chemistry/transport/deposition model, MATCH. MATCH was set up using meteorological output from two 10-year climate change experiments made with the Rossby Centre regional Atmospheric climate model version 1 (RCA1). RCA1 was forced by boundary conditions from two different global climate models using the IPCC IS92a (business as usual) emission scenario. The global mean warming in both the GCMs was 2.6 K and was reached in the period 2050-2070. Simulations with MATCH indicate substantial potential impact of regional climate change on both deposition of oxidised nitrogen and concentrations of surface ozone. The simulations show a strong increase in surface ozone expressed as AOT40 and mean of daily maximum over southern and central Europe and a decrease in northern Europe. The simulated changes in April-September AOT40 are significant in relation to inter-annual variability over extended areas. Changes in deposition of oxidised nitrogen are much smaller and also less coherent due to the strong inter-annual variability in precipitation in the RCA1 simulations and differences in the regional climate change simulated with RCA1 in the two regional scenarios. Changes in simulated annual deposition are significant in relation to inter-annual variability only over small areas. This indicates that longer simulation periods are necessary to establish changes in deposition.

Physical-chemical processes of astrophysical interest: nitrogen chemistry

International Nuclear Information System (INIS)

Loison, Jean-Christophe; Hickson, Kevin; Hily-Blant, Pierre; Faure, Alexandre; Vuitton, Veronique; Bacmann, A.; Maret, Sebastien; Legal, Romane; Rist, Claire; Roncero, Octavio; Larregaray, Pascal; Hochlaf, Majdi; Senent, M. L.; Capron, Michael; Biennier, Ludovic; Carles, Sophie; Bourgalais, Jeremy; Le Picard, Sebastien; Cordier, Daniel; Guillemin, Jean-Claude; Trolez, Yann; Bertin, M.; Poderoso, H.A.M.; Michaut, X.; Jeseck, P.; Philippe, L.; Fillion, J.H.; Fayolle, E.C.; Linnartz, H.; Romanzin, C.; Oeberg, K.I.; Roueff, Evelyne; Pagani, Laurent; Padovani, Marco; Wakelam, Veronique; Honvault, Beatrice; Zvereva-Loete, Natalia; Ouk, Chanda-Malis; Scribano, Yohann; Hartmann, J.M.; Pineau des Forets, Guillaume; Hernandez, Mario; Lique, Francois; Kalugina, Yulia N.; Stoecklin, T.; Hochlaf, M.; Crespos, C.; Larregaray, P.; Martin-Gondre, L.; Petuya, R.; Quintas Sanchez, E.L.; Zanchet, Alexandre; Rodriguez-Lazcano, Yamilet; Mate, Belen

2013-06-01

This document contains the programme and abstracts of contributions to a workshop on nitrogen chemistry within an astrophysical perspective. These contributions have been presented in sessions: Introduction (opening lecture, experimental approaches to molecular astrophysics, theoretical approaches to astrophysics, observations in molecular astrophysics), Physical-chemical theory of the gas phase (time-dependent approach in elementary activity, statistic approach in elementary activity in the case of the N+H_2 reaction, potential energy surfaces for inelastic and reactive collisions, collision rate for N_2H"+, ortho/para selection rules in the chemistry of nitrogen hydrides, cyanides/iso-cyanides excitation in the ISM, CN excitation, radiative association with N_2H as new interstellar anion, ro-vibratory excitation of HCN) Laboratory astrophysics (measurement of reaction products in the CRESUSOL project, reactivity of the CN- anion, N_2 photo-desorption in ices, CRESU study of nitrogen chemistry, chemistry of nitrogen complex molecules), Observations and chemistry of astrophysical media (the problem of interstellar nitrogen fractioning, abundance of N_2 in proto-stellar cores, HNC in Titan atmosphere and nitrogen-related mechanisms in hot Jupiters, HCN and HNC in dark clouds or how theoretical modelling helps in interpreting observations, nitrogen chemistry in cold clouds, deuteration of nitrogen hydrides, nitrogen in interstellar ices, biochemical molecules on Titan, coupling between excitation and chemistry, radiative transfer of nitrogen hydrides, ortho/para chemistry of nitrogen hydrides), Physical-chemical theory of gas-grain interactions (nitrogen reactivity on surfaces, IR spectra of ices of NH_3 and NH_3/N_2 mixtures)

Euthanasia of Small Animals with Nitrogen; Comparison with Intravenous Pentobarbital

OpenAIRE

Quine, John P.; Buckingham, William; Strunin, Leo

1988-01-01

Intravenous pentobarbital (with or without addition of saturated potassium chloride) was compared with nitrogen gas exposure for euthanasia of small animals (dogs, cats, and rabbits) in a humane society environment. Initially, electrocardiographic) and electroencephalographic monitoring were used to establish the time of death in presedated animals given either pentobarbital or exposed to nitrogen; later, nitrogen euthanasia alone was studied. Sedation with acepromazine delayed the effects of...

Groundwater Discharge of Legacy Nitrogen to River Networks: Linking Regional Groundwater Models to Streambed Groundwater-Surface Water Exchange and Nitrogen Processing

Science.gov (United States)

Barclay, J. R.; Helton, A. M.; Briggs, M. A.; Starn, J. J.; Hunt, A.

2017-12-01

Despite years of management, excess nitrogen (N) is a pervasive problem in many aquatic ecosystems. More than half of surface water in the United States is derived from groundwater, and widespread N contamination in aquifers from decades of watershed N inputs suggest legacy N discharging from groundwater may contribute to contemporary N pollution problems in surface waters. Legacy N loads to streams and rivers are controlled by both regional scale flow paths and fine-scale processes that drive N transformations, such as groundwater-surface water exchange across steep redox gradients that occur at stream bed interfaces. Adequately incorporating these disparate scales is a challenge, but it is essential to understanding legacy N transport and making informed management decisions. We developed a regional groundwater flow model for the Farmington River, a HUC-8 basin that drains to the Long Island Sound, a coastal estuary that suffers from elevated N loads despite decades of management, to understand broad patterns of regional transport. To evaluate and refine the regional model, we used thermal infrared imagery paired with vertical temperature profiling to estimate groundwater discharge at the streambed interface. We also analyzed discharging groundwater for multiple N species to quantify fine scale patterns of N loading and transformation via denitrification at the streambed interface. Integrating regional and local estimates of groundwater discharge of legacy N to river networks should improve our ability to predict spatiotemporal patterns of legacy N loading to and transformation within surface waters.

IMPROVING CYANOBACTERIA AND CYANOTOXIN MONITORING IN SURFACE WATERS FOR DRINKING WATER SUPPLY

Directory of Open Access Journals (Sweden)

Jing Li

2017-06-01

Full Text Available Cyanobacteria in fresh water can cause serious threats to drinking water supplies. Managing cyanobacterial blooms particularly at small drinking water treatment plants is challenging. Because large amount of cyanobacteria may cause clogging in the treatment process and various cyanotoxins are hard to remove, while they may cause severe health problems. There is lack of instructions of what cyanobacteria/toxin amount should trigger what kind of actions for drinking water management except for Microcystins. This demands a Cyanobacteria Management Tool (CMT to help regulators/operators to improve cyanobacteria/cyanotoxin monitoring in surface waters for drinking water supply. This project proposes a CMT tool, including selecting proper indicators for quick cyanobacteria monitoring and verifying quick analysis methods for cyanobacteria and cyanotoxin. This tool is suggested for raw water management regarding cyanobacteria monitoring in lakes, especially in boreal forest climate. In addition, it applies to regions that apply international WHO standards for water management. In Swedish context, drinking water producers which use raw water from lakes that experience cyanobacterial blooms, need to create a monitoring routine for cyanobacteria/cyanotoxin and to monitor beyond such as Anatoxins, Cylindrospermopsins and Saxitoxins. Using the proposed CMT tool will increase water safety at surface water treatment plants substantially by introducing three alerting points for actions. CMT design for each local condition should integrate adaptive monitoring program.

Monitoring surface water quality using social media in the context of citizen science

Science.gov (United States)

Zheng, Hang; Hong, Yang; Long, Di; Jing, Hua

2017-02-01

Surface water quality monitoring (SWQM) provides essential information for water environmental protection. However, SWQM is costly and limited in terms of equipment and sites. The global popularity of social media and intelligent mobile devices with GPS and photography functions allows citizens to monitor surface water quality. This study aims to propose a method for SWQM using social media platforms. Specifically, a WeChat-based application platform is built to collect water quality reports from volunteers, which have been proven valuable for water quality monitoring. The methods for data screening and volunteer recruitment are discussed based on the collected reports. The proposed methods provide a framework for collecting water quality data from citizens and offer a primary foundation for big data analysis in future research.

Nitrogen retention in river corridors: European perspective

Energy Technology Data Exchange (ETDEWEB)

Haycock, N [Dept. of Agriculture and Water Management, Silsoe College, Cranfield Institute of Technology (United Kingdom); Pinay, G [CERR/CNRS, Toulouse (France); Walker, Charles [SBEG, Inst. of Ecology, Lund Univ. (Sweden)

1993-01-01

The problem of nitrogen pollution in European surface- and groundwaters has become a focus of recent European and Scandinavian directives, with legislation calling for a 50% reduction of N losses by the years 1995 and 2000, respectively. This paper provides a conceptual framework upon which management strategies to reduce losses of diffuse nitrogen pollution to surface waters may be based. The control of nitrogen pollution may take place through an increase in the complexity of the landscape, not throughout the catchment area, but rather in specific zones, the river corridor in particular. Within river corridors, riparian areas have been recognized globally for their value as nutrient removal ''buffer systems''. Studies have identified vegetation uptake and microbial denitrification as the primary mechanisms responsible for N removal in these systems. For these processes to function optimally on an annual basis, both vegetation and water regime must be managed. The establishment and management of riparian buffer zones in suitable places within river corridors, will provide a stable and sustainable water-protection function. This will complement future nitrogen input control strategies, needed for both the long-term protection of groundwater and surface waters in Europe as a whole, and for the proposed 50% reduction in nitrogen loading to the Baltic and North Sea coastal waters by the turn of the century. 52 refs, 5 figs

Simulation of water vapor condensation on LOX droplet surface using liquid nitrogen

Science.gov (United States)

Powell, Eugene A.

1988-01-01

The formation of ice or water layers on liquid oxygen (LOX) droplets in the Space Shuttle Main Engine (SSME) environment was investigated. Formulation of such ice/water layers is indicated by phase-equilibrium considerations under conditions of high partial pressure of water vapor (steam) and low LOX droplet temperature prevailing in the SSME preburner or main chamber. An experimental investigation was begun using liquid nitrogen as a LOX simulant. A monodisperse liquid nitrogen droplet generator was developed which uses an acoustic driver to force the stream of liquid emerging from a capillary tube to break up into a stream of regularly space uniformly sized spherical droplets. The atmospheric pressure liquid nitrogen in the droplet generator reservoir was cooled below its boiling point to prevent two phase flow from occurring in the capillary tube. An existing steam chamber was modified for injection of liquid nitrogen droplets into atmospheric pressure superheated steam. The droplets were imaged using a stroboscopic video system and a laser shadowgraphy system. Several tests were conducted in which liquid nitrogen droplets were injected into the steam chamber. Under conditions of periodic droplet formation, images of 600 micron diameter liquid nitrogen droplets were obtained with the stroboscopic video systems.

Monitoring of Water and Contaminant Migration at the Groundwater-Surface Water Interface

Science.gov (United States)

2008-08-01

seepage is occurring in a freshwater lake environment and to map the lateral extent of any subsurface contamination at the groundwater –surface water ...and Contaminant Migration at the Groundwater -Surface Water Interface August 2008 Report Documentation Page Form ApprovedOMB No. 0704-0188 Public...4. TITLE AND SUBTITLE Monitoring of Water and Contaminant Migration at the Groundwater -Surface Water Interface 5a. CONTRACT NUMBER 5b. GRANT NUMBER

Effect of Low-Pressure Nitrogen DC Plasma Treatment on the Surface Properties of Biaxially Oriented Polypropylene, Poly (Methyl Methacrylate) and Polyvinyl Chloride Films

International Nuclear Information System (INIS)

Mortazavi, S. Hamideh; Ghoranneviss, Mahmood; Pilehvar, Soheil; Esmaeili, Sina; Zargham, Shamim; Hashemi, S. Ebrahim; Jodat, Hamzeh

2013-01-01

In this study, commercial biaxially oriented polypropylene (BOPP), polyvinyl chloride (PVC) and poly (methyl methacrylate) (PMMA) films were treated with nitrogen plasma over different exposure times in a Pyrex tube surrounded by a DC variable magnetic field. The chemical changes that appeared on the surface of the samples were investigated using Fourier transform infrared (FT-IR) spectroscopy and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy after treatment for 2 min, 4 min and 6 min in a nitrogen plasma chamber. Effects of the plasma treatment on the surface topographies and contact angles of the untreated and plasma treated films were also analyzed by atomic force microscopy (AFM) and a contact angle measuring system. The results show that the plasma treated films become more hydrophilic with an enhanced wettability due to the formation of some new polar groups on the surface of the treated films. Moreover, at higher exposure times, the total surface energy in all treated films increased while a reduction in contact angle occurred. The behavior of surface roughness in each sample was completely different at higher exposure times. (plasma technology)

A statistical correlation investigation for the role of surface spins to the spin relaxation of nitrogen vacancy centers

Energy Technology Data Exchange (ETDEWEB)

Song, Xuerui; Zhang, Jian; Feng, Fupan; Wang, Junfeng; Zhang, Wenlong; Lou, Liren; Zhu, Wei; Wang, Guanzhong, E-mail: gzwang@ustc.edu.cn [Hefei National Laboratory for Physical Science at Microscale, and Department of Physics, University of Science and Technology of China, Hefei, Anhui, 230026 (China)

2014-04-15

We investigated the influence of spins on surface of nanodiamonds (NDs) to the longitudinal relaxation time (T{sub 1}) and transverse relaxation time (T{sub 2}) of nitrogen vacancy (NV) centers in ND. A spherical model of the NDs was suggested to account for the experimental results of T{sub 1} and T{sub 2}, and the density of surface spins was roughly estimated based on the statistical analysis of experimental results of 72 NDs containing a single NV center. For NDs studied here, the T{sub 1} of NV center inside is highly dependent to the surface spins of the NDs. However, for the T{sub 2} of NV center, intrinsic contributions must be much pronounced than that by surface spins. In other words, T{sub 1} of an NV center in NDs is more sensitive to the change of the surface spin density than T{sub 2}.

A statistical correlation investigation for the role of surface spins to the spin relaxation of nitrogen vacancy centers

Directory of Open Access Journals (Sweden)

Xuerui Song

2014-04-01

Full Text Available We investigated the influence of spins on surface of nanodiamonds (NDs to the longitudinal relaxation time (T1 and transverse relaxation time (T2 of nitrogen vacancy (NV centers in ND. A spherical model of the NDs was suggested to account for the experimental results of T1 and T2, and the density of surface spins was roughly estimated based on the statistical analysis of experimental results of 72 NDs containing a single NV center. For NDs studied here, the T1 of NV center inside is highly dependent to the surface spins of the NDs. However, for the T2 of NV center, intrinsic contributions must be much pronounced than that by surface spins. In other words, T1 of an NV center in NDs is more sensitive to the change of the surface spin density than T2.

Improvement of a device for monitoring the contamination of surfaces

International Nuclear Information System (INIS)

Barbier, Albert.

1981-01-01

The purpose of this invention is to make it possible to monitor the contamination of surfaces by a light weight portable device and enabling the alpha, beta and gamma radiation contamination to be detected. The detection probe which is connected by a single lead to the box is adapted, in each particular case, to the radiation mode emitted by the contaminated surfaces and the box is provided with a special leak-proof socket for connecting the probe and includes means for assessing the counting rate of the radiation given off, depending on the mode of the radiations emitted by the contaminated surfaces and the intensity of the count rate [fr

Carbon and nitrogen accumulation in forest floor and surface soil under different geographic origins of Maritime pine (Pinus pinaster Aiton.) plantations

Energy Technology Data Exchange (ETDEWEB)

Ozdemir, E.; Oral, H. V.; Akburak, S.; Makineci, E.; Yilmaz, E.

2013-09-01

Aim of study: To determine if plantations consisting of different geographic origins of the Maritime pine (Pinus pinaster Aiton.) could have altered C and N stocks in the forest floor and surface soils. Area of study: Forest floor and mineral soil C and N stocks were measured in four adjacent plantations of different geographic origins of Maritime pine (Gironde, Toulon, Corsica and Spain) and adjacent primary native Sessile oak (Quercus petraea L.) at Burunsuz region in Belgrad Forest where is located in the Istanbul province in the Marmara geographical region between 41° 09’-41° 12’ N latitude and 28° 54’-29° 00’ E longitude in Turkey. Material and methods: Plots were compared as common garden experiments without replications. 15 surface soil (0-10 cm) and 15 forest floor samples were taken from each Maritime pine origins and adjacent native Sessile oak forest. C and N contents were determined on LECO Truspec 2000 CN analyzer. The statistical significance of the results was evaluated by one-way Analysis of Variance (ANOVA). Research highlights: Forest floor carbon mass, nitrogen concentration and nitrogen mass of forest floor showed a significant difference among origins. Soil carbon mass and nitrogen mass did not significantly differ among investigated plots. (Author)

Effect of surface modification by nitrogen ion implantation on the electrochemical and cellular behaviors of super-elastic NiTi shape memory alloy.

Science.gov (United States)

Maleki-Ghaleh, H; Khalil-Allafi, J; Sadeghpour-Motlagh, M; Shakeri, M S; Masoudfar, S; Farrokhi, A; Beygi Khosrowshahi, Y; Nadernezhad, A; Siadati, M H; Javidi, M; Shakiba, M; Aghaie, E

2014-12-01

The aim of this investigation was to enhance the biological behavior of NiTi shape memory alloy while preserving its super-elastic behavior in order to facilitate its compatibility for application in human body. The surfaces of NiTi samples were bombarded by three different nitrogen doses. Small-angle X-ray diffraction was employed for evaluating the generated phases on the bombarded surfaces. The electrochemical behaviors of the bare and surface-modified NiTi samples were studied in simulated body fluid (SBF) using electrochemical impedance and potentio-dynamic polarization tests. Ni ion release during a 2-month period of service in the SBF environment was evaluated using atomic absorption spectrometry. The cellular behavior of nitrogen-modified samples was studied using fibroblast cells. Furthermore, the effect of surface modification on super-elasticity was investigated by tensile test. The results showed the improvement of both corrosion and biological behaviors of the modified NiTi samples. However, no significant change in the super-elasticity was observed. Samples modified at 1.4E18 ion cm(-2) showed the highest corrosion resistance and the lowest Ni ion release.

A Laboratory Experimental Study: An FBG-PVC Tube Integrated Device for Monitoring the Slip Surface of Landslides

Science.gov (United States)

Zhang, Shaojie; Chen, Jiang; Teng, Pengxiao; Wei, Fangqiang; Chen, Qiao

2017-01-01

A new detection device was designed by integrating fiber Bragg grating (FBG) and polyvinyl chloride (PVC) tube in order to monitor the slip surface of a landslide. Using this new FBG-based device, a corresponding slope model with a pre-set slip surface was designed, and seven tests with different soil properties were carried out in laboratory conditions. The FBG sensing fibers were fixed on the PVC tube to measure strain distributions of PVC tube at different elevation. Test results indicated that the PVC tube could keep deformation compatible with soil mass. The new device was able to monitor slip surface location before sliding occurrence, and the location of monitored slip surface was about 1–2 cm above the pre-set slip surface, which basically agreed with presupposition results. The monitoring results are expected to be used to pre-estimate landslide volume and provide a beneficial option for evaluating the potential impact of landslides on shipping safety in the Three Gorges area. PMID:29084157

The determination of surface of powders by BET method using nitrogen and krypton with computer calculation of the results

International Nuclear Information System (INIS)

Dembinski, W.; Zlotowski, T.

1973-01-01

A computer program written in FORTRAN language for calculations of final results of specific surface analysis based on BET theory has been described. Two gases - nitrogen and krypton were used. A technical description of measuring apparaturs is presented as well as theoretical basis of the calculations together with statistical analysis of the results for uranium compounds powders. (author)

Using Stable Isotopes to Detect Land Use Change and Nitrogen Sources in Aquatic Systems

Energy Technology Data Exchange (ETDEWEB)

Rogers, K. M. [National Isotope Center, GNS Science, Lower Hutt (New Zealand)

2013-05-15

Changing land use is one of the primary causes of increased sedimentation and nutrient levels in aquatic systems, resulting in contamination and reduction of biodiversity. Detecting and quantifying these inputs is the first step towards remediation, and enabling targeted reductions of transport processes into waterways from human impacted land surfaces. More recently, stable isotope analyses are being used as detection and quantification tools in aquatic environments. Carbon ({delta}{sup 13}C) and nitrogen ({delta}{sup 15}N) isotopes of sediments, as well as algae and invertebrates from aquatic systems can be used as proxies to record both short and long term environmental change. Excess nitrogen (or nitrogen-compounds) derived from urbanization, industry, forestry, farming and agriculture, increase the bioavailability of nitrogen to aquatic organisms, changing their natural {delta}15N isotopic signatures. Allochthonous (terrestrial) input from soil destabilization and human activity in surrounding catchments changes {delta}{sup 13}C isotopic compositions and increases the C:N ratio of sediments. Heavy metal and other organic pollutants can also be used to indicate urbanization and industrial contamination. The combined use of carbon and nitrogen isotopes, C:N ratios and heavy metals are powerful environmental monitoring tools, which are useful indicators of source and transport pathways of terrestrial derived material and anthropogenic pollutants into streams, rivers and estuaries. (author)

Remote sensing techniques to monitor nitrogen-driven carbon dynamics in field corn

Science.gov (United States)

Corp, Lawrence A.; Middleton, Elizabeth M.; Campbell, Petya K. E.; Huemmrich, K. Fred; Cheng, Yen-Ben; Daughtry, Craig S. T.

2009-08-01

Patterns of change in vegetation growth and condition are one of the primary indicators of the present and future ecological status of the globe. Nitrogen (N) is involved in photochemical processes and is one of the primary resources regulating plant growth. As a result, biological carbon (C) sequestration is driven by N availability. Large scale monitoring of photosynthetic processes are currently possible only with remote sensing systems that rely heavily on passive reflectance (R) information. Unlike R, fluorescence (F) emitted from chlorophyll is directly related to photochemical reactions and has been extensively used for the elucidation of the photosynthetic pathways. Recent advances in passive fluorescence instrumentation have made the remote acquisition of solar-induced fluorescence possible. The goal of this effort is to evaluate existing reflectance and emerging fluorescence methodologies for determining vegetation parameters related to photosynthetic function and carbon sequestration dynamics in plants. Field corn N treatment levels of 280, 140, 70, and 0 kg N / ha were sampled from an intensive test site for a multi-disciplinary project, Optimizing Production Inputs for Economic and Environmental Enhancement (OPE). Aircraft, near-ground, and leaf-level measurements were used to compare and contrast treatment effects within this experiment site assessed with both reflectance and fluorescence approaches. A number of spectral indices including the R derivative index D730/D705, the normalized difference of R750 vs. R705, and simple ratio R800/R750 differentiated three of the four N fertilization rates and yielded high correlations to three important carbon parameters: C:N, light use efficiency, and grain yield. These results advocate the application of hyperspectral sensors for remotely monitoring carbon cycle dynamics in terrestrial ecosystems.

Nitrogen implantation into silicon at 700-1100 deg C

International Nuclear Information System (INIS)

Kachurin, G.A.; Tyschenko, I.E.; Popov, V.P.; Tijs, S.A.; Plotnikov, A.E.

1989-01-01

Nitrogen ions 130-140 kW potential accelerated were implanted in silicon heated up to Ti=700-1100 deg C. Densities of ion current were 1-5 mcA/cm 2 , doses did not exceed 5x10 17 cm -2 . Initial stages of nitride formation in buried layers are investigated by means of Rutherford backscattering, layer-by-layer Augerspctroscopy and electron microscopy. It is determind, that Ti growth from 700 up to 900 deg C is accompanied by essential reduction of defectiveness of silicon near-the-surface layer at nitrogen retention within the limits of the calculation profile of ion ranges. At Ti=900 deg C nitrogen is rather mobile and at ∼5x10 16 cm -2 dose it is drown to α-Si 3 N 4 crystalling extraction in R p range. Beginning from Ti ≅1000 deg C nitrogen is not retained in the furied layer and diffuses to the surface. No essenstial losses of nitrogen due to evaporation or inside diffusion are observed. It is noted, that critical Ti, when nitrogen is accumulated in the buried layer, correspond to critical temperatures, when light ions introduce essential structure distortions. Conclusion is made, that irradition-introduced distortions of structure represent centres of initiation and growth of nitride phase. At 1150 deg C additional annaling during 3 hs nitrogen, occurring outside the stable extraction, is redistributed between th surface and furied layers, sintering in narrow concentration peaks

Click chemistry based biomolecular conjugation monitoring using surface-enhanced Raman spectroscopy mapping

DEFF Research Database (Denmark)

Palla, Mirko; Kumar, Shiv; Li, Zengmin

2016-01-01

We describe here a novel surface-enhanced Raman spectroscopy (SERS) based technique for monitoring the conjugation of small molecules by the well-known click reaction between an alkyne and azido moiety on the partner molecules. The monitoring principle is based on the loss of the characteristic...... alkyne/azide Raman signal with triazole formation in the reaction as a function of time. Since these universal Raman reporter groups are specific for click reactions, this method may facilitate a broad range of applications for monitoring the conjugation efficiency of molecules in diverse areas...

Modeling and Simulated Annealing Optimization of Surface Roughness in CO2 Laser Nitrogen Cutting of Stainless Steel

Directory of Open Access Journals (Sweden)

M. Madić

2013-09-01

Full Text Available This paper presents a systematic methodology for empirical modeling and optimization of surface roughness in nitrogen, CO2 laser cutting of stainless steel . The surface roughness prediction model was developed in terms of laser power , cutting speed , assist gas pressure and focus position by using The artificial neural network ( ANN . To cover a wider range of laser cutting parameters and obtain an experimental database for the ANN model development, Taguchi 's L27 orthogonal array was implemented in the experimental plan. The developed ANN model was expressed as an explicit nonlinear function , while the influence of laser cutting parameters and their interactions on surface roughness were analyzed by generating 2D and 3D plots . The final goal of the experimental study Focuses on the determinationof the optimum laser cutting parameters for the minimization of surface roughness . Since the solution space of the developed ANN model is complex, and the possibility of many local solutions is great, simulated annealing (SA was selected as a method for the optimization of surface roughness.

The microstructure and surface hardness of Ti6Al4V alloy implanted with nitrogen ions at an elevated temperature

Energy Technology Data Exchange (ETDEWEB)

Vlcak, Petr, E-mail: petr.vlcak@fs.cvut.cz [Department of Physics, Faculty of Mechanical Engineering, Czech Technical University in Prague, Technicka 4, 16607 Prague (Czech Republic); Cerny, Frantisek [Department of Physics, Faculty of Mechanical Engineering, Czech Technical University in Prague, Technicka 4, 16607 Prague (Czech Republic); Drahokoupil, Jan [Department of Metals, Institute of Physics, AS CR, v.v.i., Na Slovance 2, 182 21 Prague (Czech Republic); Sepitka, Josef [Department of Mechanics, Biomechanics and Mechatronics, Faculty of Mechanical Engineering, Czech Technical University in Prague, Technicka 4, 16607 Prague (Czech Republic); Tolde, Zdenek [Department of Materials Engineering, Faculty of Mechanical Engineering, Czech Technical University in Prague, Technicka 4, 16607 Prague (Czech Republic)

2015-01-25

Highlights: • The Ti6Al4V samples were implanted with 90 keV nitrogen ions. • The samples were annealed at 500 °C during the ion implantation process. • An elevated temperature increases the mobility of the atoms and the quantity of TiN. • The hardness showed a significant increase compared to room temperature implantation. - Abstract: The effect of an elevated temperature during nitrogen ion implantation on the microstructure and on the surface hardness of Ti6Al4V titanium alloy was examined. The implantation process was carried out at fluences of 1 ⋅ 10{sup 17}, 2.7 ⋅ 10{sup 17} and 6 ⋅ 10{sup 17} cm{sup −2} and at ion energy 90 keV. The implanted samples were annealed at 500 °C during the implantation process. X-ray diffraction analysis was performed to obtain a phase characterization and a phase quantification in the implanted sample surface. The surface hardness was investigated by nanoindentation testing, and the nitrogen depth distribution was measured by Rutherford Backscattering Spectroscopy. Elevated temperature led to increased formation of a TiN compound. It was found that a mixture of TiN and an α-Ti(+N) solid solution had a predominant amount of TiN for samples with fluence of 2.7 ⋅ 10{sup 17} cm{sup −2} or higher. Elevated temperature during ion implantation caused an increase in surface hardening more towards the depth of the substrate in comparison with room temperature implantation. The hardness showed a remarkably significant increase at a fluence of 1 ⋅ 10{sup 17} and 2.7 ⋅ 10{sup 17} cm{sup −2} compared to samples implanted at the same fluences and at room temperature. There is a discussion of such mechanisms that explain the observed hardening more towards the depth of the substrate, and the increase in hardness.

[Runoff loss of soil mineral nitrogen and its relationship with grass coverage on Loess slope land].

Science.gov (United States)

Zhang, Yali; Li, Huai'en; Zhang, Xingchang; Xiao, Bo

2006-12-01

In a simulated rainfall experiment on Loess slope land, this paper determined the rainfall, surface runoff and the effective depth of interaction (EDI) between rainfall and soil mineral nitrogen, and studied the effects of grass coverage on the EDI and the runoff loss of soil mineral nitrogen. The results showed that with the increase of EDI, soil nitrogen in deeper layers could be released into surface runoff through dissolution and desorption. The higher the grass coverage, the deeper the EDI was. Grass coverage promoted the interaction between surface runoff and surface soil. On the slope land with 60%, 80% and 100% of grass coverage, the mean content of runoff mineral nitrogen increased by 34.52%, 32.67% and 6.00%, while surface runoff decreased by 4.72%, 9.84% and 12.89%, and eroded sediment decreased by 83.55%, 87.11% and 89.01%, respectively, compared with bare slope land. The total runoff loss of soil mineral nitrogen on the lands with 60%, 80%, and 100% of grass coverage was 95.73%, 109.04%, and 84.05% of that on bare land, respectively. Grass cover had dual effects on the surface runoff of soil mineral nitrogen. On one hand, it enhanced the influx of soil mineral nitrogen to surface runoff, and on the other hand, it markedly decreased the runoff, resulting in the decrease of soil mineral nitrogen loss through runoff and sediment. These two distinct factors codetermined the total runoff loss of soil mineral nitrogen.

Nitrogen plasma immersion ion implantation for surface treatment and wear protection of austenitic stainless steel X6CrNiTi1810

International Nuclear Information System (INIS)

Blawert, C.; Mordike, B.L.

1999-01-01

Plasma immersion ion implantation is an effective surface treatment for stainless steels. The influence of treatment parameters (temperature, plasma density and pressure) on the sliding wear resistance are studied here. At moderate temperatures, nitrogen remains in solid solution without forming nitrides. This increases the surface hardness and the wear resistance without affecting the passivation of the steel. This may allow the use of such steels in applications where their poor wear resistance would normally prohibit their use. (orig.)

Assessment of radiation emitted by the colour video monitors using a silicon surface-barrier detection system

International Nuclear Information System (INIS)

Tykva, R.; Sabol, J.

1998-01-01

About 5% of the commonly used colour monitors tested showed radiation levels on the screen surface approaching the dose rate of 5 μGy/h. There is practically no difference between 'low radiation' monitors and other monitors. The level of radiation emitted to the sides is generally higher than that of X-ray photons emerging from the surface of the screen. Although the contribution to the effective dose of a person exposed to radiation from the monitors may be below the limit set for the general public, the skin and eye lens dose may reach significant levels, taking into account some factors such as a high density of monitors in small rooms, short distance, long exposure time, etc. (M.D.)

Trends in Surface-Water Quality at Selected Ambient-Monitoring Network Stations in Kentucky, 1979-2004

Science.gov (United States)

Crain, Angela S.; Martin, Gary R.

2009-01-01

Increasingly complex water-management decisions require water-quality monitoring programs that provide data for multiple purposes, including trend analyses, to detect improvement or deterioration in water quality with time. Understanding surface-water-quality trends assists resource managers in identifying emerging water-quality concerns, planning remediation efforts, and evaluating the effectiveness of the remediation. This report presents the results of a study conducted by the U.S. Geological Survey, in cooperation with the Kentucky Energy and Environment Cabinet-Kentucky Division of Water, to analyze and summarize long-term water-quality trends of selected properties and water-quality constituents in selected streams in Kentucky's ambient stream water-quality monitoring network. Trends in surface-water quality for 15 properties and water-quality constituents were analyzed at 37 stations with drainage basins ranging in size from 62 to 6,431 square miles. Analyses of selected physical properties (temperature, specific conductance, pH, dissolved oxygen, hardness, and suspended solids), for major ions (chloride and sulfate), for selected metals (iron and manganese), for nutrients (total phosphorus, total nitrogen, total Kjeldahl nitrogen, nitrite plus nitrate), and for fecal coliform were compiled from the Commonwealth's ambient water-quality monitoring network. Trend analyses were completed using the S-Plus statistical software program S-Estimate Trend (S-ESTREND), which detects trends in water-quality data. The trend-detection techniques supplied by this software include the Seasonal Kendall nonparametric methods for use with uncensored data or data censored with only one reporting limit and the Tobit-regression parametric method for use with data censored with multiple reporting limits. One of these tests was selected for each property and water-quality constituent and applied to all station records so that results of the trend procedure could be compared among

Computing wheat nitrogen requirements from grain yield and protein maps

Science.gov (United States)

Optical protein sensors and mass-flow yield monitors provide the opportunity to continuously measure grain quality and quantity during harvesting. This chapter illustrates how yield monitor and grain protein measurements may provide useful postharvest information for evaluating water or nitrogen (N)...

Monitoring Multidecadal satellite earth observation of soil moisture products through land surface reanalysis

NARCIS (Netherlands)

Albergel, C.; Dorigo, W.; Balsamo, G.; Sabatar, J; de Rosnay, P.; Isaksen, I; Brocca, L; de Jeu, R.A.M.; Wagner, W.

2013-01-01

Soil moisture from ERA-Land, a revised version of the land surface components of the European Centre for Medium-Range Weather Forecasts Interim reanalysis (ERA-Interim), is used to monitor at a global scale the consistency of a new microwave based multi-satellite surface soil moisture date set

Carbon and nitrogen accumulation in forest floor and surface soil under different geographic origins of Maritime pine (Pinus pinaster Aiton. plantations

Directory of Open Access Journals (Sweden)

E. Ozdemir

2013-07-01

Full Text Available Aim of study : To determine if plantations consisting of different geographic origins of the Maritime pine (Pinus pinaster Aiton. could have altered C and N stocks in the forest floor and surface soils.Area of study : Forest floor and mineral soil C and N stocks were measured in four adjacent plantations of different geographic origins of Maritime pine (Gironde, Toulon, Corsica and Spain and adjacent primary native Sessile oak (Quercus petraea L. at Burunsuz region in Belgrad Forest where is located in the Istanbul province in the Marmara geographical region between 41°09' -41°12' N latitude and 28°54' - 29°00' E longitude in Turkey.Material and Methods : Plots were compared as common garden experiments without replications. 15 surface soil (0-10 cm and 15 forest floor samples were taken from each Maritime pine origins and adjacent native Sessile oak forest. C and N contents were determined on LECO Truspec 2000 CN analyzer. The statistical significance of the results was evaluated by one-way Analysis of Variance (ANOVA.Research highlights : Forest floor carbon mass, nitrogen concentration and nitrogen mass of forest floor showed a significant difference among origins. Soil carbon mass and nitrogen mass did not significantly differ among investigated plots.Keywords: carbon sequestration; C/N ratio; decomposition; exotic; tree provenance.

Nitrogen concentration profiles in oxy-nitrited high-speed steel

International Nuclear Information System (INIS)

Barcz, A.; Turos, A.; Wielunski, L.

1976-01-01

Nuclear microanalysis has been applied for the determination of in-depth concentration profiles of nitrogen in oxy-nitrided high-speed steel. The concentration profiles were deduced from measurements of the nitrogen content, determined by means of the 14 N(d,α) 12 C reaction for the set of initially identical samples after the removal of surface layers of sequentially increasing thicknesses. The 1.2 MeV deuterons were obtained from the Institute of Nuclear Research Van de Graaf accelerator LECH. The α-particles produced in the 14 N(d,α) 12 C reaction were detected by means of silicon surface barrier detector mounted at 150 deg C. Strong blocking of the nitrogen diffusion due to the presence of oxygen has been observed. The accuracy of nitrogen detection is of the order of 5% for nitrogen-rich regions and 10% for the matrix. However, the local non-uniformity of the steel may cause a spread of about 20% of the measured values. (T.G.)

Toxicity research of boron-nitrogen modifiers of wooden surface

Directory of Open Access Journals (Sweden)

Klyachenkova Ol'ga Aleksandrovna

2014-07-01

Full Text Available Boron-nitrogen compounds (BNC have been successfully used to create bio- and fire-protective compositions for wood. Within the framework of this study, our aim was to assess the toxicity of the boron-nitrogen compounds by bioluminescent method with the use of environmental control device "Biotox-10M" and highly sensitive biosensor "Ecolum". We also defined toxicological parameters EC20 and EC50 and concluded, that all the wood preservation compounds are highly toxic, whereby, it is advisable to use them for external protection of wooden structures. As a result of BNC toxicity assessment, it is necessary to consider that any effective bio- and fireprotectives, will be highly toxic. Our researches stated, that BNC protective compositions are highly toxic and, therefore, it is possible to conclude their applicability for external wood processing.

A one-step carbonization route towards nitrogen-doped porous carbon hollow spheres with ultrahigh nitrogen content for CO 2 adsorption

KAUST Repository

Wang, Yu

2015-01-01

© The Royal Society of Chemistry 2015. Nitrogen doped porous carbon hollow spheres (N-PCHSs) with an ultrahigh nitrogen content of 15.9 wt% and a high surface area of 775 m² g^-1 were prepared using Melamine-formaldehyde nanospheres as hard templates and nitrogen sources. The N-PCHSs were completely characterized and were found to exhibit considerable CO2 adsorption performance (4.42 mmol g^-1).

Growth of 1.5 micron gallium indium nitrogen arsenic antimonide vertical cavity surface emitting lasers by molecular beam epitaxy

Science.gov (United States)

Wistey, Mark Allan

Fiber optics has revolutionized long distance communication and long haul networks, allowing unimaginable data speeds and noise-free telephone calls around the world for mere pennies per hour at the trunk level. But the high speeds of optical fiber generally do not extend to individual workstations or to the home, in large part because it has been difficult and expensive to produce lasers which emitted light at wavelengths which could take advantage of optical fiber. One of the most promising solutions to this problem is the development of a new class of semiconductors known as dilute nitrides. Dilute nitrides such as GaInNAs can be grown directly on gallium arsenide, which allows well-established processing techniques. More important, gallium arsenide allows the growth of vertical-cavity surface-emitting lasers (VCSELs), which can be grown in dense, 2D arrays on each wafer, providing tremendous economies of scale for manufacturing, testing, and packaging. Unfortunately, GaInNAs lasers have suffered from what has been dubbed the "nitrogen penalty," with high thresholds and low efficiency as the fraction of nitrogen in the semiconductor was increased. This thesis describes the steps taken to identify and essentially eliminate the nitrogen penalty. Protecting the wafer surface from plasma ignition, using an arsenic cap, greatly improved material quality. Using a Langmuir probe, we further found that the nitrogen plasma source produced a large number of ions which damaged the wafer during growth. The ions were dramatically reduced using deflection plates. Low voltage deflection plates were found to be preferable to high voltages, and simulations showed low voltages to be adequate for ion removal. The long wavelengths from dilute nitrides can be partly explained by wafer damage during growth. As a result of these studies, we demonstrated the first CW, room temperature lasers at wavelengths beyond 1.5mum on gallium arsenide, and the first GaInNAs(Sb) VCSELs beyond 1

Ruminal Nitrogen Recycling and Nitrogen Efficiency in Lactating Dairy Cattle

OpenAIRE

Aguilar, Michelle

2012-01-01

Excess nitrogen (N) excretion from animal agriculture results in reduced air and water quality, and poses a risk to human health. Although the dairy industry utilizes milk urea N (MUN) to monitor protein feeding and N excretion, phenotypic diversity among cows may influence MUN and thus bias feed management. An initial study using data from 2 previously published research trials and a field trial, observed that cow had a significant effect on MUN variation. Regression models, utilized ...

Isotope investigation of nitrogen in the hydrosphere

International Nuclear Information System (INIS)

Heaton, T.H.E.

1985-01-01

Compounds of nitrogen are essential, often limiting nutrients, and the nitrogen cycle is therefore one of the most important of the earth's major elements cycles. Of all the cycles, however, the nitrogen cycle is also probably the one most influenced by human activity. This activity has resulted in the increase in reactive nitrogen compounds to such an extent that they now present major forms of pollution. Any strategies aimed at counteracting these disturbances require a better understanding of the sources and reaction processes for nitrogen compounds, and studies of natural variations in 15 N/ 14 N ratio are now being used for this purpose in all parts of the hydrosphere. This paper reviews the isotopic method for tracing sources of nitrate in ground and surface waters

DETERMINATION OF HEAT TRANSFER COEFFICIENTS FOR FRENCH PLASTIC SEMEN STRAW SUSPENDED IN STATIC NITROGEN VAPOR OVER LIQUID NITROGEN.

Science.gov (United States)

Santo, M V; Sansinena, M; Chirife, J; Zaritzky, N

2015-01-01

The use of mathematical models describing heat transfer during the freezing process is useful for the improvement of cryopreservation protocols. A widespread practice for cryopreservation of spermatozoa of domestic animal species consists of suspending plastic straws in nitrogen vapor before plunging into liquid nitrogen. Knowledge of surface heat transfer coefficient (h) is mandatory for computational modelling; however, h values for nitrogen vapor are not available. In the present study, surface heat transfer coefficients for plastic French straws immersed in nitrogen vapor over liquid nitrogen was determined; vertical and horizontal positions were considered. Heat transfer coefficients were determined from the measurement of time-temperature curves and from numerical solution of heat transfer partial differential equation under transient conditions using finite elements. The h values experimentally obtained for horizontal and vertically placed straws were compared to those calculated using correlations based on the Nusselt number for natural convection. For horizontal straws the average obtained value was h=12.5 ± 1.2 W m(2) K and in the case of vertical straws h=16 ± 2.48 W m(2) K. The numerical simulation validated against experimental measurements, combined with accurate h values provides a reliable tool for the prediction of freezing curves of semen-filled straws immersed in nitrogen vapor. The present study contributes to the understanding of the cryopreservation techniques for sperm freezing based on engineering concepts, improving the cooling protocols and the manipulation of the straws.

Influence of Three Permeable Pavement Surfaces on Nitrogen Treatment

Science.gov (United States)

Nitrogen is a stressor of concern in many nutrient sensitive watersheds often associated with algal blooms and resulting fish kills. Communities are increasingly installing green infrastructure stormwater control measures (SCMs) to reduce pollutant loads associated with stormwat...

Acidification and Nitrogen Eutrophication of Austrian Forest Soils

Directory of Open Access Journals (Sweden)

Robert Jandl

2012-01-01

Full Text Available We evaluated the effect of acidic deposition and nitrogen on Austrian forests soils. Until thirty years ago air pollution had led to soil acidification, and concerns on the future productivity of forests were raised. Elevated rates of nitrogen deposition were believed to cause nitrate leaching and imbalanced forest nutrition. We used data from a soil monitoring network to evaluate the trends and current status of the pH and the C : N ratio of Austrian forest soils. Deposition measurements and nitrogen contents of Norway spruce needles and mosses were used to assess the nitrogen supply. The pH values of soils have increased because of decreasing proton depositions caused by reduction of emissions. The C : N ratio of Austrian forest soils is widening. Despite high nitrogen deposition rates the increase in forest stand density and productivity has increased the nitrogen demand. The Austrian Bioindicator Grid shows that forest ecosystems are still deficient in nitrogen. Soils retain nitrogen efficiently, and nitrate leaching into the groundwater is presently not a large-scale problem. The decline of soil acidity and the deposition of nitrogen together with climate change effects will further increase the productivity of the forests until a limiting factor such as water scarcity becomes effective.

Nitrogen in rock: Occurrences and biogeochemical implications

Science.gov (United States)

Holloway, J.M.; Dahlgren, R.A.

2002-01-01

There is a growing interest in the role of bedrock in global nitrogen cycling and potential for increased ecosystem sensitivity to human impacts in terrains with elevated background nitrogen concentrations. Nitrogen-bearing rocks are globally distributed and comprise a potentially large pool of nitrogen in nutrient cycling that is frequently neglected because of a lack of routine analytical methods for quantification. Nitrogen in rock originates as organically bound nitrogen associated with sediment, or in thermal waters representing a mixture of sedimentary, mantle, and meteoric sources of nitrogen. Rock nitrogen concentrations range from trace levels (>200 mg N kg -1) in granites to ecologically significant concentrations exceeding 1000 mg N kg -1 in some sedimentary and metasedimentary rocks. Nitrate deposits accumulated in arid and semi-arid regions are also a large potential pool. Nitrogen in rock has a potentially significant impact on localized nitrogen cycles. Elevated nitrogen concentrations in water and soil have been attributed to weathering of bedrock nitrogen. In some environments, nitrogen released from bedrock may contribute to nitrogen saturation of terrestrial ecosystems (more nitrogen available than required by biota). Nitrogen saturation results in leaching of nitrate to surface and groundwaters, and, where soils are formed from ammonium-rich bedrock, the oxidation of ammonium to nitrate may result in soil acidification, inhibiting revegetation in certain ecosystems. Collectively, studies presented in this article reveal that geologic nitrogen may be a large and reactive pool with potential for amplification of human impacts on nitrogen cycling in terrestrial and aquatic ecosystems.

Bioturbation: impact on the marine nitrogen cycle.

Science.gov (United States)

Laverock, Bonnie; Gilbert, Jack A; Tait, Karen; Osborn, A Mark; Widdicombe, Steve

2011-01-01

Sediments play a key role in the marine nitrogen cycle and can act either as a source or a sink of biologically available (fixed) nitrogen. This cycling is driven by a number of microbial remineralization reactions, many of which occur across the oxic/anoxic interface near the sediment surface. The presence and activity of large burrowing macrofauna (bioturbators) in the sediment can significantly affect these microbial processes by altering the physicochemical properties of the sediment. For example, the building and irrigation of burrows by bioturbators introduces fresh oxygenated water into deeper sediment layers and allows the exchange of solutes between the sediment and water column. Burrows can effectively extend the oxic/anoxic interface into deeper sediment layers, thus providing a unique environment for nitrogen-cycling microbial communities. Recent studies have shown that the abundance and diversity of micro-organisms can be far greater in burrow wall sediment than in the surrounding surface or subsurface sediment; meanwhile, bioturbated sediment supports higher rates of coupled nitrification-denitrification reactions and increased fluxes of ammonium to the water column. In the present paper we discuss the potential for bioturbation to significantly affect marine nitrogen cycling, as well as the molecular techniques used to study microbial nitrogen cycling communities and directions for future study.

Mean age distribution of inorganic soil-nitrogen

Science.gov (United States)

Woo, Dong K.; Kumar, Praveen

2016-07-01

Excess reactive nitrogen in soils of intensively managed landscapes causes adverse environmental impact, and continues to remain a global concern. Many novel strategies have been developed to provide better management practices and, yet, the problem remains unresolved. The objective of this study is to develop a model to characterize the "age" of inorganic soil-nitrogen (nitrate, and ammonia/ammonium). We use the general theory of age, which provides an assessment of the time elapsed since inorganic nitrogen has been introduced into the soil system. We analyze a corn-corn-soybean rotation, common in the Midwest United States, as an example application. We observe two counter-intuitive results: (1) the mean nitrogen age in the topsoil layer is relatively high; and (2) mean nitrogen age is lower under soybean cultivation compared to corn although no fertilizer is applied for soybean cultivation. The first result can be explained by cation-exchange of ammonium that retards the leaching of nitrogen, resulting in an increase in the mean nitrogen age near the soil surface. The second result arises because the soybean utilizes the nitrogen fertilizer left from the previous year, thereby removing the older nitrogen and reducing mean nitrogen age. Estimating the mean nitrogen age can thus serve as an important tool to disentangle complex nitrogen dynamics by providing a nuanced characterization of the time scales of soil-nitrogen transformation and transport processes.

The Modeling of Nitrogen Mass Transport in CoCr Alloys

Directory of Open Access Journals (Sweden)

Petraitienė Akvilė

2016-12-01

Full Text Available The kinetics of plasma nitriding of CoCr alloy below temperatures of nitrides formation and mechanisms of nitrogen penetration are analyzed by proposed kinetic modeling in this article. Proposed nitrogen diffusion model is based on the trapping – detrapping (TD model and developed taking into account the effect of the concentration dependent diffusivity of nitrogen, nitrogen adsorption on the surface of alloy and surface swelling process. The model indicates the influence of chromium atoms to nitrogen atoms diffusivity. The model consists of time and depth dependent diffusion, which is described by a partial differential equation, and it is solved by using Crank – Nicolson finite difference method. By fitting of experimental nitrogen depth profiles, it is shown that nitrogen diffusion coefficient varies with nitrogen concentration according to Einstein-Smoluchowski relation. Nitrogen depth profiles in plasma nitrided medical grade CoCr alloy (ISO 5831 – 12 at T = 400 °C for 1, 4 and 20 hours calculated on the basis of this model are in good agreement with experimental nitrogen profiles. Furthermore, the swelling process is showed and analyzed, derived the dependency of swelling rate on nitriding duration – the swelling rate is inversely proportional to the square root of nitriding duration. The obtained diffusion coefficient value and the swelling process rates satisfy the experimental data form Ref. The derived model explains physical processes during plasma nitriding and allows obtaining nitrogen depth profiles for any requisite nitriding duration.

Perfect alignment and preferential orientation of nitrogen-vacancy centers during chemical vapor deposition diamond growth on (111) surfaces

International Nuclear Information System (INIS)

Michl, Julia; Zaiser, Sebastian; Jakobi, Ingmar; Waldherr, Gerald; Dolde, Florian; Neumann, Philipp; Wrachtrup, Jörg; Teraji, Tokuyuki; Doherty, Marcus W.; Manson, Neil B.; Isoya, Junichi

2014-01-01

Synthetic diamond production is a key to the development of quantum metrology and quantum information applications of diamond. The major quantum sensor and qubit candidate in diamond is the nitrogen-vacancy (NV) color center. This lattice defect comes in four different crystallographic orientations leading to an intrinsic inhomogeneity among NV centers, which is undesirable in some applications. Here, we report a microwave plasma-assisted chemical vapor deposition diamond growth technique on (111)-oriented substrates, which yields perfect alignment (94% ± 2%) of as-grown NV centers along a single crystallographic direction. In addition, clear evidence is found that the majority (74% ± 4%) of the aligned NV centers were formed by the nitrogen being first included in the (111) growth surface and then followed by the formation of a neighboring vacancy on top. The achieved homogeneity of the grown NV centers will tremendously benefit quantum information and metrology applications

Precision management of nitrogen and water in potato production through monitoring and modelling

NARCIS (Netherlands)

Haverkort, A.J.; Vos, J.; Booij, R.

2003-01-01

Nitrogen and water application rates and timing depend on the final yield a grower expects the potato crop to achieve. Therefore precise measurements of 1) the nitrogen status of the crop and 2) the water status of the soil are needed. A crop growth model LINTUL-Potato calculates yields and the

Effects of nitrogen annealing on surface structure, silicide formation ...

Indian Academy of Sciences (India)

Effects of nitrogen annealing on structural and magnetic properties of Co/Si (100) up to 700◦C has been studied in this ... are dictated by uniformity of interdiffusion parallel to inter- ..... AFM images confirmed increase in the nanocrystalline.

Nitrogen concentration estimation with hyperspectral LiDAR

Directory of Open Access Journals (Sweden)

O. Nevalainen

2013-10-01

Full Text Available Agricultural lands have strong impact on global carbon dynamics and nitrogen availability. Monitoring changes in agricultural lands require more efficient and accurate methods. The first prototype of a full waveform hyperspectral Light Detection and Ranging (LiDAR instrument has been developed at the Finnish Geodetic Institute (FGI. The instrument efficiently combines the benefits of passive and active remote sensing sensors. It is able to produce 3D point clouds with spectral information included for every point which offers great potential in the field of remote sensing of environment. This study investigates the performance of the hyperspectral LiDAR instrument in nitrogen estimation. The investigation was conducted by finding vegetation indices sensitive to nitrogen concentration using hyperspectral LiDAR data and validating their performance in nitrogen estimation. The nitrogen estimation was performed by calculating 28 published vegetation indices to ten oat samples grown in different fertilization conditions. Reference data was acquired by laboratory nitrogen concentration analysis. The performance of the indices in nitrogen estimation was determined by linear regression and leave-one-out cross-validation. The results indicate that the hyperspectral LiDAR instrument holds a good capability to estimate plant biochemical parameters such as nitrogen concentration. The instrument holds much potential in various environmental applications and provides a significant improvement to the remote sensing of environment.

Transformation of nitrogen and distribution of nitrogen-related bacteria in a polluted urban stream.

Science.gov (United States)

Jiao, Y; Jin, W B; Zhao, Q L; Zhang, G D; Yan, Y; Wan, J

2009-01-01

Most researchers focused on either nitrogen species or microbial community for polluted urban stream while ignoring the interaction between them and its effect on nitrogen transformation, which restricted the rational selection of an effective and feasible remediation technology. Taking Buji stream in Shenzhen (China) as target stream, the distribution of nitrogen-related bacteria was investigated by most probable number (MPN) besides analysis of nitrogen species etc. The nitrogen-related bacteria in sediment were 10(2) times richer than those in water. Owing to their faster growth, the MPN of ammonifying bacteria and denitrifying bacteria were 10(5) and 10(2) times higher than those of nitrifying bacteria, respectively. The ammonifying bacteria numbers were significantly related to BOD5 in water, while nitrifying bacteria in sediment correlated well with nitrate in water. Thus, nitrification occurred mainly in sediment surface and was limited by low proportion of nitrifying bacteria. The denitrifying bacteria in sediment had good relationship with BOD5 and nitrite and nitrate in water. Low DO and rich organic compounds were beneficial to denitrification but unfavourable to nitrification. Denitrification was restricted by low nitrite and nitrate concentration. These results could be served as a reference for implementing the remediation scheme of nitrogen polluted urban stream.

Ground cover and tree growth on calcareous minesoils: Greater influence of soil surface than nitrogen rate or seed mix

International Nuclear Information System (INIS)

Kost, D.A.; Vimmerstedt, J.P.

1994-01-01

Growth of ground cover and trees was evaluated for five growing seasons on calcareous coal minesoil surfaces (standard graded topsoil, graded and ripped topsoil, graded gray cast overburden) in southeastern Ohio. Soil surface plots were seeded in September 1987 with either a standard herbaceous seed mix [orchardgrass (Dactylis glomerata L.), timothy (Phleum pratense L.), perennial ryegrass (Lolium perenne L.), Kentucky bluegrass (Poa pratensis L.), Ranger alfalfa (Medicago sativa L.), Mammoth red clover (Trifolium pratense L.), Empire birdsfoot trefoil (Lotus corniculatus L.), and wheat (Triticum aestivum L.)], or a modified mix using no alfalfa and half the rate of orchardgrass. Nitrogen (45, 90, or 135 kg ha/N) was applied as ammonium nitrate in September 1987 and April 1989. White ash (Fraxinus americana L.), silver maple (Acer saccharinum L.), northern red oak (Quercus rubra L.), and eastern white pine (Pinus strobus L.) were planted in spring 1989 into 0.8 m-wide strips sprayed with glyphosate herbicide at 2.24 kg/ha in October 1988. Total cover and total biomass were highest in July 1989, following the last application of nitrogen fertilizer in April 1989. Total cover ranged from 44% to 56%, and total biomass ranged from 102 to 162 g/0.5 m 2 from 1990 to 1993. Total cover and total biomass were lower at the lowest nitrogen rate in 1989 only. Type of herbaceous seed mix did not affect growth of ground cover or trees. Overall tree survival was 82.0% the first year but declined to 40.6% after 5 yr. Survival varied significantly among all tree species (3.5% for pine, 22.2% for oak, 38.5% for maple, 98.1% for ash)

Monthly Sea Surface Salinity and Freshwater Flux Monitoring

Science.gov (United States)

Ren, L.; Xie, P.; Wu, S.

2017-12-01

Taking advantages of the complementary nature of the Sea Surface Salinity (SSS) measurements from the in-situ (CTDs, shipboard, Argo floats, etc.) and satellite retrievals from Soil Moisture Ocean Salinity (SMOS) satellite of the European Space Agency (ESA), the Aquarius of a joint venture between US and Argentina, and the Soil Moisture Active Passive (SMAP) of national Aeronautics and Space Administration (NASA), a technique is developed at NOAA/NCEP/CPC to construct an analysis of monthly SSS, called the NOAA Blended Analysis of Sea-Surface Salinity (BASS). The algorithm is a two-steps approach, i.e. to remove the bias in the satellite data through Probability Density Function (PDF) matching against co-located in situ measurements; and then to combine the bias-corrected satellite data with the in situ measurements through the Optimal Interpolation (OI) method. The BASS SSS product is on a 1° by 1° grid over the global ocean for a 7-year period from 2010. Combined with the NOAA/NCEP/CPC CMORPH satellite precipitation (P) estimates and the Climate Forecast System Reanalysis (CFSR) evaporation (E) fields, a suite of monthly package of the SSS and oceanic freshwater flux (E and P) was developed to monitor the global oceanic water cycle and SSS on a monthly basis. The SSS in BASS product is a suite of long-term SSS and fresh water flux data sets with temporal homogeneity and inter-component consistency better suited for the examination of the long-term changes and monitoring. It presents complete spatial coverage and improved resolution and accuracy, which facilitates the diagnostic analysis of the relationship and co-variability among SSS, freshwater flux, mixed layer processes, oceanic circulation, and assimilation of SSS into global models. At the AGU meeting, we will provide more details on the CPC salinity and fresh water flux data package and its applications in the monitoring and analysis of SSS variations in association with the ENSO and other major climate

Catalytic synthesis of ammonia using vibrationally excited nitrogen molecules

DEFF Research Database (Denmark)

Hansen, Flemming Yssing; Henriksen, Niels Engholm; Billing, Gert D.

1992-01-01

The dissociation of nitrogen is the rate-limiting step in the catalytic synthesis of ammonia. Theoretical calculations have shown that the dissociative sticking probability of molecular nitrogen on catalytic active metal surfaces is enhanced by orders of magnitude when the molecules...

Effect of nitrogen addition on the performance of microbial fuel cell anodes

KAUST Repository

Saito, Tomonori

2011-01-01

Carbon cloth anodes were modified with 4(N,N-dimethylamino)benzene diazonium tetrafluoroborate to increase nitrogen-containing functional groups at the anode surface in order to test whether the performance of microbial fuel cells (MFCs) could be improved by controllably modifying the anode surface chemistry. Anodes with the lowest extent of functionalization, based on a nitrogen/carbon ratio of 0.7 as measured by XPS, achieved the highest power density of 938mW/m2. This power density was 24% greater than an untreated anode, and similar to that obtained with an ammonia gas treatment previously shown to increase power. Increasing the nitrogen/carbon ratio to 3.8, however, decreased the power density to 707mW/m2. These results demonstrate that a small amount of nitrogen functionalization on the carbon cloth material is sufficient to enhance MFC performance, likely as a result of promoting bacterial adhesion to the surface without adversely affecting microbial viability or electron transfer to the surface. © 2010 Elsevier Ltd.

Corn yield and economic return with nitrogen applied through drip tubing

Science.gov (United States)

A two year project was established to determine corn (Zea mays, L) yield response to subsurface (SSDI) and surface (SDI) drip irrigation systems at various nitrogen fertilizer rates. Nitrogen was applied through the drip system at two nitrogen levels in three split applications. Supplemental dry N ...

Rapid monitoring of intermediate states and mass balance of nitrogen during denitrification by means of cavity enhanced Raman multi-gas sensing

Energy Technology Data Exchange (ETDEWEB)

Keiner, Robert [Institute of Physical Chemistry, Friedrich Schiller University Jena, Jena 07743 (Germany); Leibniz Institute of Photonic Technology, Jena 07745 (Germany); Herrmann, Martina; Küsel, Kirsten [Institute of Ecology, Friedrich Schiller University Jena, Jena 07743 (Germany); German Centre for Integrative Biodiversity Research (iDiv) Halle–Jena–Leipzig, Leipzig 04103 (Germany); Popp, Jürgen [Institute of Physical Chemistry, Friedrich Schiller University Jena, Jena 07743 (Germany); Leibniz Institute of Photonic Technology, Jena 07745 (Germany); InfectoGnostics Forschungscampus, Zentrum für Angewandte Forschung, Jena 07743 (Germany); Abbe School of Photonics, Friedrich Schiller University, Jena (Germany); Frosch, Torsten, E-mail: torsten.frosch@uni-jena.de [Institute of Physical Chemistry, Friedrich Schiller University Jena, Jena 07743 (Germany); Leibniz Institute of Photonic Technology, Jena 07745 (Germany); InfectoGnostics Forschungscampus, Zentrum für Angewandte Forschung, Jena 07743 (Germany)

2015-03-15

Highlights: • CERS is a versatile new analytical methodology. • Continuous online quantification of reduction of {sup 15}N-labelled nitrate by P. stutzeri was demonstrated. • The total nitrogen element budget was monitored online for the first time. • Sterile online acquisition of the pH changes in the P. stutzeri culture was demonstrated. • An increased slope of the pH value coincided with a temporary accumulation of N{sub 2}O. - Abstract: The comprehensive investigation of changes in N cycling has been challenging so far due to difficulties with measuring gases such as N{sub 2} and N{sub 2}O simultaneously. In this study we introduce cavity enhanced Raman gas spectroscopy as a new analytical methodology for tracing the stepwise reduction of {sup 15}N-labelled nitrate by the denitrifying bacteria Pseudomonas stutzeri. The unique capabilities of Raman multi-gas analysis enabled real-time, continuous, and non-consumptive quantification of the relevant gases ({sup 14}N{sub 2}, {sup 14}N{sub 2}O, O{sub 2}, and CO{sub 2}) and to trace the fate of {sup 15}N-labeled nitrate substrate ({sup 15}N{sub 2}, {sup 15}N{sub 2}O) added to a P. stutzeri culture with one single measurement. Using this new methodology, we could quantify the kinetics of the formation and degradation for all gaseous compounds (educts and products) and thus study the reaction orders. The gas quantification was complemented with the analysis of nitrate and nitrite concentrations for the online monitoring of the total nitrogen element budget. The simultaneous quantification of all gases also enabled the contactless and sterile online acquisition of the pH changes in the P. stutzeri culture by the stoichiometry of the redox reactions during denitrification and the CO{sub 2}-bicarbonate equilibrium. Continuous pH monitoring – without the need to insert an electrode into solution – elucidated e.g. an increase in the slope of the pH value coinciding with an accumulation of nitrite, which in

Air pollution monitoring in Amman, Jordan

International Nuclear Information System (INIS)

Al-Hasaan, A.A.; Dann, T.F.; Brunet, P.F.

1992-01-01

In 1985, a collaborative research program was established between the Royal Scientific Society of Jordan and Environment Canada, Pollution Measurement Division, Ottawa, Canada, with the objective of developing an air pollution monitoring network for Amman and preparing recommendations for national air quality standards and national emission standards for Jordan. Four monitoring sites were established in residential and commercial areas of Amman. Carbon monoxide, nitrogen dioxide, sulphur dioxide and total suspended particle matter (TSP) were measured at the Downtown station. At the other sites only TSP was measured. A short-term monitoring program carried out with a mobile monitoring unit showed relatively low levels of sulfur dioxide, carbon monoxide and nitrogen dioxide at the RSS, Naser and Marka sites as compared to the Downtown site. Continuous analyzers purchased from Environment SA, France, were used to measure sulfur dioxide, carbon monoxide and nitrogen dioxide; Sierra-Anderson high volume samplers equipped with glass fiber filters were used to collect total suspended particulates samples. Gaseous pollutants were continuously measured at the Downtown site and TSP samplers were operated on a three day schedule at all sites. Sampling began in July 1986 and continues to the present

XPS study of the passive films formed on nitrogen-implanted austenitic stainless steels

International Nuclear Information System (INIS)

Marcus, P.; Bussell, M.E.

1992-01-01

Austenitic stainless steels (304-type) have been implanted with nitrogen ions in order to investigate the effects of implanted nitrogen on their electrochemical behaviour and on the nature of the passive film formed on the steels in acid (0.5M H 2 SO 4 ). Alloys with two nitrogen doses have been prepared (2.5x10 16 and 2x10 17 N atoms/cm 2 ). The implanted alloys have been characterized by 15 N-NRA (nuclear reaction analysis) and XPS (X-ray photoelectron spectroscopy). Alloy surfaces with well-defined N concentrations were prepared, prior to the electrochemical measurements, by argon-ion sputtering of the implanted material for a fixed time in order to reach a well-defined point on the nitrogen depth profile. The samples were then transferred without exposure to air to an electrochemical cell mounted in an inert gas glove box. The implanted nitrogen modifies the electrochemical behaviour of the alloy. The anodic dissolution in the active state is enhanced, and the current density in the passive state is increased. Surface analysis of the alloys by XPS after passivation shows that implanted nitrogen is enriched on the surface during dissolution and passivation of the alloys. The process by which N is enriched on the surface is anodic segregation, which was first observed and characterized for S on Ni and Ni-Fe alloys. The passive films formed on both the unimplanted and implanted alloys have a bilayer structure with an inner oxide layer and an outer hydroxide layer, but on the nitrogen-implanted alloy, a chromium nitride phase is formed at the expense of the chromium oxide. After passivation of the implanted alloys, three chemical states of nitrogen are detected in the N 1s spectrum. The high binding energy (399.4 eV) peak corresponds to a nitrogen species located on the surface of the passive film, which is produced by reaction of the implanted nitrogen with the solution. (orig./WL)

Nitrogen solubility in the deep mantle and the origin of Earth's primordial nitrogen budget

Science.gov (United States)

Yoshioka, Takahiro; Wiedenbeck, Michael; Shcheka, Svyatoslav; Keppler, Hans

2018-04-01

be modeled. Such models show that if the magma ocean coexisted with a primordial atmosphere having a nitrogen partial pressure of just a few bars, several times the current atmospheric mass of nitrogen must have been trapped in the deep mantle. It is therefore plausible that the apparent depletion of nitrogen relative to other volatiles in the near-surface reservoirs reflects the storage of a larger reservoir of nitrogen in the solid Earth. Dynamic exchange between these reservoirs may have induced major fluctuations of bulk atmospheric pressure over Earth's history.

Incorporating Prognostic Marine Nitrogen Fixers and Related Bio-Physical Feedbacks in an Earth System Model

Science.gov (United States)

Paulsen, H.; Ilyina, T.; Six, K. D.

2016-02-01

Marine nitrogen fixers play a fundamental role in the oceanic nitrogen and carbon cycles by providing a major source of `new' nitrogen to the euphotic zone that supports biological carbon export and sequestration. Furthermore, nitrogen fixers may regionally have a direct impact on ocean physics and hence the climate system as they form extensive surface mats which can increase light absorption and surface albedo and reduce the momentum input by wind. Resulting alterations in temperature and stratification may feed back on nitrogen fixers' growth itself.We incorporate nitrogen fixers as a prognostic 3D tracer in the ocean biogeochemical component (HAMOCC) of the Max Planck Institute Earth system model and assess for the first time the impact of related bio-physical feedbacks on biogeochemistry and the climate system.The model successfully reproduces recent estimates of global nitrogen fixation rates, as well as the observed distribution of nitrogen fixers, covering large parts of the tropical and subtropical oceans. First results indicate that including bio-physical feedbacks has considerable effects on the upper ocean physics in this region. Light absorption by nitrogen fixers leads locally to surface heating, subsurface cooling, and mixed layer depth shoaling in the subtropical gyres. As a result, equatorial upwelling is increased, leading to surface cooling at the equator. This signal is damped by the effect of the reduced wind stress due to the presence of cyanobacteria mats, which causes a reduction in the wind-driven circulation, and hence a reduction in equatorial upwelling. The increase in surface albedo due to nitrogen fixers has only inconsiderable effects. The response of nitrogen fixers' growth to the alterations in temperature and stratification varies regionally. Simulations with the fully coupled Earth system model are in progress to assess the implications of the biologically induced changes in upper ocean physics for the global climate system.

Analysis of cutting force signals by wavelet packet transform for surface roughness monitoring in CNC turning

Science.gov (United States)

García Plaza, E.; Núñez López, P. J.

2018-01-01

On-line monitoring of surface finish in machining processes has proven to be a substantial advancement over traditional post-process quality control techniques by reducing inspection times and costs and by avoiding the manufacture of defective products. This study applied techniques for processing cutting force signals based on the wavelet packet transform (WPT) method for the monitoring of surface finish in computer numerical control (CNC) turning operations. The behaviour of 40 mother wavelets was analysed using three techniques: global packet analysis (G-WPT), and the application of two packet reduction criteria: maximum energy (E-WPT) and maximum entropy (SE-WPT). The optimum signal decomposition level (Lj) was determined to eliminate noise and to obtain information correlated to surface finish. The results obtained with the G-WPT method provided an in-depth analysis of cutting force signals, and frequency ranges and signal characteristics were correlated to surface finish with excellent results in the accuracy and reliability of the predictive models. The radial and tangential cutting force components at low frequency provided most of the information for the monitoring of surface finish. The E-WPT and SE-WPT packet reduction criteria substantially reduced signal processing time, but at the expense of discarding packets with relevant information, which impoverished the results. The G-WPT method was observed to be an ideal procedure for processing cutting force signals applied to the real-time monitoring of surface finish, and was estimated to be highly accurate and reliable at a low analytical-computational cost.

Application of the wavelet packet transform to vibration signals for surface roughness monitoring in CNC turning operations

Science.gov (United States)

García Plaza, E.; Núñez López, P. J.

2018-01-01

The wavelet packet transform method decomposes a time signal into several independent time-frequency signals called packets. This enables the temporary location of transient events occurring during the monitoring of the cutting processes, which is advantageous in monitoring condition and fault diagnosis. This paper proposes the monitoring of surface roughness using a single low cost sensor that is easily implemented in numerical control machine tools in order to make on-line decisions on workpiece surface finish quality. Packet feature extraction in vibration signals was applied to correlate the sensor signals to measured surface roughness. For the successful application of the WPT method, mother wavelets, packet decomposition level, and appropriate packet selection methods should be considered, but are poorly understood aspects in the literature. In this novel contribution, forty mother wavelets, optimal decomposition level, and packet reduction methods were analysed, as well as identifying the effective frequency range providing the best packet feature extraction for monitoring surface finish. The results show that mother wavelet biorthogonal 4.4 in decomposition level L3 with the fusion of the orthogonal vibration components (ax + ay + az) were the best option in the vibration signal and surface roughness correlation. The best packets were found in the medium-high frequency DDA (6250-9375 Hz) and high frequency ADA (9375-12500 Hz) ranges, and the feed acceleration component ay was the primary source of information. The packet reduction methods forfeited packets with relevant features to the signal, leading to poor results for the prediction of surface roughness. WPT is a robust vibration signal processing method for the monitoring of surface roughness using a single sensor without other information sources, satisfactory results were obtained in comparison to other processing methods with a low computational cost.

The effect of Ti and Nb on nitrogen dissolution reaction in stainless steel melt

International Nuclear Information System (INIS)

Jang, Min Whan; Hong, In Kook; Pak, Jong Jin; Song, Hyo Seok; Lee, Yong Deuk

2002-01-01

A kinetic study of nitrogen dissolution in STS304 stainless steel melt containing Ti and Nb has been carried out at 1500 degree C using an induction furnace and a levitation melting furnace. At low O and S levels, the nitrogen dissolution rate showed the first-order kinetics being controlled by the mass transfer of nitrogen in the melt. Ti addition to STS304 stainless melt significantly retarded the nitrogen dissolution rate by the formation of solid Ti oxide layer adhered on the melt surface. Nb did not affect the rate of nitrogen dissolution. In the levitation melting experiment where the oxide layer was removed from the melt surface, Ti did not retard the nitrogen dissolution rate. Simultaneous addition of Ti and Al increased the dissolution rate by the formation of non-wetting Al 2 O 3 on the melt surface. A small addition of CaO-Al 2 O 3 synthetic flux to Ti containing melt was very effective to remove the oxide layer, hence to increase the nitrogen dissolution rate

The effect of Ti and Nb on nitrogen dissolution reaction in stainless steel melt

Energy Technology Data Exchange (ETDEWEB)

Jang, Min Whan; Hong, In Kook; Pak, Jong Jin [Hanyang Univ., Ansan (Korea, Republic of); Song, Hyo Seok; Lee, Yong Deuk [POSCO, Pohang (Korea, Republic of)

2002-03-01

A kinetic study of nitrogen dissolution in STS304 stainless steel melt containing Ti and Nb has been carried out at 1500 degree C using an induction furnace and a levitation melting furnace. At low O and S levels, the nitrogen dissolution rate showed the first-order kinetics being controlled by the mass transfer of nitrogen in the melt. Ti addition to STS304 stainless melt significantly retarded the nitrogen dissolution rate by the formation of solid Ti oxide layer adhered on the melt surface. Nb did not affect the rate of nitrogen dissolution. In the levitation melting experiment where the oxide layer was removed from the melt surface, Ti did not retard the nitrogen dissolution rate. Simultaneous addition of Ti and Al increased the dissolution rate by the formation of non-wetting Al{sub 2}O{sub 3} on the melt surface. A small addition of CaO-Al{sub 2}O{sub 3} synthetic flux to Ti containing melt was very effective to remove the oxide layer, hence to increase the nitrogen dissolution rate.

Pesticide monitoring in surface water and groundwater using passive samplers

Science.gov (United States)

Kodes, V.; Grabic, R.

2009-04-01

Passive samplers as screening devices have been used within a czech national water quality monitoring network since 2002 (SPMD and DGT samplers for non polar substances and metals). The passive sampler monitoring of surface water was extended to polar substances, in 2005. Pesticide and pharmaceutical POCIS samplers have been exposed in surface water at 21 locations and analysed for polar pesticides, perfluorinated compounds, personal care products and pharmaceuticals. Pesticide POCIS samplers in groundwater were exposed at 5 locations and analysed for polar pesticides. The following active substances of plant protection products were analyzed in surface water and groundwater using LC/MS/MS: 2,4,5-T, 2,4-D, Acetochlor, Alachlor, Atrazine, Atrazine_desethyl, Azoxystrobin, Bentazone, Bromacil, Bromoxynil, Carbofuran, Clopyralid, Cyanazin, Desmetryn, Diazinon, Dicamba, Dichlobenil, Dichlorprop, Dimethoat, Diuron, Ethofumesate, Fenarimol, Fenhexamid, Fipronil, Fluazifop-p-butyl, Hexazinone, Chlorbromuron, Chlorotoluron, Imazethapyr, Isoproturon, Kresoxim-methyl, Linuron, MCPA, MCPP, Metalaxyl, Metamitron, Methabenzthiazuron, Methamidophos, Methidathion, Metobromuron, Metolachlor, Metoxuron, Metribuzin, Monolinuron, Nicosulfuron, Phorate, Phosalone, Phosphamidon, Prometryn, Propiconazole, Propyzamide, Pyridate, Rimsulfuron, Simazine, Tebuconazole, Terbuthylazine, Terbutryn, Thifensulfuron-methyl, Thiophanate-methyl and Tri-allate. The POCIS samplers performed very well being able to provide better picture than grab samples. The results show that polar pesticides and also perfluorinated compounds, personal care products and pharmaceuticals as well occur in hydrosphere of the Czech republic. Acknowledgment: Authors acknowledge the financial support of grant No. 2B06095 by the Ministry of Education, Youth and Sports.

The geobiological nitrogen cycle: From microbes to the mantle.

Science.gov (United States)

Zerkle, A L; Mikhail, S

2017-05-01

Nitrogen forms an integral part of the main building blocks of life, including DNA, RNA, and proteins. N 2 is the dominant gas in Earth's atmosphere, and nitrogen is stored in all of Earth's geological reservoirs, including the crust, the mantle, and the core. As such, nitrogen geochemistry is fundamental to the evolution of planet Earth and the life it supports. Despite the importance of nitrogen in the Earth system, large gaps remain in our knowledge of how the surface and deep nitrogen cycles have evolved over geologic time. Here, we discuss the current understanding (or lack thereof) for how the unique interaction of biological innovation, geodynamics, and mantle petrology has acted to regulate Earth's nitrogen cycle over geologic timescales. In particular, we explore how temporal variations in the external (biosphere and atmosphere) and internal (crust and mantle) nitrogen cycles could have regulated atmospheric pN 2 . We consider three potential scenarios for the evolution of the geobiological nitrogen cycle over Earth's history: two in which atmospheric pN 2 has changed unidirectionally (increased or decreased) over geologic time and one in which pN 2 could have taken a dramatic deflection following the Great Oxidation Event. It is impossible to discriminate between these scenarios with the currently available models and datasets. However, we are optimistic that this problem can be solved, following a sustained, open-minded, and multidisciplinary effort between surface and deep Earth communities. © 2017 The Authors Geobiology Published by John Wiley & Sons Ltd.

84 K nitrogen system for the SSC

International Nuclear Information System (INIS)

McAshan, M.; Thirumaleshwar, M.; Abramovich, S.; Ganni, V.; Scheidemantle, A.

1992-01-01

The nitrogen system for the Superconducting Super Collider (SSC) is designed to provide the 84 K (nominal) shield refrigeration for the collider rings. Liquid nitrogen is supplied to the collider tunnel from one, two, or more locations on the surface through the service shafts and is distributed along, the 87 km of both rings by the 84 K shield lines. Additional design requirements for the nitrogen distribution system include precooling, fluid supply to the helium plants, supplying makeup liquid nitrogen to the reservoirs located at the entrance of the main shafts, and providing an efficient cooldown means for the cold mass from 300 K to 90 K. The operational modes and possible emergency and maintenance conditions of the collider are taken into account for the nitrogen system design. The status of our work, including design considerations that address thermal aspects (heat load, recooling scheme, etc.) and hydraulic aspects (pressures, elevations, distances, etc.) of the nitrogen system will be discussed

Discussion: some new findings from surface subsidence monitoring over longwall panels

International Nuclear Information System (INIS)

Luo, Y.; Peng, S.S.; Arioglu, E.

1992-01-01

The article consists of a discussion of the paper, 'some new findings from surface subsidence monitoring over longwall panels' and a reply by the paper's authors, Luo and Peng. The reviewer, Arioglu, regards the paper favourably but suggests that surface subsidence can be represented by an exponential expression, and that there is a regression equation linking possible subsidence, pillar loading and the height-to-width ratio of the pillars left. Luo and Peng reply with their reasons for preferring their original linear regression model to the non-linear models suggested by Arioglu. 4 figs

A Continuous Flow System for the Measurement of Ambient Nitrogen Oxides [NO + NO] Using Rhodamine B Hydrazide as a Chemosensor

Directory of Open Access Journals (Sweden)

Pandurangappa Malingappa

2014-01-01

Full Text Available A new chemosensor has been used to monitor atmospheric nitrogen oxides [NO + NO 2 ] at parts per billion (ppb level. It is based on the catalytic reaction of nitrogen oxides with rhodamine B hydrazide (RBH to produce a colored compound through the hydrolysis of the amide bond of the molecule. A simple colorimeter has been used to monitor atmospheric nitrogen dioxide at ppb level. The air samples were purged through a sampling cuvette containing RBH solution using peristaltic pump. The proposed method has been successfully applied to monitor the ambient nitrogen dioxide levels at traffic junction points within the city limits and the results obtained are compared with the standard Griess-Ilosvay method.

Observational Effects of Magnetism in O Stars: Surface Nitrogen Abundances

Science.gov (United States)

Martins, F.; Escolano, C.; Wade, G. A.; Donati, J. F.; Bouret, J. C.

2011-01-01

Aims. We investigate the surface nitrogen content of the six magnetic O stars known to date as well as of the early B-type star Tau Sco.. We compare these abundances to predictions of evolutionary models to isolate the effects of magnetic field on the transport of elements in stellar interiors. Methods. We conduct a quantitative spectroscopic analysis of the ample stars with state-of-the-art atmosphere models. We rely on high signal-to-noise ratio, high resolution optical spectra obtained with ESPADONS at CFHT and NARVAL at TBL. Atmosphere models and synthetic spectra are computed with the code CMFGEN. Values of N/H together with their uncertainties are determined and compared to predictions of evolutionary models. Results. We find that the magnetic stars can be divided into two groups: one with stars displaying no N enrichment (one object); and one with stars most likely showing extra N enrichment (5 objects). For one star (Ori C) no robust conclusion can be drawn due to its young age. The star with no N enrichment is the one with the weakest magnetic field, possibly of dynamo origin. It might be a star having experienced strong magnetic braking under the condition of solid body rotation, but its rotational velocity is still relatively large. The five stars with high N content were probably slow rotators on the zero age main sequence, but they have surface N/H typical of normal O stars, indicating that the presence of a (probably fossil) magnetic field leads to extra enrichment. These stars may have a strong differential rotation inducing shear mixing. Our results shOuld be viewed as a basis on which new theoretical simulations can rely to better understand the effect of magnetism on the evolution of massive stars.

Chemical characterization of 4140 steel implanted by nitrogen ions

Energy Technology Data Exchange (ETDEWEB)

Nino, Ely Dannier V.; Duran, Fernando [Grupo de Investigacion en Tecnologia del Plasma (GINTEP), Departamento de Ciencias Basicas, Universidad Pontificia Bolivariana, Bucaramanga (Colombia); Pinto, Jose L.C. [Grupo de Investigacion en Quimica Estructural (GIQUE), Universidad Industrial de Santander, Bucaramanga (Colombia); Dugar-Zhabon, V.; Garnica, Hernan [Grupo de Fisica y Tecnologia del Plasma (FITEK), Universidad Industrial de Santander, Bucaramanga (Colombia)

2010-07-01

AISI-SAE 4140 sample surfaces of different roughness which are implanted by nitrogen ions of 20 keV and 30 keV at a dose of 10{sup 17} ions/cm{sup 2} through a three dimensional ion implantation technique are studied. Crystal phases of nitrogen compositions of the implanted samples, obtained with help of an x-ray diffraction method, are confronted with the data reported by the International Centre for Diffraction Data (ICDD), PDF-2. It is observed that the implanted into the metal nitrogen atoms produce changes in orientation of crystal planes that is manifested as variations of the intensity of the refracted rays and of cell dimensions (a displacement of 2 theta of the maximum intensity position). An analysis for determining nitrogen atoms implanted by high-voltage pulsed discharges at low pressures in the crystal structure of the solid surface was carried out by X-Ray Diffraction due to this technique permits to assess the possibility of formation of new compounds. (author)

Chemical characterization of 4140 steel implanted by nitrogen ions

International Nuclear Information System (INIS)

Nino, Ely Dannier V.; Duran, Fernando; Pinto, Jose L.C.; Dugar-Zhabon, V.; Garnica, Hernan

2010-01-01

AISI-SAE 4140 sample surfaces of different roughness which are implanted by nitrogen ions of 20 keV and 30 keV at a dose of 10"1"7 ions/cm"2 through a three dimensional ion implantation technique are studied. Crystal phases of nitrogen compositions of the implanted samples, obtained with help of an x-ray diffraction method, are confronted with the data reported by the International Centre for Diffraction Data (ICDD), PDF-2. It is observed that the implanted into the metal nitrogen atoms produce changes in orientation of crystal planes that is manifested as variations of the intensity of the refracted rays and of cell dimensions (a displacement of 2 theta of the maximum intensity position). An analysis for determining nitrogen atoms implanted by high-voltage pulsed discharges at low pressures in the crystal structure of the solid surface was carried out by X-Ray Diffraction due to this technique permits to assess the possibility of formation of new compounds. (author)

Eco-Friendly Synthesis of Nitrogen-Doped Mesoporous Carbon for Supercapacitor Application

Directory of Open Access Journals (Sweden)

Georges Moussa

2018-03-01

Full Text Available A sustainable and simple synthesis procedure involving the co-assembly of green phenolic resin and amphiphilic polymer template in water/ethanol mixture at room temperature to synthesize nitrogen doped mesoporous carbon is reported herein. Guanine is proposed as a novel nitrogen-based precursor which is able to create H-bondings both with the phenolic resin and the template allowing the formation of mesoporous carbons with nitrogen atoms uniformly distributed in their framework. The influence of the synthesis procedure, template amount and annealing temperature on the carbon textural properties, structure and surface chemistry were investigated. For several conditions, carbon materials with ordered pore size and high nitrogen content (up to 10.6 at % could be achieved. The phase separation procedure combined with optimal amount of template favor the formation of ordered mesoporous carbons with higher specific surface area while the increase in the temperature induces a decrease in the surface area and amount of heteroatoms (N and O. The electrochemical performances as electrode in supercapacitors were evaluated in acidic medium and the capacitance was closely related to the material conductivity and surface chemistry.

Surface structural evolvement in the conversion of polyacrylonitrile precursors to carbon fibers

International Nuclear Information System (INIS)

Qian, Xin; Zou, Ruifen; OuYang, Qin; Wang, Xuefei; Zhang, Yonggang

2015-01-01

Highlights: • The characteristic striated topography of PAN precursors resulted from the wet spinning process could pass down to carbon fibers. • The ridges and grooves monitored became much more well-defined after the thermo-oxidation. • Both the depth and the width of longitudinal grooves decreased after the carbonization. • Carbon, nitrogen, oxygen and silicon were the governing elements on the fiber surface. - Abstract: Surface structural evolvement in the conversion of polyacrylonitrile (PAN) precursors to carbon fibers was investigated through scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). SEM results showed that the characteristic striated topography of PAN precursors resulted from the wet spinning process could pass down to carbon fibers. The fiber diameter gradually decreased from 11.3 μm to 5.5 μm and the corresponding density increased from 1.18 g/cm 3 to 1.80 g/cm 3 in the conversion of PAN precursors to carbon fibers. The ridges and grooves monitored by AFM became much more well-defined after the thermo-oxidation. However, the original longitudinal grooves were destroyed and both the depth and the width of longitudinal grooves decreased after the carbonization. XPS results revealed that carbon, nitrogen, oxygen and silicon were the governing elements on the fiber surface. The −C−C functional groups was the dominant groups and the relative contents of −C=O and −COO groups gradually increased in the process of thermo-oxidation and carbonization

Monitoring sea level and sea surface temperature trends from ERS satellites

DEFF Research Database (Denmark)

Andersen, Ole Baltazar; Knudsen, Per; Beckley, B.

2002-01-01

Data from the two ESA satellites ERS-1 and ERS-2 are used in global and regional analysis of sea level and sea surface temperature trends over the last, 7.8 years. T he ERS satellites and in the future the ENVISAT satellite provide unique opportunity for monitoring both changes in sea level and sea...

Supercapacitors based on nitrogen-doped reduced graphene oxide and borocarbonitrides

Science.gov (United States)

Gopalakrishnan, K.; Moses, Kota; Govindaraj, A.; Rao, C. N. R.

2013-12-01

Nitrogen-doped reduced graphene oxide (RGO) samples with different nitrogen content, prepared by two different methods, as well as nitrogen-doped few-layer graphene have been investigated as supercapacitor electrodes. Two electrode measurements have been carried out both in aqueous (6M KOH) and in ionic liquid media. Nitrogen-doped reduced graphene oxides exhibit satisfactory specific capacitance, the values reaching 126F/g at a scan rate of 10mV/s in aqueous medium. Besides providing supercapacitor characteristics, the study has shown the nitrogen content and surface area to be important factors. High surface-area borocarbonitrides, BxCyNz, prepared by the urea route appear to be excellent supercapacitor electrode materials. Thus, BC4.5N exhibits a specific capacitance of 169F/g at a scan rate of 10mV/s in aqueous medium. In an ionic liquid medium, nitrogen-doped RGO and BC4.5N exhibit specific capacitance values of 258F/g and 240F/g at a scan rate of 5mV/s. The ionic liquid enables a larger operating voltage range of 0.0-2.5V compared to 0.0-1V in aqueous medium.

The Effect of Nitrogen Surface Ligands on Propane Metathesis: Design and Characterizations of N-modified SBA15-Supported Schrock-type Tungsten Alkylidyne

KAUST Repository

Eid, Ahmed A.

2014-04-01

Catalysis, which is primarily a molecular phenomenon, is an important field of chemistry because it requires the chemical conversion of molecules into other molecules. It also has an effect on many fields, including, but not limited to, industry, environment and life Science[1]. Surface Organometallic Chemistry is an effective methodology for Catalysis as it imports the concept and mechanism of organometallic chemistry, to surface science and heterogeneous catalysis. So, it bridges the gap between homogenous and heterogeneous catalysis[1]. The aim of the present research work is to study the effect of Nitrogen surface ligands on the activity of Alkane, Propane in particular, metathesis. Our approach is based on the preparation of selectively well-defined group (VI) transition metal complexes supported onto mesoporous materials, SBA15 and bearing amido and/or imido ligands. We choose nitrogen ligands because, according to the literature, they showed in some cases better catalytic properties in homogenous catalysis in comparison with their oxygen counterparts[2]. The first section covers the modification of a highly dehydroxylated SBA15 surface using a controlled ammonia treatment. These will result in the preparation of two kind of Nitrogen surface ligands: -\\tOne with vicinal silylamine/silanol, (≡SiNH2)(≡SiOH), noted [N,O]SBA15 and, -\\tAnother\\tone\\twith\\tvicinal\\tbis-silylamine moieties (≡SiNH2)2, noted [N,N]SBA15[3]. The second section covers the reaction of Schrock type Tungsten Carbyne [W(≡C- tBu)(CH2-tBu)3] with those N-surface ligands and their characterizations by FT-IR, multiple quantum solid state NMR (1H, 13C), elemental analysis and gas phase analysis. The third section covers the generation of the active site, tungsten hydride species. Their performance toward propane metathesis reaction using the dynamic reactor technique PID compared toward previous well-known catalysts supported on silica oxide or mesoporous materials[4]. A fairly good

Lunar nitrogen: Secular variation or mixing?

International Nuclear Information System (INIS)

Norris, S.J.; Wright, I.P.; Pillinger, C.T.

1986-01-01

The two current models to explain the nearly 40% variation of the lunar nitrogen isotopic composition are: (1) secular variation of solar wind nitrogen; and (2) a two component mixing model having a constant, heavy solar wind admixed with varying amounts of indigenous light lunar N (LLN). Both models are needed to explain the step pyrolysis extraction profile. The secular variation model proposes that the low temperature release is modern day solar wind implanted into grain surfaces, the 900 C to 1100 C release is from grain surfaces which were once exposed to the ancient solar wind but which are now trapped inside agglutinates, and the >1100 C release as spallogenic N produced by cosmic rays. The mixing model ascribes the components to solar wind, indigenous lunar N and spallogenic N respectively. An extension of either interpretation is that the light N seen in lunar breccias or deep drill cores represent conditions when more N-14 was available to the lunar surface

Synthesis of polybenzoxazine based nitrogen-rich porous carbons for carbon dioxide capture

Science.gov (United States)

Wan, Liu; Wang, Jianlong; Feng, Chong; Sun, Yahui; Li, Kaixi

2015-04-01

Nitrogen-rich porous carbons (NPCs) were synthesized from 1,5-dihydroxynaphthalene, urea, and formaldehyde based on benzoxazine chemistry by a soft-templating method with KOH chemical activation. They possess high surface areas of 856.8-1257.8 m2 g-1, a large pore volume of 0.15-0.65 cm3 g-1, tunable pore structure, high nitrogen content (5.21-5.32 wt%), and high char yields. The amount of the soft-templating agent F127 has multiple influences on the textural and chemical properties of the carbons, affecting the surface area and pore structure, impacting the compositions of nitrogen species and resulting in an improvement of the CO2 capture performance. At 1 bar, high CO2 uptake of 4.02 and 6.35 mmol g-1 at 25 and 0 °C was achieved for the sample NPC-2 with a molar ratio of F127 : urea = 0.010 : 1. This can be attributed to its well-developed micropore structure and abundant pyridinic nitrogen, pyrrolic nitrogen and pyridonic nitrogen functionalities. The sample NPC-2 also exhibits a remarkable selectivity for CO2/N2 separation and a fast adsorption/desorption rate and can be easily regenerated. This suggests that the polybenzoxazine-based NPCs are desirable for CO2 capture because of possessing a high micropore surface area, a large micropore volume, appropriate pore size distribution, and a large number of basic nitrogen functionalities.Nitrogen-rich porous carbons (NPCs) were synthesized from 1,5-dihydroxynaphthalene, urea, and formaldehyde based on benzoxazine chemistry by a soft-templating method with KOH chemical activation. They possess high surface areas of 856.8-1257.8 m2 g-1, a large pore volume of 0.15-0.65 cm3 g-1, tunable pore structure, high nitrogen content (5.21-5.32 wt%), and high char yields. The amount of the soft-templating agent F127 has multiple influences on the textural and chemical properties of the carbons, affecting the surface area and pore structure, impacting the compositions of nitrogen species and resulting in an improvement of the

Geomechanics for interpreting SAGD monitoring using micro-seismicity and surface tiltmeters

International Nuclear Information System (INIS)

De Pater, H.; De Koning, J.; Maxwell, S.; Walters, D.

2008-01-01

This paper described a procedures for history matching surface movements resulting from the warm-up phases of a steam assisted gravity drainage (SAGD) project in Saskatchewan. Surface movements were measured using tilt meters that covered the area influenced by the steam injection processes. A thermal reservoir model was then coupled to a geo-mechanical model in order to calculate the surface movements. Surface heave was computed by matching a minimum curvature surface to the tilt vectors. Surface heave data were extracted in order to facilitate comparisons between observed and simulated heave. Injection constraints were defined from measured injection rates in order to match pressure histories. The study showed that the coupled model accurately interpreted monitoring data. Seismic signatures indicated strike slip and potential overthrust fault slippage or casing failures. Uplift was largest at the heel of the well. Results were explained by reservoir heterogeneities. Surface heave was accurately measured using the tiltmeters. Micro-seismic data were used to constrain failure mechanisms and provide information needed to identify conformance and potential cap rock breaches. It was concluded that the model can be used effectively to optimize injection conformance and recovery. 10 refs., 4 tabs., 28 figs

Geomechanics for interpreting SAGD monitoring using micro-seismicity and surface tiltmeters

Energy Technology Data Exchange (ETDEWEB)

De Pater, H.; De Koning, J.; Maxwell, S. [Pinnacle Technologies, Calgary, AB (Canada); Walters, D. [Taurus Reservoir Solutions Ltd., Calgary, AB (Canada)

2008-10-15

This paper described a procedures for history matching surface movements resulting from the warm-up phases of a steam assisted gravity drainage (SAGD) project in Saskatchewan. Surface movements were measured using tilt meters that covered the area influenced by the steam injection processes. A thermal reservoir model was then coupled to a geo-mechanical model in order to calculate the surface movements. Surface heave was computed by matching a minimum curvature surface to the tilt vectors. Surface heave data were extracted in order to facilitate comparisons between observed and simulated heave. Injection constraints were defined from measured injection rates in order to match pressure histories. The study showed that the coupled model accurately interpreted monitoring data. Seismic signatures indicated strike slip and potential overthrust fault slippage or casing failures. Uplift was largest at the heel of the well. Results were explained by reservoir heterogeneities. Surface heave was accurately measured using the tiltmeters. Micro-seismic data were used to constrain failure mechanisms and provide information needed to identify conformance and potential cap rock breaches. It was concluded that the model can be used effectively to optimize injection conformance and recovery. 10 refs., 4 tabs., 28 figs.

A mechanistic, globally-applicable model of plant nitrogen uptake, retranslocation and fixation

Science.gov (United States)

Fisher, J. B.; Tan, S.; Malhi, Y.; Fisher, R. A.; Sitch, S.; Huntingford, C.

2008-12-01

Nitrogen is one of the nutrients that can most limit plant growth, and nitrogen availability may be a controlling factor on biosphere responses to climate change. We developed a plant nitrogen assimilation model based on a) advective transport through the transpiration stream, b) retranslocation whereby carbon is expended to resorb nitrogen from leaves, c) active uptake whereby carbon is expended to acquire soil nitrogen, and d) biological nitrogen fixation whereby carbon is expended for symbiotic nitrogen fixers. The model relies on 9 inputs: 1) net primary productivity (NPP), 2) plant C:N ratio, 3) available soil nitrogen, 4) root biomass, 5) transpiration rate, 6) saturated soil depth,7) leaf nitrogen before senescence, 8) soil temperature, and 9) ability to fix nitrogen. A carbon cost of retranslocation is estimated based on leaf nitrogen and compared to an active uptake carbon cost based on root biomass and available soil nitrogen; for nitrogen fixers both costs are compared to a carbon cost of fixation dependent on soil temperature. The NPP is then allocated to optimize growth while maintaining the C:N ratio. The model outputs are total plant nitrogen uptake, remaining NPP available for growth, carbon respired to the soil and updated available soil nitrogen content. We test and validate the model (called FUN: Fixation and Uptake of Nitrogen) against data from the UK, Germany and Peru, and run the model under simplified scenarios of primary succession and climate change. FUN is suitable for incorporation into a land surface scheme of a General Circulation Model and will be coupled with a soil model and dynamic global vegetation model as part of a land surface model (JULES).

Legislative measures for suppressing emission of nitrogen oxides from thermal power stations

Energy Technology Data Exchange (ETDEWEB)

Kotler, V.R.

1987-11-01

Reviews measures taken by some countries to control emission of nitrogen oxides from thermal power stations run on solid fuels, mazout and gas. Refers to maximum permissible concentrations of nitrogen oxides in USA (100 mg/m/sup 3/), Canada (460 mg/m/sup 3/), Japan (41-62 mg/m/sup 3/) and several European countries. Discusses legislative measures in FRG (Federal Regulations BImSchG), particularly Instruction No. 13 BImSchV concerning large boilers run on solid fuels or mazout (continuous monitoring of nitrogen oxide emission into atmosphere, equipping old boilers with means of reducing nitrogen oxide emission, reduction of acid rain). Gives maximum permissible concentrations of nitrogen oxides for new boilers agreed by various countries. 5 refs.

Flexible surface acoustic wave respiration sensor for monitoring obstructive sleep apnea syndrome

Science.gov (United States)

Jin, Hao; Tao, Xiang; Dong, Shurong; Qin, Yiheng; Yu, Liyang; Luo, Jikui; Deen, M. Jamal

2017-11-01

Obstructive sleep apnea syndrome (OSAS) has received much attention in recent years due to its significant harm to human health and high morbidity rate. A respiration monitoring system is needed to detect OSAS, so that the patient can receive treatment in a timely manner. Wired and wireless OSAS monitoring systems have been developed, but they require a wire connection and batteries to operate, and they are bulky, heavy and not user-friendly. In this paper, we propose the use of a flexible surface acoustic wave (SAW) microsensor to detect and monitor OSAS by measuring the humidity change associated with the respiration of a person. SAW sensors on rigid 128° YX LiNbO3 substrate are also characterized for this application. Results show both types of SAW sensors are suitable for OSAS monitoring with good sensitivity, repeatability and reliability, and the response time and recovery time for the flexible SAW sensors are 1.125 and 0.75 s, respectively. Our work demonstrates the potential for an innovative flexible microsensor for the detection and monitoring of OSAS.

Near-surface monitoring strategies for geologic carbon dioxide storage verification

Energy Technology Data Exchange (ETDEWEB)

Oldenburg, Curtis M.; Lewicki, Jennifer L.; Hepple, Robert P.

2003-10-31

Geologic carbon sequestration is the capture of anthropogenic carbon dioxide (CO{sub 2}) and its storage in deep geologic formations. Geologic CO{sub 2} storage verification will be needed to ensure that CO{sub 2} is not leaking from the intended storage formation and seeping out of the ground. Because the ultimate failure of geologic CO{sub 2} storage occurs when CO{sub 2} seeps out of the ground into the atmospheric surface layer, and because elevated concentrations of CO{sub 2} near the ground surface can cause health, safety, and environmental risks, monitoring will need to be carried out in the near-surface environment. The detection of a CO{sub 2} leakage or seepage signal (LOSS) in the near-surface environment is challenging because there are large natural variations in CO{sub 2} concentrations and fluxes arising from soil, plant, and subsurface processes. The term leakage refers to CO{sub 2} migration away from the intended storage site, while seepage is defined as CO{sub 2} passing from one medium to another, for example across the ground surface. The flow and transport of CO{sub 2} at high concentrations in the near-surface environment will be controlled by its high density, low viscosity, and high solubility in water relative to air. Numerical simulations of leakage and seepage show that CO{sub 2} concentrations can reach very high levels in the shallow subsurface even for relatively modest CO{sub 2} leakage fluxes. However, once CO{sub 2} seeps out of the ground into the atmospheric surface layer, surface winds are effective at dispersing CO{sub 2} seepage. In natural ecological systems with no CO{sub 2} LOSS, near-surface CO{sub 2} fluxes and concentrations are controlled by CO{sub 2} uptake by photosynthesis, and production by root respiration, organic carbon biodegradation in soil, deep outgassing of CO{sub 2}, and by exchange of CO{sub 2} with the atmosphere. Existing technologies available for monitoring CO{sub 2} in the near-surface environment

Nitrogen system for the SSC

International Nuclear Information System (INIS)

McAshan, M.; Thirumaleshwar, M.; Abramovich, S.; Ganni, V.

1992-10-01

The Superconducting Super Collider consists of two parallel magnet rings, each 87,120 m in circumference, constructed in a tunnel 25 m to 74 m below ground level. They are operated at a controlled low helium temperature in order to maintain the magnet windings in the superconducting state. To obtain this condition, the magnet cryostat is designed with a high-quality insulation obtained by a high vacuum chamber, multilayer insulation, and thermal shields at nominal temperatures of 84 K and 20 K. Thermal radiation and the conduction heat load through the supports are intercepted and absorbed by the 84-K shield. Liquid nitrogen provides the refrigeration for these loads. The 84-K shield is anchored to two 63.5-mm stainless-steel tubes. One of the tubes, the ''liquid line,'' serves as a conduit in the distribution system of liquid nitrogen. The other tube, the ''vapor line,'' is used to collect the nitrogen vapor generated in the cooling process and to supply this vapor to,the helium refrigerators for precooling. The vapor line may also be used as a continuous cooler by injecting controlled amounts of liquid nitrogen. The nitrogen system consists of nitrogen supplies; ten nitrogen dewars for the collider and two for the High Energy Booster located on the ground at the main shaft entrances; liquid and vapor transfer lines through the shaft to connect the surface and the tunnel systems; and transfer lines to bypass warm equipment sections of the collider. The nitrogen system is expected to operate at steady state condition except for cooldown, warmup, and system repair, for which transients are expected. During normal operation and standby modes of the collider, temperature, pressure, and mass flow are expected to be constant in all circuits of the nitrogen system. The conceptual design requirements for various flow schemes and the engineering considerations are presented in this report

XPS studies of nitrogen doping niobium used for accelerator applications

Science.gov (United States)

Yang, Ziqin; Lu, Xiangyang; Tan, Weiwei; Zhao, Jifei; Yang, Deyu; Yang, Yujia; He, Yuan; Zhou, Kui

2018-05-01

Nitrogen doping study on niobium (Nb) samples used for the fabrication of superconducting radio frequency (SRF) cavities was carried out. The samples' surface treatment was attempted to replicate that of the Nb SRF cavities, which includes heavy electropolishing (EP), nitrogen doping and the subsequent EP with different amounts of material removal. The surface chemical composition of Nb samples with different post treatments has been studied by XPS. The chemical composition of Nb, O, C and N was presented before and after Gas Cluster Ion Beam (GCIB) etching. No signals of poorly superconducting nitrides NbNx was found on the surface of any doped Nb sample with the 2/6 recipe before GCIB etching. However, in the depth range greater than 30 nm, the content of N element is below the XPS detection precision scope even for the Nb sample directly after nitrogen doping treatment with the 2/6 recipe.

Aerosols and surface UV products form Ozone Monitoring Instrument observations: An overview

NARCIS (Netherlands)

Torres, O.; Tanskanen, A.; Veihelmann, B.; Ahn, C.; Braak, R.; Bhartia, P.K.; Veefkind, J.P.; Levelt, P.F.

2007-01-01

We present an overview of the theoretical and algorithmic aspects of the Ozone Monitoring Instrument (OMI) aerosol and surface UV algorithms. Aerosol properties are derived from two independent algorithms. The nearUV algorithm makes use of OMI observations in the 350-390 nm spectral region to

Thermal behaviour of nitrogen implanted into zirconium

International Nuclear Information System (INIS)

Miyagawa, S.; Ikeyama, M.; Saitoh, K.; Nakao, S.; Niwa, H.; Tanemura, S.; Miyagawa, Y.

1994-01-01

Zirconium films were implanted with 15 N ions of energy 50keV to a total fluence of 1x10 18 ionscm -2 in an attempt to study the formation process and thermal stability of ZrN layers produced by high fluence implantation of nitrogen. Subsequent to the implantation at room temperature, samples were annealed at temperatures of 300 C-900 C. The depth profiles of the implanted nitrogen were measured by nuclear reaction analysis using the 15 N(p,αγ) 12 C at E R =429keV, and the surfaces were examined by thin film X-ray diffraction (XRD) and scanning electron microscopy. There were many blisters 0.2-0.4μm in diameter on the surface of the as-implanted samples and double peaks were observed in the nitrogen depth profiles; they were in both sides of the mean projected range. It was found that most of the blisters became extinct after annealing above 400 C, and the XRD peak (111) intensity was increased with the increase in the annealing temperature. Moreover, 14 N and 15 N implantations were superimposed on Zr samples in order to study the atomic migration of nitrogen at each stage of high fluence implantation. It was found that the decrease in the peak at the deeper layers was related to blister extinction and nitrogen diffusion into underling zirconium which could be correlated with radiation damage induced by post-implanted ions. ((orig.))

Quantitative monitoring of two simultaneously binding species using Label-Enhanced surface plasmon resonance.

Science.gov (United States)

Eng, Lars; Garcia, Brandon L; Geisbrecht, Brian V; Hanning, Anders

2018-02-26

Surface plasmon resonance (SPR) is a well-established method for biomolecular interaction studies. SPR monitors the binding of molecules to a solid surface, embodied as refractive index changes close to the surface. One limitation of conventional SPR is the universal nature of the detection that results in an inability to qualitatively discriminate between different binding species. Furthermore, it is impossible to directly discriminate two species simultaneously binding to different sites on a protein, which limits the utility of SPR, for example, in the study of allosteric binders or bi-specific molecules. It is also impossible in principle to discriminate protein conformation changes from actual binding events. Here we demonstrate how Label-Enhanced SPR can be utilized to discriminate and quantitatively monitor the simultaneous binding of two different species - one dye-labeled and one unlabeled - on a standard, single-wavelength SPR instrument. This new technique increases the versatility of SPR technology by opening up application areas where the usefulness of the approach has previously been limited. Copyright © 2018 Elsevier Inc. All rights reserved.

Differential Sensitivity of Nitrogen-Fixing, Azolla Microphylla to ...

African Journals Online (AJOL)

Michael Horsfall

photosynthesizing and nitrogen fixing micro-organisms contributing significantly ... Pesticide treatment with increasing doses accelerated the formation of reactive ... increased amount of proline in all the insecticide treated concentrations was .... monitoring the nitrite formation from ... centrifuged for 10 minutes in high speed.

Abrupt recent trend changes in atmospheric nitrogen dioxide over the Middle East

KAUST Repository

Lelieveld, J.

2015-08-21

Nitrogen oxides, released from fossil fuel use and other combustion processes, affect air quality and climate. From the mid-1990s onward, nitrogen dioxide (NO2) has been monitored from space, and since 2004 with relatively high spatial resolution by the Ozone Monitoring Instrument. Strong upward NO2 trends have been observed over South and East Asia and the Middle East, in particular over major cities. We show, however, that a combination of air quality control and political factors, including economical crisis and armed conflict, has drastically altered the emission landscape of nitrogen oxides in the Middle East. Large changes, including trend reversals, have occurred since about 2010 that could not have been predicted and therefore are at odds with emission scenarios used in projections of air pollution and climate change in the early 21st century.

The statistical evaluation and comparison of ADMS-Urban model for the prediction of nitrogen dioxide with air quality monitoring network.

Science.gov (United States)

Dėdelė, Audrius; Miškinytė, Auksė

2015-09-01

In many countries, road traffic is one of the main sources of air pollution associated with adverse effects on human health and environment. Nitrogen dioxide (NO2) is considered to be a measure of traffic-related air pollution, with concentrations tending to be higher near highways, along busy roads, and in the city centers, and the exceedances are mainly observed at measurement stations located close to traffic. In order to assess the air quality in the city and the air pollution impact on public health, air quality models are used. However, firstly, before the model can be used for these purposes, it is important to evaluate the accuracy of the dispersion modelling as one of the most widely used method. The monitoring and dispersion modelling are two components of air quality monitoring system (AQMS), in which statistical comparison was made in this research. The evaluation of the Atmospheric Dispersion Modelling System (ADMS-Urban) was made by comparing monthly modelled NO2 concentrations with the data of continuous air quality monitoring stations in Kaunas city. The statistical measures of model performance were calculated for annual and monthly concentrations of NO2 for each monitoring station site. The spatial analysis was made using geographic information systems (GIS). The calculation of statistical parameters indicated a good ADMS-Urban model performance for the prediction of NO2. The results of this study showed that the agreement of modelled values and observations was better for traffic monitoring stations compared to the background and residential stations.

Enhanced cytocompatibility of silver-containing biointerface by constructing nitrogen functionalities

Energy Technology Data Exchange (ETDEWEB)

Zhang, Wei, E-mail: weizhang@mail.ipc.ac.cn [Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Liu, Jun [Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Wang, Huaiyu [Department of Physics & Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China); Xu, Ying; Wang, Pingli [Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Ji, Junhui, E-mail: jhji@mail.ipc.ac.cn [Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Chu, Paul K. [Department of Physics & Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China)

2015-09-15

Graphical abstract: Constructing nitrogen functionalities is promising method to enhance cytocompatibility of the biointerface by simultaneous Ag and N{sub 2} plasma modification. - Highlights: • N{sub 2} plasma immersion ion implantation (PIII) treatment generates plenty of nitrogen functionalities on polymer substrate. • N{sub 2} PIII treatment increases surface roughness and hydrophilicity and improves its capability to adsorb protein. • Simultaneous Ag and N{sub 2} plasma modification constructs nitrogen functionalities to enhance cytocompatibility of the biointerface. - Abstract: Silver (Ag) has recently been introduced into polymeric biomedical implants by plasma immersion ion implantation (PIII) to enhance the antibacterial capability. However, Ag ions and nanoparticles can increase the cytotoxicity and inhibit cellular proliferation and the relationship is time- and dose-dependent. In this study, Ag and N{sub 2} PIII is conducted in concert to produce nitrogen functional groups as well as Ag-containing biointerface. In addition to the creation of nitrogen functionalities, the surface roughness and hydrophilicity are improved in favor of protein adsorption. Compared to the biointerface created by Ag PIII only, the nitrogen functionalities generated by N{sub 2} co-PIII do not affect DNA synthesis and the total protein level but evidently enhance cellular adhesion, viability, and proliferation at the biointerface. The modified surface is observed to upregulate the osteogenesis-related marker expression of bone cells in contact. Our findings suggest that dual Ag and N{sub 2} PIII is a desirable technique to enhance both the cytocompatibility and antibacterial capability of medical polymers.

Temperature effects on lithium-nitrogen reaction rates

International Nuclear Information System (INIS)

Ijams, W.J.; Kazimi, M.S.

1985-08-01

A series of experiments have been run with the aim of measuring the reaction rate of lithium and nitrogen over a wide spectrum of lithium pool temperatures. In these experiments, pure nitrogen was blown at a controlled flow rate over a preheated lithium pool. The pool had a surface area of approximately 4 cm 2 and a total volume of approximately 6 cm 3 . The system pressure varied from 0 to 4 psig. The reaction rate was very small - approximately 0.002 to 0.003 g Li min cm 2 for lithium temperatures below 500 0 C. Above 500 0 C the reaction rate began to increase sharply, and reached a maximum of approximately 0.80 g Li min cm 2 above 700 0 C. It dropped off beyond 1000 0 C and seemed to approach zero at 1150 0 C. The maximum reaction rate observed in these forced convection experiments was higher by 60% than those previously observed in experiments where the nitrogen flowed to the reaction site by means of natural convection. During a reaction, a hard nitride layer built up on the surface of the lithium pool - its effect on the reaction rate was observed. The effect of the nitrogen flow rate on the reaction rate was also observed

Satellite remote sensing for modeling and monitoring of water quality in the Great Lakes

Science.gov (United States)

Coffield, S. R.; Crosson, W. L.; Al-Hamdan, M. Z.; Barik, M. G.

2017-12-01

Consistent and accurate monitoring of the Great Lakes is critical for protecting the freshwater ecosystems, quantifying the impacts of climate change, understanding harmful algal blooms, and safeguarding public health for the millions who rely on the Lakes for drinking water. While ground-based monitoring is often hampered by limited sampling resolution, satellite data provide surface reflectance measurements at much more complete spatial and temporal scales. In this study, we implemented NASA data from the Moderate Resolution Imaging Spectroradiometer (MODIS) onboard the Aqua satellite to build robust water quality models. We developed and validated models for chlorophyll-a, nitrogen, phosphorus, and turbidity based on combinations of the six MODIS Ocean Color bands (412, 443, 488, 531, 547, and 667nm) for 2003-2016. Second, we applied these models to quantify trends in water quality through time and in relation to changing land cover, runoff, and climate for six selected coastal areas in Lakes Michigan and Erie. We found strongest models for chlorophyll-a in Lake Huron (R2 = 0.75), nitrogen in Lake Ontario (R2=0.66), phosphorus in Lake Erie (R2=0.60), and turbidity in Lake Erie (R2=0.86). These offer improvements over previous efforts to model chlorophyll-a while adding nitrogen, phosphorus, and turbidity. Mapped water quality parameters showed high spatial variability, with nitrogen concentrated largely in Superior and coastal Michigan and high turbidity, phosphorus, and chlorophyll near urban and agricultural areas of Erie. Temporal analysis also showed concurrence of high runoff or precipitation and nitrogen in Lake Michigan offshore of wetlands, suggesting that water quality in these areas is sensitive to changes in climate.

Improved OMI Nitrogen Dioxide Retrievals Aided by NASA's A-Train High-Resolution Data

Science.gov (United States)

Lamsal, L. N.; Krotkov, N. A.; Vasilkov, A. P.; Marchenko, S. V.; Qin, W.; Yang, E. S.; Fasnacht, Z.; Haffner, D. P.; Swartz, W. H.; Spurr, R. J. D.; Joiner, J.

2017-12-01

Space-based global observation of nitrogen dioxide (NO2) is among the main objectives of the NASA Aura Ozone Monitoring Instrument (OMI) mission, aimed at advancing our understanding of the sources and trends of nitrogen oxides (NOx). These applications benefit from improved retrieval techniques and enhancement in data quality. Here, we describe our recent and planned updates to the NASA OMI standard NO2 products. The products and documentation are publicly available from the NASA Goddard Earth Sciences Data and Information Services Center (https://disc.gsfc.nasa.gov/datasets/OMNO2_V003/summary/). The major changes include (1) improvements in spectral fitting algorithms for NO2 and cloud, (2) improved information in the vertical distribution of NO2, and (3) use of geometry-dependent surface reflectivity information derived from NASA's Aqua MODIS over land and the Cox-Munk slope distribution over ocean with a contribution from water-leaving radiance. These algorithm updates, which lead to more accurate tropospheric NO2 retrievals from OMI, are relevant for other past, contemporary, and future satellite instruments.

Surface Contamination Monitor and Survey Information Management System

Energy Technology Data Exchange (ETDEWEB)

NONE

1998-02-01

Shonka Research Associates, Inc.`s (SRA) Surface Contamination Monitor and Survey Information management System (SCM/SIMS) is designed to perform alpha and beta radiation surveys of floors and surfaces and document the measured data. The SRA-SCM/SIMS technology can be applied to routine operational surveys, characterization surveys, and free release and site closure surveys. Any large nuclear site can make use of this technology. This report describes a demonstration of the SRA-SCM/SIMS technology. This demonstration is part of the chicago Pile-5 (CP-5) Large-Scale Demonstration Project (LSDP) sponsored by the US Department of Energy (DOE), Office of Science and Technology (ST), Deactivation and Decommissioning Focus Area (DDFA). The objective of the LSDP is to select and demonstrate potentially beneficial technologies at the Argonne National Laboratory-East`s (ANL) CP-5 Research Reactor Facility. The purpose of the LSDP is to demonstrate that by using innovative and improved deactivation and decommissioning (D and D) technologies from various sources, significant benefits can be achieved when compared to baseline D and D technologies.

Surface Contamination Monitor and Survey Information Management System

International Nuclear Information System (INIS)

1998-02-01

Shonka Research Associates, Inc.'s (SRA) Surface Contamination Monitor and Survey Information management System (SCM/SIMS) is designed to perform alpha and beta radiation surveys of floors and surfaces and document the measured data. The SRA-SCM/SIMS technology can be applied to routine operational surveys, characterization surveys, and free release and site closure surveys. Any large nuclear site can make use of this technology. This report describes a demonstration of the SRA-SCM/SIMS technology. This demonstration is part of the chicago Pile-5 (CP-5) Large-Scale Demonstration Project (LSDP) sponsored by the US Department of Energy (DOE), Office of Science and Technology (ST), Deactivation and Decommissioning Focus Area (DDFA). The objective of the LSDP is to select and demonstrate potentially beneficial technologies at the Argonne National Laboratory-East's (ANL) CP-5 Research Reactor Facility. The purpose of the LSDP is to demonstrate that by using innovative and improved deactivation and decommissioning (D and D) technologies from various sources, significant benefits can be achieved when compared to baseline D and D technologies

Preferential incorporation of substitutional nitrogen near the atomic step edges in diluted nitride alloys

Energy Technology Data Exchange (ETDEWEB)

Cornet, C.; Nguyen Thanh, T.; Almosni, S.; Rohel, T.; Kuyyalil, J.; Rambaud, A.; Letoublon, A.; Bertru, N.; Durand, O.; Le Corre, A. [Universite Europeenne de Bretagne, INSA Rennes, France and CNRS, UMR 6082 Foton, 20 avenue des Buttes de Coeesmes, 35708 Rennes (France); Quinci, T. [Universite Europeenne de Bretagne, INSA Rennes, France and CNRS, UMR 6082 Foton, 20 avenue des Buttes de Coeesmes, 35708 Rennes (France); CEA LCP, INES, Savoie Technolac, 73375 Le Bourget du Lac (France)

2012-12-17

We have investigated the influence of the surface roughness on nitrogen incorporation during the molecular beam epitaxy of diluted nitrides, independently of the other growth parameters. GaPN/GaP layers grown simultaneously on surfaces displaying different roughnesses reveal a large difference in nitrogen incorporation despite the same growth temperature and growth rate. The same difference is found on quasi-lattice-matched GaAsPN demonstrating that the phenomenon is not related to any strain-induced mechanisms. The tendency is clearly confirmed when varying the growth conditions. As a direct consequence, the incorporation of substitutional nitrogen near the atomic step edges is found to be 6.7 times more probable than the in-plane nitrogen incorporation. The formation of N-N{sub i} clusters and their stability on the surface is discussed.

T-TY Tank Farm Interim Surface Barrier Demonstration - Vadose Zone Monitoring Plan

International Nuclear Information System (INIS)

Zhang, Z.F.; Strickland, Christopher E.; Field, Jim G.; Parker, Danny L.

2010-01-01

The Hanford Site has 149 underground single-shell tanks that store hazardous radioactive waste. Many of these tanks and their associated infrastructure (e.g., pipelines, diversion boxes) have leaked. Some of the leaked waste has entered the groundwater. The largest known leak occurred from the T-106 Tank of the 241-T Tank Farm in 1973. Five tanks are assumed to have leaked in the TY Farm. Many of the contaminants from those leaks still reside within the vadose zone within the T and TY Tank Farms. The Department of Energy's Office of River Protection seeks to minimize the movement of these contaminant plumes by placing interim barriers on the ground surface. Such barriers are expected to prevent infiltrating water from reaching the plumes and moving them further. The soil water regime is monitored to determine the effectiveness of the interim surface barriers. Soil-water content and water pressure are monitored using off-the-shelf equipment that can be installed by the hydraulic hammer technique. Four instrument nests were installed in the T Farm in fiscal year (FY) 2006 and FY2007; two nests were installed in the TY Farm in FY2010. Each instrument nest contains a neutron probe access tube, a capacitance probe, and four heat-dissipation units. A meteorological station has been installed at the north side of the fence of the T Farm. This document summarizes the monitoring methods, the instrument calibration and installation, and the vadose zone monitoring plan for interim barriers in T farm and TY Farm.

Catalysis by Design Using Surface Organometallic Nitrogen-Containing Fragments

KAUST Repository

Hamzaoui, Bilel

2016-06-14

The aim of this thesis is to explore the chemistry of well-defined silica-supported group 4 and group 5 complexes that contain one or more multiply-bonded nitrogen atoms. Such species have been recognized as crucial intermediates in many catalytic reactions (e.g. hydroaminoalkylation, olefin hydrogenation, imine metathesis…). The first chapter provided a bibliographic overview of the preparation and the reactivity of group 4 and 5 complexes towards hydroaminoalkylation and imine metathesis catalysis. The second chapter deals with the isolation and the characterization of a series of well-defined group 4 ƞ2-imine complexes surfaces species. 2D solid-state NMR (1H–13C HETCOR, Multiple Quantum) experiments have revealed consistently a unique structural rearrangement, viz azametallacycle occurring on the immobilized metal-amido ligands. Hydrogenolysis of the sole Zr-C bond in such species gives selectively a silica-supported zirconium monohydride that can perform the catalytic hydrogenation of olefins. The third chapter examines the mechanistic studies of the intermolecular hydroaminoalkylation using SOMC to identify the key metallacyclic surface intermediates (silica-supported three-membred and five-membered). The catalyst was regenerated by protonolysis and afforded pure amine. Catalytic testing of a selection of amine compounds with variable electronic properties was carried out. The fourth chapter deals with the generation and the characterization of well-defined silica-supported zirconium-imido complexes. The resulting species effectively catalyzes imine/imine cross-metathesis and thus considered as the first heterogeneous catalysts active for imine metathesis reaction. The fifth chapter studies the reaction of SBA15.1100 ºC with dry aniline and derivatives leading to opening strained siloxane bridges into acid-base paired functionalities (formation of N-phenylsilanamine-silanol pairs). This approach was successfully applied to the design of a series of

a Research on Monitoring Surface Deformation and Relationships with Surface Parameters in Qinghai Tibetan Plateau Permafrost

Science.gov (United States)

Mi, S. J.; Li, Y. T.; Wang, F.; Li, L.; Ge, Y.; Luo, L.; Zhang, C. L.; Chen, J. B.

2017-09-01

The Qinghai Tibetan Plateau permafrost has been the largest permafrost region in middle-low latitude in the world for its high altitude. For the large area permafrost, especially surface deformation brought by it, have serious influence on the road engineering, road maintaining and regional economic development. Consequently, it is essential to monitor the surface deformation and study factors that influent it. We monitored an area named Wudaoliang from July 25, 2015 to June 1, 2016 and 15 Sentinel images were obtained during this time. The area we chose is about 35 kilometers long and 2 kilometers wide, and the national road 109 of China passes through the area. The traditional PS-INSAR (Persistent Scatterer Interferometric Synthetic Aperture Radar) method is not suitable because less historical images in the research area and leading to the number of PS (Persistent Scatterer) points is not enough to obtain accurate deformation results. Therefore, in this paper, we used another method which named QUASI-PSInSAR (QUASI Persistent Scatterer Interferometric Synthetic Aperture Radar) to acquire deformation for it has the advantage to weaken or eliminate the effects of spatial and temporal correlation, which has proved by other scholar. After processing 15 images in the SARproz software, we got the conclusions that, 1) the biggest deformation velocity in the whole area was about 127.9mm/year and about 109.3 mm/year in the road; 2) apparent deformation which have surface deformation more than 30mm/year was about 1.7Km in the road. Meanwhile, soil moisture(SM), Land surface temperature (LST) and surface water(SW), which are primary parameters of the land surface over the same time were reversed by using Sentinel data, Landsat data and ZY-3 data, respectively. After analyzing SM, LST , SW and deformation, we obtained that wet areas which had bigger SM, lower LST and more SW, had greater percentage of severe deformation than arid areas; besides, deformation pattern were

Nitrogen removal and nitrous oxide emission in surface flow constructed wetlands for treating sewage treatment plant effluent: Effect of C/N ratios.

Science.gov (United States)

Li, Ming; Wu, Haiming; Zhang, Jian; Ngo, Huu Hao; Guo, Wenshan; Kong, Qiang

2017-09-01

In order to design treatment wetlands with maximal nitrogen removal and minimal nitrous oxide (N 2 O) emission, the effect of influent C/N ratios on nitrogen removal and N 2 O emission in surface flow constructed wetlands (SF CWs) for sewage treatment plant effluent treatment was investigated in this study. The results showed that nitrogen removal and N 2 O emission in CWs were significantly affected by C/N ratio of influent. Much higher removal efficiency of NH 4 + -N (98%) and TN (90%) was obtained simultaneously in SF CWs at C/N ratios of 12:1, and low N 2 O emission (8.2mg/m 2 /d) and the percentage of N 2 O-N emission in TN removal (1.44%) were also observed. These results obtained in this study would be utilized to determine how N 2 O fluxes respond to variations in C/N ratios and to improve the sustainability of CWs for wastewater treatment. Copyright © 2017 Elsevier Ltd. All rights reserved.

Evaluation of Agri-Environmental Measures in the Venice Lagoon Watershed. Nitrogen Budgets and Surplus Indicators

Directory of Open Access Journals (Sweden)

Marta Carpani

2008-09-01

Full Text Available One of the main concerns of the environmental scientists and policy makers is related to the environmental compatibility of current agricultural systems and, in particular, to the losses of chemical fertilizers and manure in surface and ground-waters, as a consequence of run-off and leaching phenomena. In most cases European recent agrienvironmental schemes envisaged specific measures for the reduction of fertilizer rates and the control of manure applications, in order to limit the releases of nutrients in surface and ground-waters. Substantial financial resources are invested in those measures and therefore the issue raises interest in monitoring and evaluating their effectiveness. Nutrient balance indicators are often used for quantitative assessment of the effectiveness of the measures in limiting the environmental impact of farming activities. N-surplus is one of the most commonly used indicators. The paper refers the results of a research project aimed at assessing the outcomes of agri-environmental measures implemented in the Venice Lagoon Watershed with an approach based upon the gross nitrogen balance, called “Nboxes”. The results of applying the Nboxes procedure to a sample of 550 farms set are presented, evidencing the expectations of greater effectiveness in terms of nitrogen surplus reduction from the measure C.5.1.3a and C.5.1.3b (low input farming and buffer strips. Measures supporting improved irrigation systems, controlled drainage and more rational livestock nutritional programmes and technologies, showed instead only limited potential for tangible contributions to the reduction of nitrogen surplus in cultivated soils.

Evaluation of Agri-Environmental Measures in the Venice Lagoon Watershed. Nitrogen Budgets and Surplus Indicators

Directory of Open Access Journals (Sweden)

Patrizia Trevisiol

2011-02-01

Full Text Available One of the main concerns of the environmental scientists and policy makers is related to the environmental compatibility of current agricultural systems and, in particular, to the losses of chemical fertilizers and manure in surface and ground-waters, as a consequence of run-off and leaching phenomena. In most cases European recent agrienvironmental schemes envisaged specific measures for the reduction of fertilizer rates and the control of manure applications, in order to limit the releases of nutrients in surface and ground-waters. Substantial financial resources are invested in those measures and therefore the issue raises interest in monitoring and evaluating their effectiveness. Nutrient balance indicators are often used for quantitative assessment of the effectiveness of the measures in limiting the environmental impact of farming activities. N-surplus is one of the most commonly used indicators. The paper refers the results of a research project aimed at assessing the outcomes of agri-environmental measures implemented in the Venice Lagoon Watershed with an approach based upon the gross nitrogen balance, called “Nboxes”. The results of applying the Nboxes procedure to a sample of 550 farms set are presented, evidencing the expectations of greater effectiveness in terms of nitrogen surplus reduction from the measure C.5.1.3a and C.5.1.3b (low input farming and buffer strips. Measures supporting improved irrigation systems, controlled drainage and more rational livestock nutritional programmes and technologies, showed instead only limited potential for tangible contributions to the reduction of nitrogen surplus in cultivated soils.

Microseismic Monitoring Using Sparse Surface Network of Broadband Instruments: Western Canada Shale Play Case Study

Science.gov (United States)

Yenier, E.; Baturan, D.; Karimi, S.

2016-12-01

Monitoring of seismicity related to oil and gas operations is routinely performed nowadays using a number of different surface and downhole seismic array configurations and technologies. Here, we provide a hydraulic fracture (HF) monitoring case study that compares the data set generated by a sparse local surface network of broadband seismometers to a data set generated by a single downhole geophone string. Our data was collected during a 5-day single-well HF operation, by a temporary surface network consisting of 10 stations deployed within 5 km of the production well. The downhole data was recorded by a 20 geophone string deployed in an observation well located 15 m from the production well. Surface network data processing included standard STA/LTA event triggering enhanced by template-matching subspace detection, grid search locations which was improved using the double-differencing re-location technique, as well as Richter (ML) and moment (Mw) magnitude computations for all detected events. In addition, moment tensors were computed from first motion polarities and amplitudes for the subset of highest SNR events. The resulting surface event catalog shows a very weak spatio-temporal correlation to HF operations with only 43% of recorded seismicity occurring during HF stages times. This along with source mechanisms shows that the surface-recorded seismicity delineates the activation of several pre-existing structures striking NNE-SSW and consistent with regional stress conditions as indicated by the orientation of SHmax. Comparison of the sparse-surface and single downhole string datasets allows us to perform a cost-benefit analysis of the two monitoring methods. Our findings show that although the downhole array recorded ten times as many events, the surface network provides a more coherent delineation of the underlying structure and more accurate magnitudes for larger magnitude events. We attribute this to the enhanced focal coverage provided by the surface

Dissolved organic nitrogen dynamics in the North Sea: A time series analysis (1995-2005)

NARCIS (Netherlands)

Van Engeland, T.; Soetaert, K.E.R.; Knuijt, A.; Laane, R.W.P.M.; Middelburg, J.J.

2010-01-01

Dissolved organic nitrogen (DON) dynamics in the North Sea was explored by means of long-term time series of nitrogen parameters from the Dutch national monitoring program. Generally, the data quality was good with little missing data points. Different imputation methods were used to verify the

Dynamic Mechanical Properties and Fracture Surface Morphologies of Core-Shell Rubber (CSR) Toughened Epoxy at Liquid Nitrogen (Ln2) Temperatures

Science.gov (United States)

Wang, J.; Magee, D.; Schneider, J. A.

2009-01-01

The dynamic mechanical properties and fracture surface morphologies were evaluated for a commercial epoxy resin toughened with two types of core-shell rubber (CSR) toughening agents (Kane Ace(Registered TradeMark) MX130 and MX960). The impact resistance (R) was evaluated by the resulting breaking energy measured in Charpy impact tests conducted on an instrumented drop tower. The resulting fracture surface morphologies were examined using Scanning Electron Microscopy (SEM). Fractographic observations of the CSR toughened epoxy tested at ambient temperature, showed a fracture as characterized by slender dendrite textures with large voids. The increasing number of dendrites and decreasing size of scale-like texture with more CSR particles corresponded with increased R. As the temperature decreased to Liquid Nitrogen (LN 2), the fracture surfaces showed a fracture characterized by a rough, torn texture containing many river markings and deep furrows.

Groundwater impacts on surface water quality and nutrient loads in lowland polder catchments: monitoring the greater Amsterdam area

Science.gov (United States)

Yu, Liang; Rozemeijer, Joachim; van Breukelen, Boris M.; Ouboter, Maarten; van der Vlugt, Corné; Broers, Hans Peter

2018-01-01

The Amsterdam area, a highly manipulated delta area formed by polders and reclaimed lakes, struggles with high nutrient levels in its surface water system. The polders receive spatially and temporally variable amounts of water and nutrients via surface runoff, groundwater seepage, sewer leakage, and via water inlets from upstream polders. Diffuse anthropogenic sources, such as manure and fertiliser use and atmospheric deposition, add to the water quality problems in the polders. The major nutrient sources and pathways have not yet been clarified due to the complex hydrological system in lowland catchments with both urban and agricultural areas. In this study, the spatial variability of the groundwater seepage impact was identified by exploiting the dense groundwater and surface water monitoring networks in Amsterdam and its surrounding polders. A total of 25 variables (concentrations of total nitrogen (TN), total phosphorus (TP), NH4, NO3, HCO3, SO4, Ca, and Cl in surface water and groundwater, N and P agricultural inputs, seepage rate, elevation, land-use, and soil type) for 144 polders were analysed statistically and interpreted in relation to sources, transport mechanisms, and pathways. The results imply that groundwater is a large source of nutrients in the greater Amsterdam mixed urban-agricultural catchments. The groundwater nutrient concentrations exceeded the surface water environmental quality standards (EQSs) in 93 % of the polders for TP and in 91 % for TN. Groundwater outflow into the polders thus adds to nutrient levels in the surface water. High correlations (R2 up to 0.88) between solutes in groundwater and surface water, together with the close similarities in their spatial patterns, confirmed the large impact of groundwater on surface water chemistry, especially in the polders that have high seepage rates. Our analysis indicates that the elevated nutrient and bicarbonate concentrations in the groundwater seepage originate from the decomposition of

Groundwater impacts on surface water quality and nutrient loads in lowland polder catchments: monitoring the greater Amsterdam area

Directory of Open Access Journals (Sweden)

L. Yu

2018-01-01

Full Text Available The Amsterdam area, a highly manipulated delta area formed by polders and reclaimed lakes, struggles with high nutrient levels in its surface water system. The polders receive spatially and temporally variable amounts of water and nutrients via surface runoff, groundwater seepage, sewer leakage, and via water inlets from upstream polders. Diffuse anthropogenic sources, such as manure and fertiliser use and atmospheric deposition, add to the water quality problems in the polders. The major nutrient sources and pathways have not yet been clarified due to the complex hydrological system in lowland catchments with both urban and agricultural areas. In this study, the spatial variability of the groundwater seepage impact was identified by exploiting the dense groundwater and surface water monitoring networks in Amsterdam and its surrounding polders. A total of 25 variables (concentrations of total nitrogen (TN, total phosphorus (TP, NH4, NO3, HCO3, SO4, Ca, and Cl in surface water and groundwater, N and P agricultural inputs, seepage rate, elevation, land-use, and soil type for 144 polders were analysed statistically and interpreted in relation to sources, transport mechanisms, and pathways. The results imply that groundwater is a large source of nutrients in the greater Amsterdam mixed urban–agricultural catchments. The groundwater nutrient concentrations exceeded the surface water environmental quality standards (EQSs in 93 % of the polders for TP and in 91 % for TN. Groundwater outflow into the polders thus adds to nutrient levels in the surface water. High correlations (R2 up to 0.88 between solutes in groundwater and surface water, together with the close similarities in their spatial patterns, confirmed the large impact of groundwater on surface water chemistry, especially in the polders that have high seepage rates. Our analysis indicates that the elevated nutrient and bicarbonate concentrations in the groundwater seepage originate

Tourism's nitrogen footprint on a Mesoamerican coral reef

Science.gov (United States)

Baker, D. M.; Rodríguez-Martínez, R. E.; Fogel, M. L.

2013-09-01

Globally, the eutrophication of coastal marine environments is a worsening problem that is accelerating the loss of biodiversity and ecosystem services. Coral reefs are among the most sensitive to this change, as chronic inputs of agricultural and wastewater effluents and atmospheric deposition disrupt their naturally oligotrophic state. Often, anthropogenic alteration of the coastal nitrogen pool can proceed undetected as rapid mixing with ocean waters can mask chronic and ephemeral nitrogen inputs. Monitoring nitrogen stable isotope values ( δ 15N) of benthic organisms provides a useful solution to this problem. Through a 7-yr monitoring effort in Quintana Roo, Mexico, we show that δ 15N values of the common sea fan Gorgonia ventalina were more variable near a developed (Akumal) site than at an undeveloped (Mahahual) site. Beginning in 2007, the global recession decreased tourist visitations to Akumal, which corresponded with a pronounced 1.6 ‰ decline in sea fan δ 15N through 2009, at which time δ 15N values were similar to those from Mahahual. With the recovery of tourism, δ 15N values increased to previous levels. Overall, 84 % of the observed variation in δ 15N was explained by tourist visitations in the preceding year alone, indicating that variable nitrogen source contributions are correlated with sea fan δ 15N values. We also found that annual precipitation accounted for some variation in δ 15N, likely due to its role in groundwater flushing into the sea. Together, these factors accounted for 96 % of the variation in δ 15N. Using a mixing model, we estimate that sewage can account for up to 42 % of nitrogen in sea fan biomass. These findings illustrate the high connectivity between land-based activities and coral reef productivity and the measurable impact of the tourism industry on the ecosystem it relies on.

Replaceable liquid nitrogen piping

International Nuclear Information System (INIS)

Yasujima, Yasuo; Sato, Kiyoshi; Sato, Masataka; Hongo, Toshio

1982-01-01

This liquid nitrogen piping with total length of about 50 m was made and installed to supply the liquid nitrogen for heat insulating shield to three superconducting magnets for deflection and large super-conducting magnet for detection in the π-meson beam line used for high energy physics experiment in the National Laboratory for High Energy Physics. The points considered in the design and manufacture stages are reported. In order to minimize the consumption of liquid nitrogen during transport, vacuum heat insulation method was adopted. The construction period and cost were reduced by the standardization of the components, the improvement of welding works and the elimination of ineffective works. For simplifying the maintenance, spare parts are always prepared. The construction and the procedure of assembling of the liquid nitrogen piping are described. The piping is of double-walled construction, and its low temperature part was made of SUS 316L. The super-insulation by aluminum vacuum evaporation and active carbon were attached on the external surface of the internal pipe. The final leak test and the heating degassing were performed. The tests on evacuation, transport capacity and heat entry are reported. By making the internal pipe into smaller size, the piping may be more efficient. (Kako, I.)

Forests, nitrogen and albedo, a very interesting trio indeed

Directory of Open Access Journals (Sweden)

Borghetti M

2009-01-01

Full Text Available A short comment is made on a recent paper (Ollinger et al. 2008 which shows that forest ecosystem carbon uptake in temperate and boreal forests is directly related to canopy nitrogen concentration and that both carbon uptake capacity and canopy nitrogen concentration are positively correlated with shortwave surface albedo measured with broad-band satellite sensors.

Evaluation of Six Algorithms to Monitor Wheat Leaf Nitrogen Concentration

Directory of Open Access Journals (Sweden)

Xia Yao

2015-11-01

Full Text Available The rapid and non-destructive monitoring of the canopy leaf nitrogen concentration (LNC in crops is important for precise nitrogen (N management. Nowadays, there is an urgent need to identify next-generation bio-physical variable retrieval algorithms that can be incorporated into an operational processing chain for hyperspectral satellite missions. We assessed six retrieval algorithms for estimating LNC from canopy reflectance of winter wheat in eight field experiments. These experiments represented variations in the N application rates, planting densities, ecological sites and cultivars and yielded a total of 821 samples from various places in Jiangsu, China over nine consecutive years. Based on the reflectance spectra and their first derivatives, six methods using different numbers of wavelengths were applied to construct predictive models for estimating wheat LNC, including continuum removal (CR, vegetation indices (VIs, stepwise multiple linear regression (SMLR, partial least squares regression (PLSR, artificial neural networks (ANNs, and support vector machines (SVMs. To assess the performance of these six methods, we provided a systematic evaluation of the estimation accuracies using the six metrics that were the coefficients of determination for the calibration (R2C and validation (R2V sets, the root mean square errors of prediction (RMSEP for the calibration and validation sets, the ratio of prediction to deviation (RPD, the computational efficiency (CE and the complexity level (CL. The following results were obtained: (1 For the VIs method, SAVI(R1200, R705 produced a more accurate estimation of the LNC than other indices, with R²C, R²V, RMSEP, RPD and CE values of 0.844, 0.795, 0.384, 2.005 and 0.10 min, respectively; (2 For the SMLR, PLSR, ANNs and SVMs methods, the SVMs using the first derivative canopy spectra (SVM-FDS offered the best accuracy in terms of R²C, R²V, RMSEP, RPD, and CE, at 0.96, 0.78, 0.37, 2.02, and 21

Modification of surface layers of copper under the action of the volumetric discharge initiated by an avalanche electron beam in nitrogen and CO2 at atmospheric pressure

Science.gov (United States)

Shulepov, M. A.; Akhmadeev, Yu. Kh.; Tarasenko, V. F.; Kolubaeva, Yu. A.; Krysina, O. V.; Kostyrya, I. D.

2011-05-01

The results of experimental investigations of the action of the volumetric discharge initiated by an avalanche electron beam on the surface of copper specimens are presented. The volumetric (diffuse) discharge in nitrogen and CO2 at atmospheric pressure was initiated by applying high voltage pulses of nanosecond duration to a tubular foil cathode. It has been found that the treatment of a copper surface by this type of discharge increases the hardness of the surface layer due to oxidation.

Surface modification by nitrogen plasma immersion ion implantation into new steel 460Li–21Cr in a capacitively coupled radio frequency discharge

International Nuclear Information System (INIS)

Bhuyan, H.; Mändl, S.; Bora, B.; Favre, M.; Wyndham, E.; Maze, J.R.; Walczak, M.; Manova, D.

2014-01-01

Highlights: • Nitriding of a novel steel has been done in a RF plasma by PIII technique. • Improved hardness and wear behavior have been observed. • Hardness was improved by a factor 4 and the wear by 2 orders of magnitude. • Fast, anomalous diffusion, similar to nitrogen in expanded austenite is observed. - Abstract: A novel steel 460Li–21Cr belonging to a new generation of superferritic grade steel has been implanted with nitrogen in a low power 13.56 MHz radio frequency plasma by the plasma immersion ion implantation (PIII) technique in order to study its physical and chemical properties under different experimental conditions. We observed improved hardness and wear behavior of 460Li–21Cr steel with a layer thickness between 1.5 and 4.0 μm after 60 min implantation in the temperature range from 350 to 550 °C. The modified surface layer containing nitrogen does not show CrN in X-ray diffraction (XRD). Compared to untreated substrates, the hardness can be increased by a factor of 4, depending on the experimental conditions, and the wear behavior was also improved by two orders of magnitude. The results are very similar to those for austenitic stainless steel with a similar pronounced increase in wear resistance and plateau-like nitrogen depth profiles

Cryodeposition of nitrogen gas on a surface cooled by helium II

International Nuclear Information System (INIS)

Dhuley, R. C.; Bosque, E. S.; Van Sciver, S. W.

2014-01-01

Catastrophic loss of beam tube vacuum in a superconducting particle accelerator can be simulated by sudden venting of a long high vacuum channel cooled on its outer surface by He II. The rapid rush of atmospheric air in such an event shows an interesting propagation effect, which is much slower than the shock wave that occurs with vacuum loss at ambient conditions. This is due to flash frosting/deposition of air on the cold walls of the channel. Hence to characterize the propagation as well as the associated heat transfer, it is first necessary to understand the deposition process. Here we attempt to model the growth of nitrogen frost layer on a cold plate in order to estimate its thickness with time. The deposition process can be divided into two regimes- free molecular and continuum. It is shown that in free molecular regime, the frost growth can be modeled reasonably well using cryopump theory and general heat transfer relations. The continuum regime is more complex to model, given the higher rate of gas incident on cryosurface causing a large heat load on helium bath and changing cryosurface temperature. Results from the continuum regime are discussed in the context of recent experiments performed in our laboratory

Cryodeposition of nitrogen gas on a surface cooled by helium II

Energy Technology Data Exchange (ETDEWEB)

Dhuley, R. C.; Bosque, E. S.; Van Sciver, S. W. [Cryogenics Group, National High Magnetic Field Laboratory, Tallahassee, FL 32310 USA and Mechanical Engineering Department, FAMU-FSU College of Engineering, Tallahassee, FL 32310 (United States)

2014-01-29

Catastrophic loss of beam tube vacuum in a superconducting particle accelerator can be simulated by sudden venting of a long high vacuum channel cooled on its outer surface by He II. The rapid rush of atmospheric air in such an event shows an interesting propagation effect, which is much slower than the shock wave that occurs with vacuum loss at ambient conditions. This is due to flash frosting/deposition of air on the cold walls of the channel. Hence to characterize the propagation as well as the associated heat transfer, it is first necessary to understand the deposition process. Here we attempt to model the growth of nitrogen frost layer on a cold plate in order to estimate its thickness with time. The deposition process can be divided into two regimes- free molecular and continuum. It is shown that in free molecular regime, the frost growth can be modeled reasonably well using cryopump theory and general heat transfer relations. The continuum regime is more complex to model, given the higher rate of gas incident on cryosurface causing a large heat load on helium bath and changing cryosurface temperature. Results from the continuum regime are discussed in the context of recent experiments performed in our laboratory.

Instrumentation for Air Pollution Monitoring

Science.gov (United States)

Hollowell, Craig D.; McLaughlin, Ralph D.

1973-01-01

Describes the techniques which form the basis of current commercial instrumentation for monitoring five major gaseous atmospheric pollutants (sulfur dioxide, oxides of nitrogen, oxidants, carbon monoxide, and hydrocarbons). (JR)

Incorporating nitrogen fixing cyanobacteria in the global biogeochemical model HAMOCC

Science.gov (United States)

Paulsen, Hanna; Ilyina, Tatiana; Six, Katharina

2015-04-01

Nitrogen fixation by marine diazotrophs plays a fundamental role in the oceanic nitrogen and carbon cycle as it provides a major source of 'new' nitrogen to the euphotic zone that supports biological carbon export and sequestration. Since most global biogeochemical models include nitrogen fixation only diagnostically, they are not able to capture its spatial pattern sufficiently. Here we present the incorporation of an explicit, dynamic representation of diazotrophic cyanobacteria and the corresponding nitrogen fixation in the global ocean biogeochemical model HAMOCC (Hamburg Ocean Carbon Cycle model), which is part of the Max Planck Institute for Meteorology Earth system model (MPI-ESM). The parameterization of the diazotrophic growth is thereby based on available knowledge about the cyanobacterium Trichodesmium spp., which is considered as the most significant pelagic nitrogen fixer. Evaluation against observations shows that the model successfully reproduces the main spatial distribution of cyanobacteria and nitrogen fixation, covering large parts of the tropical and subtropical oceans. Besides the role of cyanobacteria in marine biogeochemical cycles, their capacity to form extensive surface blooms induces a number of bio-physical feedback mechanisms in the Earth system. The processes driving these interactions, which are related to the alteration of heat absorption, surface albedo and momentum input by wind, are incorporated in the biogeochemical and physical model of the MPI-ESM in order to investigate their impacts on a global scale. First preliminary results will be shown.

Nitrogen Recovery by Fe-Ti Alloy from Molten Lithium at High Temperatures

International Nuclear Information System (INIS)

Juro Yagi; Akihiro Suzuki; Takayuki Terai; Takeo Muroga

2006-01-01

Molten lithium will be used as a beam target of IFMIF (International Fusion Materials Irradiation Facility), and is also expected as a self-cooling and tritium breeding material in fusion reactors. Since tritium is generated in both cases, tritium recovery is required from viewpoints of safety and a feasible fuel cycle. Nitrogen impurity in the lithium, however, not only enhance corrosion to tubing materials, but also promote nitride contamination on a surface of yttrium, which is considered to be a tritium gettering candidate. In our previous study, nitrogen recovery by hot trap method with Fe + 5%Ti alloy as a gettering material showed a higher nitrogen reduction capacity than that with Ti or Cr metal. In this study, high temperature recovery of nitrogen with Fe-Ti alloy was examined to achieve more efficient recovery and higher recovery rate coefficient. Fe - 4%Ti alloy are fabricated by electron beam melting, and its thin plates (40 mm x 10 mm x 1 mm) are used in our experiments. The Fe - 4%Ti alloy plates were immersed into 25 g of liquid lithium in Mo crucible under Ar atmosphere. The crucible was put in a SUS316 stainless steel pot heated at 600, 700, or 800 o C up to 100 hours. A small portion of the liquid lithium in the crucible was sampled out with adequate time interval, and the nitrogen concentrations in the sampled lithium were observed by changing nitrogen to ammonia. Experiments using lithium containing about 100 wt. ppm of nitrogen at the beginning show that the nitrogen reduction became faster with temperature and the minimum achieved nitrogen concentration was less than 20 wppm in case of 800 C. SEM-EDS analysis on the plates after experiment shows a Ti-rich surface layer of tens of micrometers on the alloy immersed in lithium at 800 C, and XPS analysis indicates the surface layer is TiN, while no Ti-rich layer nor TiN were observed on the alloys immersed at 600 o C and 700 o C. By increasing temperature from 600 o C to 800 o C, the diffusion

Prediction of traffic-related nitrogen oxides concentrations using Structural Time-Series models

Science.gov (United States)

Lawson, Anneka Ruth; Ghosh, Bidisha; Broderick, Brian

2011-09-01

Ambient air quality monitoring, modeling and compliance to the standards set by European Union (EU) directives and World Health Organization (WHO) guidelines are required to ensure the protection of human and environmental health. Congested urban areas are most susceptible to traffic-related air pollution which is the most problematic source of air pollution in Ireland. Long-term continuous real-time monitoring of ambient air quality at such urban centers is essential but often not realistic due to financial and operational constraints. Hence, the development of a resource-conservative ambient air quality monitoring technique is essential to ensure compliance with the threshold values set by the standards. As an intelligent and advanced statistical methodology, a Structural Time Series (STS) based approach has been introduced in this paper to develop a parsimonious and computationally simple air quality model. In STS methodology, the different components of a time-series dataset such as the trend, seasonal, cyclical and calendar variations can be modeled separately. To test the effectiveness of the proposed modeling strategy, average hourly concentrations of nitrogen dioxide and nitrogen oxides from a congested urban arterial in Dublin city center were modeled using STS methodology. The prediction error estimates from the developed air quality model indicate that the STS model can be a useful tool in predicting nitrogen dioxide and nitrogen oxides concentrations in urban areas and will be particularly useful in situations where the information on external variables such as meteorology or traffic volume is not available.

On the feasibility of borehole-to-surface electromagnetics for monitoring CO2 sequestration

Science.gov (United States)

Wilson, G. A.; Zhdanov, M. S.; Hibbs, A. D.; Black, N.; Gribenko, A. V.; Cuma, M.; Agundes, A.; Eiskamp, G.

2012-12-01

Carbon capture and storage (CCS) projects rely on storing supercritical CO2 in deep saline reservoirs where buoyancy forces drive the injected CO2 upward into the aquifer until a seal is reached. The permanence of the sequestration depends entirely on the long-term geological integrity of the seal. Active geophysical monitoring of the sequestration is critical for informing CO2 monitoring, accounting and verification (MVA) decisions. During injection, there exists a correlation between the changes in CO2 and water saturations in a saline reservoir. Dissolved salts react with the CO2 to precipitate out as carbonates, thereby generally decreasing the electrical resistivity. As a result, there is a correlation between the change in fluid saturation and measured electromagnetic (EM) fields. The challenge is to design an EM survey appropriate for monitoring large, deep reservoirs. Borehole-to-surface electromagnetic (BSEM) surveys consist of borehole-deployed galvanic transmitters and a surface-based array of electric and magnetic field sensors. During a recent field trial, it was demonstrated that BSEM could successfully identify the oil-water contact in the water-injection zone of a carbonate reservoir. We review the BSEM methodology, and perform full-field BSEM modeling. The 3D resistivity models used in this study are based on dynamic reservoir simulations of CO2 injection into a saline reservoir. Although the electric field response at the earth's surface is low, we demonstrate that it can be accurately measured and processed with novel methods of noise cancellation and sufficient stacking over the period of monitoring to increase the signal-to-noise ratio for subsequent seismic- and well-constrained 3D inversion. For long-term or permanent monitoring, we discuss the deployment of novel electric field sensors with chemically inert electrodes that couple to earth in a capacitive manner. This capacitive coupling is a purely EM phenomenon, which, to first order, has

Abiotic nitrogen fixation on terrestrial planets: reduction of NO to ammonia by FeS.

Science.gov (United States)

Summers, David P; Basa, Ranor C B; Khare, Bishun; Rodoni, David

2012-02-01

Understanding the abiotic fixation of nitrogen and how such fixation can be a supply of prebiotic nitrogen is critical for understanding both the planetary evolution of, and the potential origin of life on, terrestrial planets. As nitrogen is a biochemically essential element, sources of biochemically accessible nitrogen, especially reduced nitrogen, are critical to prebiotic chemistry and the origin of life. Loss of atmospheric nitrogen can result in loss of the ability to sustain liquid water on a planetary surface, which would impact planetary habitability and hydrological processes that shape the surface. It is known that NO can be photochemically converted through a chain of reactions to form nitrate and nitrite, which can be subsequently reduced to ammonia. Here, we show that NO can also be directly reduced, by FeS, to ammonia. In addition to removing nitrogen from the atmosphere, this reaction is particularly important as a source of reduced nitrogen on an early terrestrial planet. By converting NO directly to ammonia in a single step, ammonia is formed with a higher product yield (~50%) than would be possible through the formation of nitrate/nitrite and subsequent conversion to ammonia. In conjunction with the reduction of NO, there is also a catalytic disproportionation at the mineral surface that converts NO to NO₂ and N₂O. The NO₂ is then converted to ammonia, while the N₂O is released back in the gas phase, which provides an abiotic source of nitrous oxide.

[Dynamic changes in functional genes for nitrogen bioremediation of petroleum-contaminated soil cycle during].

Science.gov (United States)

Wu, Bin-Bin; Lu, Dian-Nan; Liu, Zheng

2012-06-01

Microorganisms in nitrogen cycle serve as an important part of the ecological function of soil. The aim of this research was to monitor the abundance of nitrogen-fixing, denitrifying and nitrifying bacteria during bioaugmentation of petroleum-contaminated soil using real-time polymerase chain reaction (real-time PCR) of nifH, narG and amoA genes which encode the key enzymes in nitrogen fixation, nitrification and ammoniation respectively. Three different kinds of soils, which are petroleum-contaminated soil, normal soil, and remediated soil, were monitored. It was shown that the amounts of functional microorganisms in petroleum-contaminated soil were far less than those in normal soil, while the amounts in remediated soil and normal soil were comparable. Results of this experiment demonstrate that nitrogen circular functional bacteria are inhibited in petroleum-contaminated soil and can be recovered through bioremediation. Furthermore, copies of the three functional genes as well as total petroleum hydrocarbons (TPH) for soils with six different treatments were monitored. Among all treatments, the one, into which both E. cloacae as an inoculant and wheat straw as an additive were added, obtained the maximum copies of 2.68 x 10(6), 1.71 x 10(6) and 8.54 x 10(4) per gram dry soil for nifH, narG and amoA genes respectively, companying with the highest degradation rate (48% in 40 days) of TPH. The recovery of functional genes and removal of TPH were better in soil inoculated with E cloacae and C echinulata collectively than soil inoculated with E cloacae only. All above results suggest that the nitrogen circular functional genes could be applied to monitor and assess the bioremediation of petroleum-contaminated soil.

Accounting for Natural Reduction of Nitrogen

DEFF Research Database (Denmark)

Højberg, A L; Refsgaard, J. C.; Hansen, A.L.

the same restriction for all areas independent on drainage schemes, hydrogeochemical conditions in the subsurface and retention in surface waters. Although significant reductions have been achieved this way, general measures are not cost-effective, as nitrogen retention (primarily as denitrification...

40 CFR 98.164 - Monitoring and QA/QC requirements.

Science.gov (United States)

2010-07-01

... Methods for Instrumental Determination of Carbon, Hydrogen, and Nitrogen in Petroleum Products and... Determination of Carbon, Hydrogen, and Nitrogen in Laboratory Samples of Coal (incorporated by reference, see... (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Hydrogen Production § 98.164 Monitoring and QA/QC requirements...

Helicopter-based lidar system for monitoring the upper ocean and terrain surface

International Nuclear Information System (INIS)

Lee, Kwi Joo; Park, Youngsik; Bunkin, Alexey; Pershin, Serguei; Voliak, Konstantin; Nunes, Raul

2002-01-01

A compact helicopter-based lidar system is developed and tested under laboratory and field conditions. It is shown that the lidar can measure concentrations of chlorophyll a and dissolved organic matter at the surface of water bodies, detect fluorescence spectra of ground vegetation at a distance of up to 530 m, and determine the vertical profile of light-scattering particle concentration in the upper ocean. The possibilities of the lidar system are demonstrated by detection of polluted areas at the ocean surface, by online monitoring of three-dimensional distribution of light-scattering layers, and by recognition of plant types and physiological states

Monitoring of Surface Subsidence of the Mining Area Based on Sbas

Science.gov (United States)

Zhu, Y.; Zhou, S.; Zang, D.; Lu, T.

2018-05-01

This paper has collected 7 scenes of L band PALSAR sensor radar data of a mine in FengCheng city, jiangxi province, using the Small-baseline Subset (SBAS) method to invert the surface subsidence of the mine. Baselines of interference less than 800m has been chosen to constitute short baseline differential interference atlas, using pixels whose average coherent coefficient was larger than or equal to 0.3 as like high coherent point target, using singular value decomposition (SVD) method to calculate deformation phase sequence based on these high coherent points, and the accumulation of settlements of study area of different period had been obtained, so as to reflect the ground surface settlement evolution of the settlement of the area. The results of the study has showed that: SBAS technology has overcome coherent problem of the traditionality D-InSAR technique, continuous deformation field of surface mining in time dimension of time could been obtained, characteristics of ground surface settlement of mining subsidence in different period has been displayed, so to improve the accuracy and reliability of the monitoring results.

Nitrogen-fixing bacteria in Mediterranean seagrass (Posidonia oceanica) roots

KAUST Repository

Garcias Bonet, Neus

2016-03-09

Biological nitrogen fixation by diazotrophic bacteria in seagrass rhizosphere and leaf epiphytic community is an important source of nitrogen required for plant growth. However, the presence of endophytic diazotrophs remains unclear in seagrass tissues. Here, we assess the presence, diversity and taxonomy of nitrogen-fixing bacteria within surface-sterilized roots of Posidonia oceanica. Moreover, we analyze the nitrogen isotopic signature of seagrass tissues in order to notice atmospheric nitrogen fixation. We detected nitrogen-fixing bacteria by nifH gene amplification in 13 out of the 78 roots sampled, corresponding to 9 locations out of 26 meadows. We detected two different types of bacterial nifH sequences associated with P. oceanica roots, which were closely related to sequences previously isolated from the rhizosphere of a salt marsh cord grass and a putative anaerobe. Nitrogen content of seagrass tissues showed low isotopic signatures in all the sampled meadows, pointing out the atmospheric origin of the assimilated nitrogen by seagrasses. However, this was not related with the presence of endophytic nitrogen fixers, suggesting the nitrogen fixation occurring in rhizosphere and in the epiphytic community could be an important source of nitrogen for P. oceanica. The low diversity of nitrogen-fixing bacteria reported here suggests species-specific relationships between diazotrophs and P. oceanica, revealing possible symbiotic interactions that could play a major role in nitrogen acquisition by seagrasses in oligotrophic environments where they form lush meadows.

Particle beam experiments for the analysis of reactive sputtering processes in metals and polymer surfaces

Energy Technology Data Exchange (ETDEWEB)

Corbella, Carles; Grosse-Kreul, Simon; Kreiter, Oliver; Arcos, Teresa de los; Benedikt, Jan; Keudell, Achim von [RD Plasmas with Complex Interactions, Ruhr-Universität Bochum, Universitätsstr. 150, 44780 Bochum (Germany)

2013-10-15

A beam experiment is presented to study heterogeneous reactions relevant to plasma-surface interactions in reactive sputtering applications. Atom and ion sources are focused onto the sample to expose it to quantified beams of oxygen, nitrogen, hydrogen, noble gas ions, and metal vapor. The heterogeneous surface processes are monitored in situ by means of a quartz crystal microbalance and Fourier transform infrared spectroscopy. Two examples illustrate the capabilities of the particle beam setup: oxidation and nitriding of aluminum as a model of target poisoning during reactive magnetron sputtering, and plasma pre-treatment of polymers (PET, PP)

21 CFR 862.1515 - Nitrogen (amino-nitrogen) test system.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Nitrogen (amino-nitrogen) test system. 862.1515... Systems § 862.1515 Nitrogen (amino-nitrogen) test system. (a) Identification. A nitrogen (amino-nitrogen) test system is a device intended to measure amino acid nitrogen levels in serum, plasma, and urine...

Improved Electrochemical Performance of Biomass-Derived Nanoporous Carbon/Sulfur Composites Cathode for Lithium-Sulfur Batteries by Nitrogen Doping

International Nuclear Information System (INIS)

Geng, Zhen; Xiao, Qiangfeng; Wang, Dabin; Yi, Guanghai; Xu, Zhigang; Li, Bing; Zhang, Cunman

2016-01-01

A two-step method with high-efficiency is developed to prepare nitrogen doped activated carbons (NACs) with high surface area and nitrogen content. Based on the method, series of NACs with similar surface area and pore texture but different nitrogen content and nitrogen group species are successfully prepared. The influence of nitrogen doping on electrochemical performance of carbon/sulfur composites cathode is studied deeply under the conditions of similar surface area and pore texture. It presents the directly experimental demonstration that both nitrogen content and nitrogen group species play crucial roles on electrochemical performance of carbon/sulfur composites cathode. NAC/sulfur composites show the much improved cycling performance, which is about 3.5 times as that of nitrogen free carbon. Improved electrochemical performance is due to synergistic effects between nitrogen content and effective nitrogen groups, which enables effective trapping of lithium polysulfides within carbon framework. Besides, it is found that oxygen groups exist in carbon materials obviously influence electrochemical performance of cathode, which could be ignored in most of studies. Based on above, it can be concluded that enhanced chemisorption to lithium polysulfides by functional groups modification is the effective route to improve the electrochemical performance of Li-S battery.

77 FR 64244 - Revision to Ambient Nitrogen Dioxide Monitoring Requirements

Science.gov (United States)

2012-10-19

... characterization of NO 2 exposure for susceptible and vulnerable populations.\\3\\ The EPA Regional Administrators... demands of funding other new and expanded monitoring networks, including the source and population lead... NO 2 monitors which are the second near-road NO 2 monitor in any CBSA with a population of 2,500,000...

Assessment and Monitoring of Nutrient Management in Irrigated Agriculture for Groundwater Quality Protection

Science.gov (United States)

Harter, T.; Davis, R.; Smart, D. R.; Brown, P. H.; Dzurella, K.; Bell, A.; Kourakos, G.

2017-12-01

Nutrient fluxes to groundwater have been subject to regulatory assessment and control only in a limited number of countries, including those in the European Union, where the Water Framework Directive requires member countries to manage groundwater basis toward achieving "good status", and California, where irrigated lands will be subject to permitting, stringent nutrient monitoring requirements, and development of practices that are protective of groundwater. However, research activities to rigorously assess agricultural practices for their impact on groundwater have been limited and instead focused on surface water protection. For groundwater-related assessment of agricultural practices, a wide range of modeling tools has been employed: vulnerability studies, nitrogen mass balance assessments, crop-soil-system models, and various statistical tools. These tools are predominantly used to identify high risk regions, practices, or crops. Here we present the development of a field site for rigorous in-situ evaluation of water and nutrient management practices in an irrigated agricultural setting. Integrating groundwater monitoring into agricultural practice assessment requires large research plots (on the order of 10s to 100s of hectares) and multi-year research time-frames - much larger than typical agricultural field research plots. Almonds are among the most common crops in California with intensive use of nitrogen fertilizer and were selected for their high water quality improvement potential. Availability of an orchard site with relatively vulnerable groundwater conditions (sandy soils, water table depth less than 10 m) was also important in site selection. Initial results show that shallow groundwater concentrations are commensurate with nitrogen leaching estimates obtained by considering historical, long-term field nitrogen mass balance and groundwater dynamics.

Uptake of fertilizer nitrogen and soil nitrogen by rice using 15N-labelled nitrogen fertilizer

International Nuclear Information System (INIS)

Reddy, K.R.; Patrick, W.H. Jr.

1980-01-01

Data from five field experiments using labelled nitrogen fertilizer were used to determine the relative effects of soil nitrogen and fertilizer nitrogen on rice yield. Yield of grain was closely correlated with total aboveground nitrogen uptake (soil + fertilizer), less closely correlated with soil nitrogen uptake and not significantly correlated with fertilizer nitrogen uptake. When yield increase rather than yield was correlated with fertilizer nitrogen uptake, the correlation coefficient was statistically significant. (orig.)

T Tank Farm Interim Surface Barrier Demonstration--Vadose Zone Monitoring Plan

International Nuclear Information System (INIS)

Zhang, Z. F.; Keller, Jason M.; Strickland, Christopher E.

2007-01-01

The Hanford Site has 149 underground single-shell tanks that store hazardous radioactive waste. Many of these tanks and their associated infrastructure (e.g., pipelines, diversion boxes) have leaked. Some of the leaked waste has entered the groundwater. The largest known leak occurred from the T-106 Tank in 1973. Many of the contaminants from that leak still reside within the vadose zone beneath the T Tank Farm. CH2M Hill Hanford Group, Inc. seeks to minimize movement of this residual contaminant plume by placing an interim barrier on the surface. Such a barrier is expected to prevent infiltrating water from reaching the plume and moving it further. A plan has been prepared to monitor and determine the effectiveness of the interim surface barrier. Soil water content and water pressure will be monitored using off-the-shelf equipment that can be installed by the hydraulic hammer technique. In fiscal year 2006, two instrument nests were installed. Each instrument nest contains a neutron probe access tube, a capacitance probe, four heat-dissipation units, and a drain gauge to measure soil water flux. A meteorological station has been installed outside of the fence. In fiscal year 2007, two additional instrument nests are planned to be installed beneath the proposed barrier.

Pulsating-gliding transition in the dynamics of levitating liquid nitrogen droplets

International Nuclear Information System (INIS)

Snezhko, Alexey; Aranson, Igor S; Jacob, Eshel Ben

2008-01-01

Hot surfaces can cause levitation of small liquid droplets if the temperature is kept above the Leidenfrost point (220 0 C for water) due to the pressure formed because of rapid evaporation. Here, we demonstrate a new class of pulsating-gliding dynamic transitions in a special setting of the Leidenfrost effect at room temperatures and above a viscous fluid for droplets of liquid nitrogen. A whole range of highly dynamic patterns unfolds when droplets of liquid nitrogen are poured on the surface of another, more viscous liquid at room temperature. We also discovered that the levitating droplets induce vortex motion in the supporting viscous liquid. Depending on the viscosity of the supporting liquid, the nitrogen droplets either adopt an oscillating (pulsating) star-like shape with different azimuthal symmetries (from 2-9 petals) or glide on the surface with random trajectories. Thus, by varying the viscosity of the supporting liquid, we achieve controlled morphology and dynamics of Leidenfrost droplets

Pulsating-gliding transition in the dynamics of levitating liquid nitrogen droplets

Energy Technology Data Exchange (ETDEWEB)

Snezhko, Alexey; Aranson, Igor S [Materials Science Division, Argonne National Laboratory, 9700 S Cass Avenue, Argonne, IL 60439 (United States); Jacob, Eshel Ben [School of Physics and Astronomy, 69978 Tel Aviv University, Tel Aviv (Israel)], E-mail: aranson@msd.anl.gov

2008-04-15

Hot surfaces can cause levitation of small liquid droplets if the temperature is kept above the Leidenfrost point (220 {sup 0}C for water) due to the pressure formed because of rapid evaporation. Here, we demonstrate a new class of pulsating-gliding dynamic transitions in a special setting of the Leidenfrost effect at room temperatures and above a viscous fluid for droplets of liquid nitrogen. A whole range of highly dynamic patterns unfolds when droplets of liquid nitrogen are poured on the surface of another, more viscous liquid at room temperature. We also discovered that the levitating droplets induce vortex motion in the supporting viscous liquid. Depending on the viscosity of the supporting liquid, the nitrogen droplets either adopt an oscillating (pulsating) star-like shape with different azimuthal symmetries (from 2-9 petals) or glide on the surface with random trajectories. Thus, by varying the viscosity of the supporting liquid, we achieve controlled morphology and dynamics of Leidenfrost droplets.

Earth observation for rangeland monitoring

CSIR Research Space (South Africa)

Ramoelo, Abel

2012-10-01

Full Text Available .kashan.co.za] INTRODUCTION Grass nitrogen (N), as an indicator of rangeland quality, plays a crucial role in understanding the distribution, densities and feeding patterns of both wild herbivores and livestock. Zebras and livestock in the grazing and agricultural lands... ? How can grass nitrogen be mapped for assessing and monitoring of rangeland quality at wider or regional scales? ? Conventional point-based techniques for assessing rangeland quality proved to be expensive, laborious and time consuming...

Measurement of nitrogen dioxide in the air

Energy Technology Data Exchange (ETDEWEB)

Monteriolo, S C; Bertolaccini, M A

1973-01-01

A comparative study of automatic analytical methods for the monitoring of nitric oxide and nitrogen dioxide in the air indicates the need for a correct chemical conversion of the nonmeasurable species into the measurable species to obtain dependable results. The automatic colorimetric and chemiluminescent methods were compared to the manual colorimeter, and the electrochemical method was compared to chemiluminescence. Average, minimum, and maximum values are given for each comparison. All three methods are equally valid, in response linearity, sensitivity, and concentration limit, for the determination of nitric oxide, the measurable species. The determination of nitrogen dioxide, however, is strictly dependent on the efficiency of the conversion of the non-measurable species into the measurable form.

Very-high resolution monitoring of mass movement of surface material movements within a landslide

OpenAIRE

Clapuyt, François; Vanacker, Veerle; Van Oost, Kristof

2015-01-01

UAV-based aerial pictures processed with Structurefrom- Motion algorithms provide an efficient, low-cost and rapid framework for remote monitoring of dynamic environments. This methodology is particularly suitable for repeated topographic surveys in remote or poorly accessible areas. The aim of the study is to assess differential movement of surface material within a landslide located in the northern foothills of the Swiss Alps based on a time series of digital surface models derived from the...

Total pollution effect of urban surface runoff.

Science.gov (United States)

Luo, Hongbing; Luo, Lin; Huang, Gu; Liu, Ping; Li, Jingxian; Hu, Sheng; Wang, Fuxiang; Xu, Rui; Huang, Xiaoxue

2009-01-01

For pollution research with regard to urban surface runoff, most sampling strategies to date have focused on differences in land usage. With single land-use sampling, total surface runoff pollution effect cannot be evaluated unless every land usage spot is monitored. Through a new sampling strategy known as mixed stormwater sampling for a street community at discharge outlet adjacent to river, this study assessed the total urban surface runoff pollution effect caused by a variety of land uses and the pollutants washed off from the rain pipe system in the Futian River watershed in Shenzhen City of China. The water quality monitoring indices were COD (chemical oxygen demand), TSS (total suspend solid), TP (total phosphorus), TN (total nitrogen) and BOD (biochemical oxygen demand). The sums of total pollution loads discharged into the river for the four indices of COD, TSS, TN, and TP over all seven rainfall events were very different. The mathematical model for simulating total pollution loads was established from discharge outlet mixed stormwater sampling of total pollution loads on the basis of four parameters: rainfall intensity, total land area, impervious land area, and pervious land area. In order to treat surface runoff pollution, the values of MFF30 (mass first flush ratio) and FF30 (first 30% of runoff volume) can be considered as split-flow control criteria to obtain more effective and economical design of structural BMPs (best management practices) facilities.

The Global Nitrogen Cycle

Science.gov (United States)

Galloway, J. N.

2003-12-01

Once upon a time nitrogen did not exist. Today it does. In the intervening time the universe was formed, nitrogen was created, the Earth came into existence, and its atmosphere and oceans were formed! In this analysis of the Earth's nitrogen cycle, I start with an overview of these important events relative to nitrogen and then move on to the more traditional analysis of the nitrogen cycle itself and the role of humans in its alteration.The universe is ˜15 Gyr old. Even after its formation, there was still a period when nitrogen did not exist. It took ˜300 thousand years after the big bang for the Universe to cool enough to create atoms; hydrogen and helium formed first. Nitrogen was formed in the stars through the process of nucleosynthesis. When a star's helium mass becomes great enough to reach the necessary pressure and temperature, helium begins to fuse into still heavier elements, including nitrogen.Approximately 10 Gyr elapsed before Earth was formed (˜4.5 Ga (billion years ago)) by the accumulation of pre-assembled materials in a multistage process. Assuming that N2 was the predominate nitrogen species in these materials and given that the temperature of space is -270 °C, N2 was probably a solid when the Earth was formed since its boiling point (b.p.) and melting point (m.p.) are -196 °C and -210 °C, respectively. Towards the end of the accumulation period, temperatures were probably high enough for significant melting of some of the accumulated material. The volcanic gases emitted by the resulting volcanism strongly influenced the surface environment. Nitrogen was converted from a solid to a gas and emitted as N2. Carbon and sulfur were probably emitted as CO and H2S (Holland, 1984). N2 is still the most common nitrogen volcanic gas emitted today at a rate of ˜2 TgN yr-1 (Jaffee, 1992).Once emitted, the gases either remained in the atmosphere or were deposited to the Earth's surface, thus continuing the process of biogeochemical cycling. The rate of

Radiation contamination monitors

International Nuclear Information System (INIS)

Kato, Tsutomu; Iba, Hiroshi; Sato, Hiroshi

1999-01-01

To make sure of no contamination on people, used articles and working uniforms coming out of the radiation controlled area, nuclear power plants are equipped with radioactive contamination monitors. This paper outlines the basic specifications and advantages of our personnel surface contamination monitors to inspect whole-body surface contamination of people coming out, article surface contamination monitors to inspect the surface and inside contamination of used articles brought out, laundry monitors to inspect surface contamination of working uniforms used in the area before and after a wash, and whole-body counters to inspect and measure the internal contamination of a person out of the area. (author)

Dissolved organic nitrogen (DON) losses from nested artificially drained lowland catchments with contrasting soil types

Science.gov (United States)

Tiemeyer, Bärbel; Kahle, Petra; Lennartz, Bernd

2010-05-01

Artificial drainage is a common practice to improve moisture and aeration conditions of agricultural land. It shortens the residence time of water in the soil and may therefore contribute to the degradation of peatlands as well as to the still elevated level of diffuse pollution of surface water bodies, particularly if flow anomalies like preferential flow cause a further acceleration of water and solute fluxes. Especially in the case of nitrate, artificially drained sub-catchments are found to control the catchment-scale nitrate losses. However, it is frequently found that nitrate losses and nitrogen field balances do not match. At the same time, organic fertilizers are commonly applied and, especially in lowland catchments, organic soils have been drained for agricultural use. Thus, the question arises whether dissolved organic nitrogen (DON) forms an important component of the nitrogen losses from artificially drained catchments. However, in contrast to nitrate and even to dissolved organic carbon (DOC), this component is frequently overlooked, especially in nested catchment studies with different soil types and variable land use. Here, we will present data from a hierarchical water quantity and quality measurement programme in the federal state Mecklenburg-Vorpommern (North-Eastern Germany). The monitoring programme in the pleistocene lowland catchment comprises automatic sampling stations at a collector drain outlet (4.2 ha catchment), at a ditch draining arable land on mineral soils (179 ha), at a ditch mainly draining grassland on organic soils (85 ha) and at a brook with a small rural catchment (15.5 km²) of mixed land use and soil types. At all sampling stations, daily to weekly composite samples were taken, while the discharge and the meteorological data were recorded continuously. Water samples were analyzed for nitrate-nitrogen, ammonium-nitrogen and total nitrogen. We will compare two years: 2006/07 was a very wet year (P = 934 mm) with a high summer

Molecular nitrogen fixation and nitrogen cycle in nature

Energy Technology Data Exchange (ETDEWEB)

Virtanen, A I

1952-01-01

The origin of nitrogen oxides in the atmosphere is discussed. Evidently only a small proportion of the nitrate-and nitrite-nitrogen found in the precipitation is formed through electric discharges from molecular nitrogen, photochemical nitrogen fixation being probably of greater importance. Formation of nitrate nitrogen through atmospheric oxidation of nitrous oxide (N/sub 2/O) evaporating from the soil is also considered likely. Determination of nitrogen compounds at different altitudes is indispensable for gaining information of the N/sub 2/-fixation in the atmosphere and, in general, of the origin of nitrogen oxides and their decomposition. International cooperation is needed for this as well as for the quantitative determination of the nitrogen compounds removed from the soil by leaching and brought by waters into the seas.

AFRRI TRIGA Reactor water quality monitoring program

International Nuclear Information System (INIS)

Moore, Mark; George, Robert; Spence, Harry; Nguyen, John

1992-01-01

AFRRI has started a water quality monitoring program to provide base line data for early detection of tank leaks. This program revealed problems with growth of algae and bacteria in the pool as a result of contamination with nitrogenous matter. Steps have been taken to reduce the nitrogen levels and to kill and remove algae and bacteria from the reactor pool. (author)

A tradeoff frontier for global nitrogen use and cereal production

International Nuclear Information System (INIS)

Mueller, Nathaniel D; West, Paul C; Gerber, James S; MacDonald, Graham K; Foley, Jonathan A; Polasky, Stephen

2014-01-01

Nitrogen fertilizer use across the world’s croplands enables high-yielding agricultural production, but does so at considerable environmental cost. Imbalances between nitrogen applied and nitrogen used by crops contributes to excess nitrogen in the environment, with negative consequences for water quality, air quality, and climate change. Here we utilize crop input-yield models to investigate how to minimize nitrogen application while achieving crop production targets. We construct a tradeoff frontier that estimates the minimum nitrogen fertilizer needed to produce a range of maize, wheat, and rice production levels. Additionally, we explore potential environmental consequences by calculating excess nitrogen along the frontier using a soil surface nitrogen balance model. We find considerable opportunity to achieve greater production and decrease both nitrogen application and post-harvest excess nitrogen. Our results suggest that current (circa 2000) levels of cereal production could be achieved with ∼50% less nitrogen application and ∼60% less excess nitrogen. If current global nitrogen application were held constant but spatially redistributed, production could increase ∼30%. If current excess nitrogen were held constant, production could increase ∼40%. Efficient spatial patterns of nitrogen use on the frontier involve substantial reductions in many high-use areas and moderate increases in many low-use areas. Such changes may be difficult to achieve in practice due to infrastructure, economic, or political constraints. Increases in agronomic efficiency would expand the frontier to allow greater production and environmental gains

A comparison of total bound nitrogen with the sum of inorganic nitrogen in the present partice in the German Water Regulation Act for monitoring of nitrogen compounds; Ein Vergleich des gesamten gebundenen Stickstoffs mit der Summe des anorganischen Stickstoffs in der derzeitigen Gesetzespraxis zur Ueberwachung auf Stickstoffverbindungen

Energy Technology Data Exchange (ETDEWEB)

Rinne, D.; Seckert-Knopp, W. [Landesamt fuer Wasserwirtschaft Rheinland-Pfalz, Mainz (Germany)

1997-11-01

The results of the analysis of nitrate, nitrite, ammonia, and total bound nitrogen (TN{sub b}) from 331 samples of municipal and 322 samples of industrial waste water effluents were compiled in the years 1990 to 1994. These data were evaluated due to - the comparison of the sum of inorganic nitrogen ({Sigma} N{sub anorg.}) of nitrate, nitrite, and ammonia to TN{sub b} in view of a planned exchange in the German Waste Water Regulation Act - the calculation of organic bound nitrogen (N{sub org.}) - the usefulness to generate sufficient data for balancing the `content of nitrogen` in water systems. The results of our investigations are: The analytical results from the sum of inorganic nitrogen and TN{sub b} are in very good agreement. In most cases the TN{sub b} values were higher than those of {Sigma} N{sub anorg.} This is plausible because most samples contain a certain amount of organic bound nitrogen. Therefore the differences between the results of this two analytical parameters should express the term `organic bound nitrogen` (N{sub org.}). This substraction is an excellent method to estimate this value without a further analytical procedure. The data from our investigation underline this quite clearly. In contrary to the determination of the single compounds ammonia, nitrate, and nitrite the TN{sub b} as a sum parameter is fast, instrument based, can be automated and shows a sufficient limit of determination. This method allows the evaluation of a high data density for water monitoring and balancing the `content of nitrogen` in water systems. A further advantage is the minimizing of errors when applying only one analytical method instead of three. (orig.) [Deutsch] Die Analysenergebnisse der Parameter Nitrit, Nitrat, Ammonium sowie die davon abgeleiteten Parameter `Summe anorganischer Stickstoff` ({Sigma} N{sub anorg.}) und `gesamter gebundener Stickstoff` (TN{sub b}) wurden fuer 331 Proben kommunaler und 322 Proben industrieller Abwasseranlagen aus den Jahren

Growth of nitrogen-doped graphene on copper: Multiscale simulations

Science.gov (United States)

Gaillard, P.; Schoenhalz, A. L.; Moskovkin, P.; Lucas, S.; Henrard, L.

2016-02-01

We used multiscale simulations to model the growth of nitrogen-doped graphene on a copper substrate by chemical vapour deposition (CVD). Our simulations are based on ab-initio calculations of energy barriers for surface diffusion, which are complemented by larger scale Kinetic Monte Carlo (KMC) simulations. Our results indicate that the shape of grown doped graphene flakes depends on the temperature and deposition flux they are submitted during the process, but we found no significant effect of nitrogen doping on this shape. However, we show that nitrogen atoms have a preference for pyridine-like sites compared to graphite-like sites, as observed experimentally.

Nitrogen transport during ion nitriding of austenitic stainless steel

International Nuclear Information System (INIS)

Parascandola, S.

2001-09-01

The work is structured as follows: In Chapter 2 fundamental transport concepts and phenomena and approaches to transport modeling are introduced. In Chapter 3 details are presented concerning the material under investigation, the material modification process, and the ion beam analytical techniques. In Chapter 4 experimental and modeling results are presented and discussed. Issues that are directly addressed include: The structural nature of the nitrogen enriched layer. The diffusion mechanism of nitrogen. The role of potential incorporation and release mechanisms. The evolution of the thickness of the nitrogen enriched layer. The role of the surface oxide layer. (orig.)

System implementation of hazard analysis and critical control points (HACCP) in a nitrogen production plant

International Nuclear Information System (INIS)

Barrantes Salazar, Alexandra

2014-01-01

System of hazard analysis and critical control points are deployed in a production plant of liquid nitrogen. The fact that the nitrogen has become a complement to food packaging to increase shelf life, or provide a surface that protect it from manipulation, has been the main objective. Analysis of critical control points for the nitrogen production plant has been the adapted methodology. The knowledge of both the standard and the production process, as well as the on site verification process, have been necessary. In addition, all materials and/or processing units that are found in contact with the raw material or the product under study were evaluated. Such a way that the intrinsic risks of each were detected, from the physical, chemical and biological points of view according to the origin or pollution source. For each found risk was evaluated the probability of occurrence according to the frequency and gravity of it, with these variables determined was achieved the definition of the type of risk detected. In the cases that was presented a greater risk or critical, these were subjected decision tree; with which is concluded the non determination of critical control points. However, for each one of them were established the maximum permitted limits. To generate each of the results it has literature or scientific reference of reliable provenance, where is indicated properly the support of the evaluated matter. In a general way, the material matrix and the process matrix are found without critical control points; so that the project is concluded in the analysis, and it has to generate without the monitoring system and verification. To increase this project is suggested in order to cover the packaging system of gaseous nitrogen, due to it was delimited to liquid nitrogen. Furthermore, the liquid nitrogen is a 100% automated and closed process so the introduction of contaminants is very reduced, unlike the gaseous nitrogen process. (author) [es

Optimal river monitoring network using optimal partition analysis: a case study of Hun River, Northeast China.

Science.gov (United States)

Wang, Hui; Liu, Chunyue; Rong, Luge; Wang, Xiaoxu; Sun, Lina; Luo, Qing; Wu, Hao

2018-01-09

River monitoring networks play an important role in water environmental management and assessment, and it is critical to develop an appropriate method to optimize the monitoring network. In this study, an effective method was proposed based on the attainment rate of National Grade III water quality, optimal partition analysis and Euclidean distance, and Hun River was taken as a method validation case. There were 7 sampling sites in the monitoring network of the Hun River, and 17 monitoring items were analyzed once a month during January 2009 to December 2010. The results showed that the main monitoring items in the surface water of Hun River were ammonia nitrogen (NH 4 + -N), chemical oxygen demand, and biochemical oxygen demand. After optimization, the required number of monitoring sites was reduced from seven to three, and 57% of the cost was saved. In addition, there were no significant differences between non-optimized and optimized monitoring networks, and the optimized monitoring networks could correctly represent the original monitoring network. The duplicate setting degree of monitoring sites decreased after optimization, and the rationality of the monitoring network was improved. Therefore, the optimal method was identified as feasible, efficient, and economic.

T Tank Farm Interim Surface Barrier Demonstration -- Vadose Zone Monitoring FY07 Report

International Nuclear Information System (INIS)

Zhang, Z. F.; Strickland, Christopher E.; Keller, Jason M.; Wittreich, Curtis D.; Sydnor, Harold A.

2008-01-01

CH2M HILL Hanford Group, Inc. is currently in the process of constructing a temporary surface barrier over a portion of the T Tank Farm as part of the T farm Interim Surface Barrier Demonstration Project. The surface barrier is designed to prevent the infiltration of precipitation into the contaminated soil zone created by the Tank T-106 leak and minimize movement of the contamination. As part of the demonstration effort, vadose zone moisture monitoring is being performed to assess the effectiveness of the barrier at reducing soil moisture. A solar-powered and remotely-controlled system was installed to continuously monitor soil water conditions in four instrument nests (i.e., A, B, C, and D) and the site meteorological condition. Each instrument nest was composed of a capacitance probe with multiple sensors, multiple heat-dissipation units, a neutron probe access tube and a datalogger. Nests A and B also contained a drain gauge each. The principle variables monitored for this purpose are soil-water content, soil-water pressure, and soil-water flux. In addition to these, soil temperature, precipitation, and air temperature are measured. Data from each of the dataloggers were transmitted remotely to the receiving computer. The neutron probe access tube was used to perform quarterly manual measurements of soil-water content using a neutron probe. This monitoring system was used to assess the soil water conditions in the soil outside and within the footprint of the surface barrier to be emplaced in the Hanford T Tank Farm. Data to date is baseline under the condition without the interim surface barrier in place. All the instruments except the two drain gauges were functional in FY07. The capacitance-probe measurements showed that the soil-moisture content at relatively shallow depths (e.g., 0.6 and 0.9 m) was increasing since October 2006 and reached the highest in early January 2007 followed by a slight decrease. Soil-moisture contents at the depths of 1.3 m and

Influence of surface chemistry of carbon materials on their interactions with inorganic nitrogen contaminants in soil and water.

Science.gov (United States)

Sumaraj; Padhye, Lokesh P

2017-10-01

Inorganic nitrogen contaminants (INC) (NH 4 + , NO 3 - , NO 2 - , NH 3 , NO, NO 2 , and N 2 O) pose a growing risk to the environment, and their remediation methods are highly sought after. Application of carbon materials (CM), such as biochar and activated carbon, to remediate INC from agricultural fields and wastewater treatment plants has gained a significant interest since past few years. Understanding the role of surface chemistry of CM in adsorption of various INC is highly critical to increase adsorption efficiency as well as to assess the long term impact of using these highly recalcitrant CM for remediation of INC. Critical reviews of adsorption studies related to INC have revealed that carbon surface chemistry (surface functional groups, pH, Eh, elemental composition, and mineral content) has significant influence on adsorption of INC. Compared to basic functional groups, oxygen containing surface functional groups have been found to be more influential for adsorption of INC. However, basic sites on carbon materials still play an important role in chemisorption of anionic INC. Apart from surface functional groups, pH, Eh and pH zpc of CM and elemental and mineral composition of its surface are important properties capable of altering INC interactions with CM. This review summarizes our current understanding of INC interactions with CM's surface through the known chemisorption mechanisms: electrostatic interaction, hydrogen bonding, electron donor-acceptor mechanism, hydrophobic and hydrophilic interaction, chemisorption aided by minerals, and interactions influenced by pH and elemental composition. Change in surface chemistry of CM in soil during aging is also discussed. Copyright © 2017 Elsevier Ltd. All rights reserved.

Nitrogen transformations in wetlands: Effects of water flow patterns

Energy Technology Data Exchange (ETDEWEB)

Davidsson, T.

1997-11-01

In this thesis, I have studied nitrogen turnover processes in water meadows. A water meadow is a wetland where water infiltrates through the soil of a grassland field. It is hypothesized that infiltration of water through the soil matrix promotes nutrient transformations compared to surface flow of water, by increasing the contact between water, nutrients, soil organic matter and bacteria. I have studied how the balance between nitrogen removal (denitrification, assimilative uptake, adsorption) and release (mineralization, desorption) processes are affected by water flow characteristics. Mass balance studies and direct denitrification measurements at two field sites showed that, although denitrification was high, net nitrogen removal in the water meadows was poor. This was due to release of ammonium and dissolved organic nitrogen (DON) from the soils. In laboratory studies, using {sup 15}N isotope techniques, I have shown that nitrogen turnover is considerably affected by hydrological conditions and by soil type. Infiltration increased virtually all the nitrogen processes, due to deeper penetration of nitrate and oxygen, and extended zones of turnover processes. On the contrary, soils and sediments with surface water flow, diffusion is the main transfer mechanism. The relation between release and removal processes sometimes resulted in shifts towards net nitrogen production. This occurred in infiltration treatments when ammonium efflux was high in relation to denitrification. It was concluded that ammonium and DON was of soil origin and hence not a product of dissimilatory nitrate reduction to ammonium. Both denitrification potential and mineralization rates were higher in peaty than in sandy soil. Vertical or horizontal subsurface flow is substantial in many wetland types, such as riparian zones, tidal salt marshes, fens, root-zone systems and water meadows. Moreover, any environment where aquatic and terrestrial ecosystems meet, and where water level fluctuates

40 CFR 76.14 - Monitoring, recordkeeping, and reporting.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 16 2010-07-01 2010-07-01 false Monitoring, recordkeeping, and reporting. 76.14 Section 76.14 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) ACID RAIN NITROGEN OXIDES EMISSION REDUCTION PROGRAM § 76.14 Monitoring, recordkeeping...

Nitrate variability in groundwater of North Carolina using monitoring and private well data models.

Science.gov (United States)

Messier, Kyle P; Kane, Evan; Bolich, Rick; Serre, Marc L

2014-09-16

Nitrate (NO3-) is a widespread contaminant of groundwater and surface water across the United States that has deleterious effects to human and ecological health. This study develops a model for predicting point-level groundwater NO3- at a state scale for monitoring wells and private wells of North Carolina. A land use regression (LUR) model selection procedure is developed for determining nonlinear model explanatory variables when they are known to be correlated. Bayesian Maximum Entropy (BME) is used to integrate the LUR model to create a LUR-BME model of spatial/temporal varying groundwater NO3- concentrations. LUR-BME results in a leave-one-out cross-validation r2 of 0.74 and 0.33 for monitoring and private wells, effectively predicting within spatial covariance ranges. Results show significant differences in the spatial distribution of groundwater NO3- contamination in monitoring versus private wells; high NO3- concentrations in the southeastern plains of North Carolina; and wastewater treatment residuals and swine confined animal feeding operations as local sources of NO3- in monitoring wells. Results are of interest to agencies that regulate drinking water sources or monitor health outcomes from ingestion of drinking water. Lastly, LUR-BME model estimates can be integrated into surface water models for more accurate management of nonpoint sources of nitrogen.

Nitrogen contribution to tribological behaviour improvement of titanium alloys

International Nuclear Information System (INIS)

Corre, Y.; Lebrun, J.P.; Douet, M.

1996-01-01

Titanium an titanium alloys are more used materials in mechanical applications. A low density and very interesting mechanical characteristics present these materials as a first choice in many fields (aeronautics, automobile precision mechanics, biomedical...). Nevertheless, their poor tribological qualities often negate them as a friction surface. Modifying their surface properties is thus a real concern. The introduction of nitrogen on the surface enables a significant improvement to the tribological behaviour of these materials. Nitrogen ionic implantation is a technique used in titanium alloy surface treatment. Industrial applications of this process are numerous (biomedical, aeronautics...) but the limitations its (essentially treatment depth) prevent its use in certain cases. The increase in treatment temperature can overcome these limitations. Thus, the analysis of the properties obtained after treatment at various temperatures (20 deg. C) enables us to find the best compromise between metallurgic, geometrical properties (surface condition, deformation) and friction properties. This compromise enables us to solve a majority of tribological problems of titanium alloys. (authors). 7 refs., 10 figs., 2 tabs., 1 photo

Surface modification of highly oriented pyrolytic graphite by reaction with atomic nitrogen at high temperatures

International Nuclear Information System (INIS)

Zhang Luning; Pejakovic, Dusan A.; Geng Baisong; Marschall, Jochen

2011-01-01

Dry etching of {0 0 0 1} basal planes of highly oriented pyrolytic graphite (HOPG) using active nitridation by nitrogen atoms was investigated at low pressures and high temperatures. The etching process produces channels at grain boundaries and pits whose shapes depend on the reaction temperature. For temperatures below 600 deg. C, the majority of pits are nearly circular, with a small fraction of hexagonal pits with rounded edges. For temperatures above 600 deg. C, the pits are almost exclusively hexagonal with straight edges. The Raman spectra of samples etched at 1000 deg. C show the D mode near 1360 cm -1 , which is absent in pristine HOPG. For deep hexagonal pits that penetrate many graphene layers, neither the surface number density of pits nor the width of pit size distribution changes substantially with the nitridation time, suggesting that these pits are initiated at a fixed number of extended defects intersecting {0 0 0 1} planes. Shallow pits that penetrate 1-2 graphene layers have a wide size distribution, which suggests that these pits are initiated on pristine graphene surfaces from lattice vacancies continually formed by N atoms. A similar wide size distribution of shallow hexagonal pits is observed in an n-layer graphene sample after N-atom etching.

Design and evaluation of an inexpensive radiation shield for monitoring surface air temperatures

Science.gov (United States)

Zachary A. Holden; Anna E. Klene; Robert F. Keefe; Gretchen G. Moisen

2013-01-01

Inexpensive temperature sensors are widely used in agricultural and forestry research. This paper describes a low-cost (~3 USD) radiation shield (radshield) designed for monitoring surface air temperatures in harsh outdoor environments. We compared the performance of the radshield paired with low-cost temperature sensors at three sites in western Montana to several...

Removal of sulfur and nitrogen containing pollutants from discharge gases

Energy Technology Data Exchange (ETDEWEB)

Joubert, James I. (Pittsburgh, PA)

1986-01-01

Oxides of sulfur and of nitrogen are removed from waste gases by reaction with an unsupported copper oxide powder to form copper sulfate. The resulting copper sulfate is dissolved in water to effect separation from insoluble mineral ash and dried to form solid copper sulfate pentahydrate. This solid sulfate is thermally decomposed to finely divided copper oxide powder with high specific surface area. The copper oxide powder is recycled into contact with the waste gases requiring cleanup. A reducing gas can be introduced to convert the oxide of nitrogen pollutants to nitrogen.

Removal of sulfur and nitrogen containing pollutants from discharge gases

Energy Technology Data Exchange (ETDEWEB)

Joubert, J.I.

1985-02-08

Oxides of sulfur and of nitrogen are removed from waste gases by reaction with an unsupported copper oxide powder to form copper sulfate. The resulting copper sulfate is dissolved in water to effect separation from insoluble mineral ash and dried to form solid copper sulfate pentahydrate. This solid sulfate is thermally decomposed to finely divided copper oxide powder with high specific surface area. The copper oxide powder is recycled into contact with the waste gases requiring cleanup. A reducing gas can be introduced to convert the oxide of nitrogen pollutants to nitrogen.

Quantum Control of a Nitrogen-Vacancy Center using Surface Acoustic Waves in the Resolved Sideband Limit

Science.gov (United States)

Golter, David; Oo, Thein; Amezcua, Maira; Wang, Hailin

Micro-electromechanical systems research is producing increasingly sophisticated tools for nanophononic applications. Such technology is well-suited for achieving chip-based, integrated acoustic control of solid-state quantum systems. We demonstrate such acoustic control in an important solid-state qubit, the diamond nitrogen-vacancy (NV) center. Using an interdigitated transducer to generate a surface acoustic wave (SAW) field in a bulk diamond, we observe phonon-assisted sidebands in the optical excitation spectrum of a single NV center. This exploits the strong strain sensitivity of the NV excited states. The mechanical frequencies far exceed the relevant optical linewidths, reaching the resolved-sideband regime. This enables us to use the SAW field for driving Rabi oscillations on the phonon-assisted optical transition. These results stimulate the further integration of SAW-based technologies with the NV center system.

Accuracy evaluation of the optical surface monitoring system on EDGE linear accelerator in a phantom study.

Science.gov (United States)

Mancosu, Pietro; Fogliata, Antonella; Stravato, Antonella; Tomatis, Stefano; Cozzi, Luca; Scorsetti, Marta

2016-01-01

Frameless stereotactic radiosurgery (SRS) requires dedicated systems to monitor the patient position during the treatment to avoid target underdosage due to involuntary shift. The optical surface monitoring system (OSMS) is here evaluated in a phantom-based study. The new EDGE linear accelerator from Varian (Varian, Palo Alto, CA) integrates, for cranial lesions, the common cone beam computed tomography (CBCT) and kV-MV portal images to the optical surface monitoring system (OSMS), a device able to detect real-time patient׳s face movements in all 6 couch axes (vertical, longitudinal, lateral, rotation along the vertical axis, pitch, and roll). We have evaluated the OSMS imaging capability in checking the phantoms׳ position and monitoring its motion. With this aim, a home-made cranial phantom was developed to evaluate the OSMS accuracy in 4 different experiments: (1) comparison with CBCT in isocenter location, (2) capability to recognize predefined shifts up to 2° or 3cm, (3) evaluation at different couch angles, (4) ability to properly reconstruct the surface when the linac gantry visually block one of the cameras. The OSMS system showed, with a phantom, to be accurate for positioning in respect to the CBCT imaging system with differences of 0.6 ± 0.3mm for linear vector displacement, with a maximum rotational inaccuracy of 0.3°. OSMS presented an accuracy of 0.3mm for displacement up to 1cm and 1°, and 0.5mm for larger displacements. Different couch angles (45° and 90°) induced a mean vector uncertainty < 0.4mm. Coverage of 1 camera produced an uncertainty < 0.5mm. Translations and rotations of a phantom can be accurately detect with the optical surface detector system. Copyright © 2016 American Association of Medical Dosimetrists. Published by Elsevier Inc. All rights reserved.

Nitrogen

Science.gov (United States)

Apodaca, Lori E.

2013-01-01

The article presents an overview of the nitrogen chemical market as of July 2013, including the production of ammonia compounds. Industrial uses for ammonia include fertilizers, explosives, and plastics. Other topics include industrial capacity of U.S. ammonia producers CF Industries Holdings Inc., Koch Nitrogen Co., PCS Nitrogen, Inc., and Agrium Inc., the impact of natural gas prices on the nitrogen industry, and demand for corn crops for ethanol production.

Fate of Deposited Nitrogen in Tropical Forests in Southern China

DEFF Research Database (Denmark)

Gurmesa, Geshere Abdisa

and denitrification from the ecosystem. Loss of N, in turn, has many negative consequences, including soil and surface water acidification, plant nutrient imbalances and related adverse effects on biological diversities. Increased atmospheric N deposition that is anticipated for tropical regions may further aggravate...... as N export in soil water in tropical forests. Total annual atmospheric deposition of N to the forest in the study period was 51 kg N ha-1yr-1. Nitrogen deposition was dominated by NH4-N due to intensive agricultural NH3 emissions in nearby areas. Nitrate dominated leaching loss from the soil...... after the last addition and by monitoring leaching of 15N in soil water on a monthly basis. The result showed that deposited N is effectively retained in plant and soil pools resembling and exceeding that observed for temperate forests. Furthermore, increased N input decreased the N retention efficiency...

Nitrogen-doped porous “green carbon” derived from shrimp shell: Combined effects of pore sizes and nitrogen doping on the performance of lithium sulfur battery

Energy Technology Data Exchange (ETDEWEB)

Qu, Jiangying, E-mail: qujy@lnnu.edu.cn [Faculty of Chemistry and Chemical Engineering, Liaoning Normal University, Dalian, 116029 (China); Carbon Research Laboratory, Center for Nano Materials and Science, School of Chemical Engineering, State Key Lab of Fine Chemicals, Dalian University of Technology, Dalian, 116024 (China); Lv, Siyuan; Peng, Xiyue; Tian, Shuo; Wang, Jia [Faculty of Chemistry and Chemical Engineering, Liaoning Normal University, Dalian, 116029 (China); Gao, Feng, E-mail: fenggao2003@163.com [Faculty of Chemistry and Chemical Engineering, Liaoning Normal University, Dalian, 116029 (China); Carbon Research Laboratory, Center for Nano Materials and Science, School of Chemical Engineering, State Key Lab of Fine Chemicals, Dalian University of Technology, Dalian, 116024 (China)

2016-06-25

Nitrogen-rich porous “green carbons” derived from abundant shrimp shell shows good performance for Li–S batteries. The strategy in this work is highlighted to selective removal of intrinsic CaCO{sub 3} in shrimp shell followed by KOH activation to tune the pore sizes of the obtained carbons. On the basis of the different porous structures, the discharge capacity of the obtained carbons as Li–S cathodes follows the order of micro-mesoporous carbon>mesoporous carbon>microporous carbon. The high capacity of the micro-mesoporous carbon is attributed to its positive characters such as the coexistence of micro-mesoporous structure, the large pore volume and the high specific surface area. Furthermore, well-dispersed nitrogen in the porous carbons is naturally doped and inherited from shrimp shell, and can help to enhance cycle stability when used as cathodes. As a result, all carbon cathodes exhibit the good cycle stability (>78%) due to their nitrogen doping induced chemical adsorption of sulfur on the surface areas of the porous carbons. Among them, mesoporous carbon cathode shows the best cycle stability with 90% retention within 100 cycles, which is mainly attributed to the synergistic effects of its both large pore size (5.12 nm) and high nitrogen content (6.67 wt %). - Highlights: • Nitrogen-rich porous “green carbons” derived from abundant shrimp shell shows good performance for Li–S batteries. • Intrinsic CaCO{sub 3} in shrimp shell as the natural template plays an important role on tailoring of the pore sizes of the porous carbons. • Nitrogen containing polysaccharide in shrimp shell benefits to produce nitrogen-rich carbons. • The effects of pore sizes on the electrochemical performance are investigated in detail. • The carbon-sulfur cathodes exhibit the good cycle stability because of nitrogen doping induced chemical adsorption of sulfur.

Nitrogen-doped porous “green carbon” derived from shrimp shell: Combined effects of pore sizes and nitrogen doping on the performance of lithium sulfur battery

International Nuclear Information System (INIS)

Qu, Jiangying; Lv, Siyuan; Peng, Xiyue; Tian, Shuo; Wang, Jia; Gao, Feng

2016-01-01

Nitrogen-rich porous “green carbons” derived from abundant shrimp shell shows good performance for Li–S batteries. The strategy in this work is highlighted to selective removal of intrinsic CaCO_3 in shrimp shell followed by KOH activation to tune the pore sizes of the obtained carbons. On the basis of the different porous structures, the discharge capacity of the obtained carbons as Li–S cathodes follows the order of micro-mesoporous carbon>mesoporous carbon>microporous carbon. The high capacity of the micro-mesoporous carbon is attributed to its positive characters such as the coexistence of micro-mesoporous structure, the large pore volume and the high specific surface area. Furthermore, well-dispersed nitrogen in the porous carbons is naturally doped and inherited from shrimp shell, and can help to enhance cycle stability when used as cathodes. As a result, all carbon cathodes exhibit the good cycle stability (>78%) due to their nitrogen doping induced chemical adsorption of sulfur on the surface areas of the porous carbons. Among them, mesoporous carbon cathode shows the best cycle stability with 90% retention within 100 cycles, which is mainly attributed to the synergistic effects of its both large pore size (5.12 nm) and high nitrogen content (6.67 wt %). - Highlights: • Nitrogen-rich porous “green carbons” derived from abundant shrimp shell shows good performance for Li–S batteries. • Intrinsic CaCO_3 in shrimp shell as the natural template plays an important role on tailoring of the pore sizes of the porous carbons. • Nitrogen containing polysaccharide in shrimp shell benefits to produce nitrogen-rich carbons. • The effects of pore sizes on the electrochemical performance are investigated in detail. • The carbon-sulfur cathodes exhibit the good cycle stability because of nitrogen doping induced chemical adsorption of sulfur.

Electrical properties of MOS structures on nitrogen-doped Czochralski-grown silicon: A positron annihilation study

International Nuclear Information System (INIS)

Slugen, V.; Harmatha, L.; Tapajna, M.; Ballo, P.; Pisecny, P.; Sik, J.; Koegel, G.; Krsjak, V.

2006-01-01

Measurements of interface trap density, effective generation lifetime (GL) and effective surface generation velocity have been performed using different methods on selected MOS structures prepared on nitrogen-doped Czochralski-grown (NCz) silicon. The application of the positron annihilation technique using a pulsed low energy positron system (PLEPS) focused on the detection of nitrogen-related defects in NCz silicon in the near surface region. In the case of p-type Cz silicon, all the results could be used for the testing of homogeneity. In n-type Cz silicon, positron annihilation was found insensitive to nitrogen doping

Nitrogen oxidative activation in the radiolysis process of dioxide hydrocarbon composition, oxygen-nitrogen over 3-d transition metals

International Nuclear Information System (INIS)

Rustamov, V.R.; Garibov, A.A.; Kerimov, V.K.; Aliyev, S.M.; Nasirova, Kh.Y.

2004-01-01

The radiochemical process of nitrogen fixation in carbon dioxide, oxygen-nitrogen composition in 3-d metal (iron, nickel) was studied. Bifunctional character of surface's role in the generation of radiolysis products was postulated: a) Chemisorption's of molecular ions (N 2 + , CO 2 + , O 2 + ) on the surface of metal and their dissociative neutralization. b) Coordination of nitrogen and carbon oxide being generated in nitrosyl and carbonyl-nitrosyl complex of iron and nickel. Total yield of the products is over the rang 6,4†7,5, to explain radiolysis' what contribution of only neutral products is impossible. Evidently in the generation of final products, defined contribution brings in molecular ions N 2 + (N + ) and CO 2 + . Interaction character of these ions with nickel proposes the formation of the relation between unpaired electrons N 2 + and CO 2 + with unfilled d-sub level of this metals with the nickel nitride generation [N i -N=N + ] and binding energy in ion diazotate decreases to twice. The yield of nitrogen dioxide on radiolysis of the air gave G NO2 =0,8±0,2 molecule/100eV which is proper to the date in the literature. Kinetic curve appears rapidly in the saturation. Air radiolysis over iron gave the following results: G NO 2 = 2,75 ± 0,25, G N 2 O = 9,0 ± 1,0 molecule/100eV. Thus total yield of radiolysis products is Σ G = 10,5 ± 12,0 molecule/100eV. (author)

Nitrogen oxidative activation in the radiolysis process of dioxide hydrocarbon composition, oxygen-nitrogen over 3-D transition metals

International Nuclear Information System (INIS)

Rustamov, V.R.; Garibov, A.A.; Kerimov, V.K.; Aliyev, S.M.; Nasirova, Kh.Y.

2004-01-01

Full text: The radiochemical process of nitrogen fixation in carbon dioxide, oxygen-nitrogen composition in 3-d metal (iron, nickel) was studied. Bifunctional character of surface's role in the generation of radiolysis products was postulated: a) Chemisorption's of molecular ions (N 2 + , CO 2 + , O 2 + ) on the surface of metal and their dissociative neutralization. b) Coordination of nitrogen and carbon oxide being generated in nitrosyl and carbonyl-nitrosyl complex of iron and nickel. Total yield of the products is over the rang 6,4†7,5, to explain radiolysis' what contribution of only neutral products is impossible. Evidently in the generation of final products, defined contribution brings in molecular ions N 2 + (N + ) and CO 2 + . Interaction character of these ions with nickel proposes the formation of the relation between unpaired electrons N 2 + and CO 2 + with unfilled d-sub level of this metals with the nickel nitride generation [N i -N=N + ] and binding energy in ion diazotate decreases to twice. The yield of nitrogen dioxide on radiolysis of the air gave G NO2 =0,8±0,2 molecule/100eV which is proper to the date in the literature. Kinetic curve appears rapidly in the saturation. Air radiolysis over iron gave the following results: G NO 2 = 2,75 ± 0,25, G N 2 O = 9,0 ± 1,0 molecule/100eV. Thus total yield of radiolysis products is Σ G = 10,5 ± 12,0 molecule/100eV

Africa-wide monitoring of small surface water bodies using multisource satellite data: a monitoring system for FEWS NET: chapter 5

Science.gov (United States)

Velpuri, Naga Manohar; Senay, Gabriel B.; Rowland, James; Verdin, James P.; Alemu, Henok; Melesse, Assefa M.; Abtew, Wossenu; Setegn, Shimelis G.

2014-01-01

Continental Africa has the highest volume of water stored in wetlands, large lakes, reservoirs, and rivers, yet it suffers from problems such as water availability and access. With climate change intensifying the hydrologic cycle and altering the distribution and frequency of rainfall, the problem of water availability and access will increase further. Famine Early Warning Systems Network (FEWS NET) funded by the United States Agency for International Development (USAID) has initiated a large-scale project to monitor small to medium surface water points in Africa. Under this project, multisource satellite data and hydrologic modeling techniques are integrated to monitor several hundreds of small to medium surface water points in Africa. This approach has been already tested to operationally monitor 41 water points in East Africa. The validation of modeled scaled depths with field-installed gauge data demonstrated the ability of the model to capture both the spatial patterns and seasonal variations. Modeled scaled estimates captured up to 60 % of the observed gauge variability with a mean root-mean-square error (RMSE) of 22 %. The data on relative water level, precipitation, and evapotranspiration (ETo) for water points in East and West Africa were modeled since 1998 and current information is being made available in near-real time. This chapter presents the approach, results from the East African study, and the first phase of expansion activities in the West Africa region. The water point monitoring network will be further expanded to cover much of sub-Saharan Africa. The goal of this study is to provide timely information on the water availability that would support already established FEWS NET activities in Africa. This chapter also presents the potential improvements in modeling approach to be implemented during future expansion in Africa.

Daily monitoring of the land surface of the Earth

Science.gov (United States)

Mascaro, J.

2016-12-01

Planet is an integrated aerospace and data analytics company that operates the largest fleet of Earth-imaging satellites. With more than 140 cube-sats successfully launched to date, Planet is now collecting approximately 10 million square kilometers of imagery per day (3-5m per pixel, in red, green, blue and near infrared spectral bands). By early 2017, Planet's constellation will image the entire land surface of the Earth on a daily basis. Due to investments in cloud storage and computing, approximately 75% of imagery collected is available to Planet's partners within 24 hours of capture through an Application Program Interface. This unique dataset has enormous applications for monitoring the status of Earth's natural ecosystems, as well as human settlements and agricultural welfare. Through our Ambassadors Program, Planet has made data available for researchers in areas as disparate as human rights monitoring in refugee camps, to assessments of the impact of hydroelectric installations, to tracking illegal gold mining in Amazon forests, to assessing the status of the cryosphere. Here, we share early results from Planet's research partner network, including enhanced spatial and temporal resolution of NDVI data for agricultural health in Saudi Arabia, computation of rates of illegal deforestation in Southern Peru, estimates of tropical forest carbon stocks based on data integration with active sensors, and estimates of glacial flow rates. We synthesize the potentially enormous research and scientific value of Planet's persistent monitoring capability, and discuss methods by which the data will be disseminated into the scientific community.

Methane, Ethane, and Nitrogen Stability on Titan

Science.gov (United States)

Hanley, J.; Grundy, W. M.; Thompson, G.; Dustrud, S.; Pearce, L.; Lindberg, G.; Roe, H. G.; Tegler, S.

2017-12-01

Many outer solar system bodies are likely to have a combination of methane, ethane and nitrogen. In particular the lakes of Titan are known to consist of these species. Understanding the past and current stability of these lakes requires characterizing the interactions of methane and ethane, along with nitrogen, as both liquids and ices. Our cryogenic laboratory setup allows us to explore ices down to 30 K through imaging, and transmission and Raman spectroscopy. Our recent work has shown that although methane and ethane have similar freezing points, when mixed they can remain liquid down to 72 K. Concurrently with the freezing point measurements we acquire transmission or Raman spectra of these mixtures to understand how the structural features change with concentration and temperature. Any mixing of these two species together will depress the freezing point of the lake below Titan's surface temperature, preventing them from freezing. We will present new results utilizing our recently acquired Raman spectrometer that allow us to explore both the liquid and solid phases of the ternary system of methane, ethane and nitrogen. In particular we will explore the effect of nitrogen on the eutectic of the methane-ethane system. At high pressure we find that the ternary creates two separate liquid phases. Through spectroscopy we determined the bottom layer to be nitrogen rich, and the top layer to be ethane rich. Identifying the eutectic, as well as understanding the liquidus and solidus points of combinations of these species, has implications for not only the lakes on the surface of Titan, but also for the evaporation/condensation/cloud cycle in the atmosphere, as well as the stability of these species on other outer solar system bodies. These results will help interpretation of future observational data, and guide current theoretical models.

Monitoring glacier albedo as a proxy to derive summer and annual surface mass balances from optical remote-sensing data

Science.gov (United States)

Davaze, Lucas; Rabatel, Antoine; Arnaud, Yves; Sirguey, Pascal; Six, Delphine; Letreguilly, Anne; Dumont, Marie

2018-01-01

Less than 0.25 % of the 250 000 glaciers inventoried in the Randolph Glacier Inventory (RGI V.5) are currently monitored with in situ measurements of surface mass balance. Increasing this archive is very challenging, especially using time-consuming methods based on in situ measurements, and complementary methods are required to quantify the surface mass balance of unmonitored glaciers. The current study relies on the so-called albedo method, based on the analysis of albedo maps retrieved from optical satellite imagery acquired since 2000 by the MODIS sensor, on board the TERRA satellite. Recent studies revealed substantial relationships between summer minimum glacier-wide surface albedo and annual surface mass balance, because this minimum surface albedo is directly related to the accumulation-area ratio and the equilibrium-line altitude. On the basis of 30 glaciers located in the French Alps where annual surface mass balance data are available, our study conducted on the period 2000-2015 confirms the robustness and reliability of the relationship between the summer minimum surface albedo and the annual surface mass balance. For the ablation season, the integrated summer surface albedo is significantly correlated with the summer surface mass balance of the six glaciers seasonally monitored. These results are promising to monitor both annual and summer glacier-wide surface mass balances of individual glaciers at a regional scale using optical satellite images. A sensitivity study on the computed cloud masks revealed a high confidence in the retrieved albedo maps, restricting the number of omission errors. Albedo retrieval artifacts have been detected for topographically incised glaciers, highlighting limitations in the shadow correction algorithm, although inter-annual comparisons are not affected by systematic errors.

Effects of local meteorology and aerosols on ozone and nitrogen dioxide retrievals from OMI and pandora spectrometers in Maryland, USA during DISCOVER-AQ 2011.

Science.gov (United States)

Reed, Andra J; Thompson, Anne M; Kollonige, Debra E; Martins, Douglas K; Tzortziou, Maria A; Herman, Jay R; Berkoff, Timothy A; Abuhassan, Nader K; Cede, Alexander