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Статті в журналах з теми "Legs nitraté":
1
Berkovich, Yu A., S. O. Smolianina, V. G. Smolianin, Ya V. Morozov, and I. G. Tarakanov. "TECHNOLOGY OF MINERAL NUTRITION AND ILLUMINATION OF CROPS IN A SPACE VEGETABLE GREENHOUSE." Aerospace and Environmental Medicine 55, no. 6 (2021): 68–74. http://dx.doi.org/10.21687/0233-528x-2021-55-6-68-74.
Анотація:
Dependence of Chinese cabbage productivity and nitrate content in eatable biomass on the ammonium and nitrate nitrogen ratio and red light fraction was studied in the context of space greenhouse Vitacycle-T design. Crops were illuminated by a lighting unit assembled of red and white light-emitting diodes (LEDs) producing the photosynthetic photon flux (PPF) of 400–430 µmol/(m2•с) with the ratio of red and white LEDs inputs between 0 and 1.5. The ammonium-nitrate nitrogen ratio in nutrient solutions with stabilized total nitrogen varied from 0 to 1. Under all tested light spectra the favorable range of ammonium nitrogen makes up 15 to 45 mg/L with the maximum of 25 ± 2 mg/L and total nitrogen at 120 mg/L. Ammonium nitrogen increase above 53–55 mg/L leads to crop inhibition. Concentration of nitrates in eatable biomass did not exceed the permissible levels established for leave vegetables irrespectively of the ammonium-nitrate nitrogen ratio and decreased monotonously as ammonium nitrogen was rising above 10 mg/L. According to calculation, the Vitacycle-T root-feeding design (cartages of granular mineral-rich ionite BIONA-312 and slow-release fertilizer Osmocote 14-14-14) is capable to control total nitrogen and ammonium-nitrate nitrogen ratio within the favorable range.
2
Makarov, Petr, Tatyana Makarova, Zoya Samoylenko, Natalya Gulakova, and Inessa Kravchenko. "PRODUCTIVITY AND QUALITY EVALUATION OF TARRAGON AND THYME GROWN UNDER ARTIFICIAL LIGHT." Vestnik of Kazan State Agrarian University 16, no. 4 (January 8, 2022): 24–29. http://dx.doi.org/10.12737/2073-0462-2022-24-29.
Анотація:
The research aimed at evaluation of productivity and quality of tarragon and thyme medicinal material was carried out on hydroponic installations during 2019-2020. The objects under study were Monarkh and Gudvin tarragon varieties as well as Medok and Zmeyka thyme varieties. The plants were grown in mineral cotton substratum. Fertikea Hydro complex fertiliser with microelements and calcium nitrate were used. The growing conditions: ambient temperature +22…+25℃, solution temperature +20℃, ambient humidity 55…65%. Experiment regimens: growing under white LEDs (luminous flux 8000 lm, color temperature 4000 K, PPF 165 mkmol/s/m2) and color LEDs (combination of red, blue and white LEDs (32:16:32), luminous flux 6573 lm, PPF 143 mkmol/s/m2), for 16-hour light regimen. We found that thyme grown on a vertical hydroponic system increase its biomass 2.0…3.5 times compared to the conventional growing. The highest productivity of Zmeyka thyme variety is reached under white light, while for both the tarragon varieties and Medok thyme variety it is reached under coloured LEDs. Chlorophyll-a content in green biomass is a little higher under coloured LEDs for Zmeyka thyme variety and Gudvin tarragon variety, while the reverse trend is observed for Monarkh tarragon variety. All the varieties show higher chlorophyll-b content under coloured LEDs. Combined chlorophyll-a and chlorophyll-b content increases under coloured LEDs for the thyme varieties and Gudvin tarragon variety. Monarkh tarragon variety shows the highest combined chlorophyll content under white LEDs. Carotenoid concentration in Medok thyme variety and Monarkh tarragon variety is higher under white LEDs and it is higher under color LEDs for the rest of the varieties. Flavonoids in the studied varieties accumulate statistically better (1.5…3.0 times) under white LEDs
3
Bian, Zhong-Hua, Rui-Feng Cheng, Qi-Chang Yang, Jun Wang, and Chungui Lu. "Continuous Light from Red, Blue, and Green Light-emitting Diodes Reduces Nitrate Content and Enhances Phytochemical Concentrations and Antioxidant Capacity in Lettuce." Journal of the American Society for Horticultural Science 141, no. 2 (March 2016): 186–95. http://dx.doi.org/10.21273/jashs.141.2.186.
Анотація:
Light-emitting diodes (LEDs) have shown great potential for plant growth and development, with higher luminous efficiency and more flexible and feasible spectral control compared with other artificial lighting. The combined effects of red and blue (RB) LED with or without green (G) LED light and white LED light on lettuce (Lactuca sativa L.) growth and physiology, including nitrate content, chlorophyll fluorescence, and phytochemical concentration before harvest, were investigated. Continuous light exposure at preharvest can effectively reduce nitrate accumulation and increase phytochemical concentrations in lettuce plants. Nitrate accumulation is dependent on the spectral composition and duration of treatment: lettuce exposed to continuous RB (with or without G) LED light with a photosynthetic photon flux (PPF) of 200 µmol·m−2·s−1 exhibited a remarkable decrease in nitrate content at 24 hour compared with white LED light treatment at the same PPF. In addition, RB LED light (R:B = 4:1) was more effective than white LED light at the same PPF in facilitating lettuce growth. Moreover, continuous LED light for 24 hours significantly enhanced free-radical scavenging activity and increased phenolic compound concentrations. We suggest that 24 hours continuous RB LED with G light exposure can be used to decrease nitrate content and enhance lettuce quality.
4
Ahmed, Asmaa Sayed, Arshad Abdulkhalq Yaseen, and Triska Dlshad Bakr. "Effect of Light-Emitting Diodes (LEDs) on Some Physical and Bioactive Compounds of ‘Iceberg’ Lettuce (Lactuca Sativa L.)." Acta Biologica Marisiensis 4, no. 1 (June 1, 2021): 21–30. http://dx.doi.org/10.2478/abmj-2021-0003.
Анотація:
Abstract The use of light-emitting diodes (LEDs) is a recent concerned application in the indoor crop system of the modern plant production. In our research, we evaluated the influence of four monochromic LED lights including 100% White (W), Yellow (Y), Red (R) and Blue (B) in comparison to solar lightening condition (GR) as a control. In this regard, some morphological characteristics and biochemical content of the common outdoor ‘Iceberg’ lettuce (Lactuca sativa L.) was measured. The results show that leaf length, leaf area and total head weight were significantly greater in the plants grown under B LED, while all the other physical parameters were significantly higher in the plants grown under GR environmental conditions. On the other hand, chlorophyll (Chl), carotenoids (Car), and nitrate content were also influenced by different light treatments. Plants grown under LED light treatment resulted in significantly higher chlorophyll content compared to the control. However, significantly greater carotenoid content was in the plants grown under GR condition. The highest total chlorophyll content was recorded under B and R LED, whereas the lowest was in the GR condition. The lowest nitrate content in the blade and petiole was recorded in the plants grown under Y LED, while the highest nitrate content was recorded in the GR. Based on our result, it is possible to grow and improve some quality parameters of common outdoor ‘iceberg’ lettuce under LED where the solar light is limited or unavailable. Thus, plants performed better under GR light conditions than monochromic LEDs; however, some LED lights could improve some quality parameters and biochemical contents in the ‘iceberg’ lettuce variety.
5
Kozel, N. V., M. S. Radyuk, T. V. Samovich, I. A. Dremuk, and L. S. Gabrielyan. "Protein accumulation and expression of the nitrate reductase gene in Spirulina platensiscells depending on the spectral composition of led radiation." Proceedings of the National Academy of Sciences of Belarus, Biological Series 64, no. 2 (May 18, 2019): 180–89. http://dx.doi.org/10.29235/1029-8940-2019-64-2-180-189.
Анотація:
The effect of LED lighting of different spectral composition on the productivity of Spirulina platensis, an accumulation of protein in alga cells and an expression of the nitrate reductase gene has been studied. It was shown that LED lighting with a predominance of the red component in the emission spectrum allows achieving 9–29 % higher alga productivity compared to using fluorescent lamp illumination. Illumination with single blue light resulted in significant (83 %) decrease in the productivity of Spirulina platensiswhich apparently was due to the absence of the yellow and red components in the illuminator spectral composition, which are most effectively absorbed by phycocyanin. A positive correlation between an increase in the productivity of alga and the accumulation of protein in its cells was found. So, by using an illuminator with red LEDs, the protein content increased by 21 % calculated per gram of dry weight and 47 % calculated per liter of suspension relative to the control. Analysis of the expression of the Nar gene encoding nitrate reductase in Spirulina platensiscells did not reveal a direct dependence between an increasing protein accumulation and an expression level of the Nar gene in the most promising in terms of biomass and protein yield sample of alga, growing under red LEDs. This indicates the crucial role of the photosynthetic activity of Spirulina platensiscells in increasing productivity and protein synthesis.
6
Khan, Khurshid Ahmed, Zhengnan Yan, and Dongxian He. "Impact of Light Intensity and Nitrogen of Nutrient Solution on Nitrate Content in Three Lettuce Cultivars Prior to Harvest." Journal of Agricultural Science 10, no. 6 (May 6, 2018): 99. http://dx.doi.org/10.5539/jas.v10n6p99.
Анотація:
Nitrate smoothly accumulates in leafy vegetables and poses serious health hazards if connected excessively in the human diet. The objective of this study was to improve the cultivation method of low nitrate lettuce grown in plant factory. A substantial decrease of nitrate content (NO3-) in three lettuce cultivars were subjected by short-term pre-harvest treatment combined with lowing nitrogen supply of nutrient solution to half concentration and high photosynthetic photon flux density (PPFD) by LED lighting. The lettuce (Lactuca sativa L. cv. Frill ice, Lvzhu, Ziwei) were hydroponically grown in full strength of nutrient solution based on Yamasaki formula up to harvest time within a controlled environment under two light sources using fluorescent lamps and LEDs. The results demonstrated that a subsequent 3-days treatment of additional PPFD from 250 µmol m-2 s-1 to 350 µmol m-2 s-1 from 18 days after transplanting and half concentrations of nitrogen (NO3--N) in nutrient solution which is composition to standard resulted in the decrease of nitrate content as compared to plants grown under initial PPFD and full concentration of NO3--Ncomposition. The gradual decrease in nitrate content was accompanied by an increased concentration of nutritionally carbohydrates. Another important indicator of nutritional quality such as vitamin C content exhibited some variation, fresh weight of cultivars in cv. Frill ice and Ziwei observed higher with fluorescent lamps and for cv. Lvzhu with LED treatment section followed by lowest nitrate content of fresh leaves, respectively. Further, presented results disclosed that to avoid high accumulation of nitrate in leafy vegetables, the strategy of lowering nitrogen supply and increasing light intensity prior to harvest benefiting growers and consumers by improving quality of the product also making it consumer friendly.
7
Yan, Zhengnan, Dongxian He, Genhua Niu, Qing Zhou, and Yinghua Qu. "Growth, Nutritional Quality, and Energy Use Efficiency of Hydroponic Lettuce as Influenced by Daily Light Integrals Exposed to White versus White Plus Red Light-emitting Diodes." HortScience 54, no. 10 (October 2019): 1737–44. http://dx.doi.org/10.21273/hortsci14236-19.
Анотація:
Few researchers examined different red light amounts added in white light-emitting diodes (LEDs) with varied daily light integrals (DLIs) for hydroponic lettuce (Lactuca sativa L.). In this study, effects of DLI and LED light quality (LQ) on growth, nutritional quality, and energy use efficiency of hydroponic lettuce were investigated in a plant factory with artificial lighting (PFAL). Hydroponic lettuce plants (cv. Ziwei) were grown for 20 days under 20 combinations of five levels of DLIs at 5.04, 7.56, 10.08, 12.60, and 15.12 mol·m−2·d−1 and four LQs: two kinds of white LEDs with red to blue ratio (R:B ratio) of 0.9 and 1.8, and two white LEDs plus red chips with R:B ratio of 2.7 and 3.6, respectively. Results showed that leaf and root weights and power consumption based on fresh and dry weights increased linearly with increasing DLI, and light and electrical energy use efficiency (LUE and EUE) decreased linearly as DLI increased. However, no statistically significant differences were found in leaf fresh and dry weights and nitrate and vitamin C contents between DLI at 12.60 and 15.12 mol·m−2·d−1. Also, no effects of LQ on leaf dry weight of hydroponic lettuce were observed at a DLI of 5.04 mol·m−2·d−1. White plus red LEDs with an R:B ratio of 2.7 resulted in higher leaf fresh weight than the two white LEDs. LUE increased by more than 20% when red light fraction increased from 24.2% to 48.6%. In summary, white plus red LEDs with an R:B ratio of 2.7 at DLI at 12.60 mol·m−2·d−1 were recommended for commercial hydroponic lettuce (cv. Ziwei) production in PFALs.
8
Heymich, Marie-Louise, Showmika Srirangan, and Monika Pischetsrieder. "Stability and Activity of the Antimicrobial Peptide Leg1 in Solution and on Meat and Its Optimized Generation from Chickpea Storage Protein." Foods 10, no. 6 (May 25, 2021): 1192. http://dx.doi.org/10.3390/foods10061192.
Анотація:
The antimicrobial peptide Leg1 (RIKTVTSFDLPALRFLKL) from chickpea legumin is active against spoilage bacteria, yeast, and mold. The present study tested its effectiveness under food storage conditions and examined options to obtain a food-grade agent. The minimum inhibitory concentration (MIC) of Leg1 against E. coli (62.5 µM) proved stable over seven days at 20 °C or 4 °C. It was not influenced by reduced pH (5.0 vs. 6.8), which is relevant in food such as meat. An incubation temperature of 20 °C vs. 37 °C reduced the MIC to 15.6/7.8 µM against E. coli/B. subtilis. With a minimum bactericidal concentration in meat of 125/15.6 µM against E. coli/B. subtilis, Leg1 is equivalently effective as nisin and 5000–82,000 times more active than sodium benzoate, potassium sorbate, or sodium nitrite. Replacing the counter-ion trifluoroacetate derived from peptide synthesis by the more natural alternatives acetate or chloride did not impair the activity of Leg1. As an alternative to chemical synthesis, an optimized protocol for chymotryptic hydrolysis was developed, increasing the yield from chickpea legumin by a factor of 30 compared to the standard procedure. The present results indicate that food-grade Leg1 could possibly be applicable for food preservation.
9
Hayat, S., and A. Ahmad. "Nitrate reductase activity and yield of Lens culinaris sprayed with 28-homobrassinolide." Acta Agronomica Hungarica 51, no. 4 (December 1, 2003): 381–87. http://dx.doi.org/10.1556/aagr.51.2003.4.2.
Анотація:
Thirty-day-old plants of Lens culinaris (L.) Medic. cv. Pusa-6 were sprayed with 10-10, 10-8 or 10-6 M aqueous solutions of 28-homobrassinolide (HBR). Root length and nodule number per plant decreased, whereas the leaf nitrate reductase activity (E.C. 1.6.6.1) at 60, 90 and 120 days after sowing and the seed yield at harvest increased significantly in plants sprayed with either concentration of HBR. The values increased at first with an increase in the concentration of HBR but decreased with a further increase above 10-8M, which proved best for improving seed production.
10
Ródenas-Torralba, Eva, Fábio R. P. Rocha, Boaventura F. Reis, Ángel Morales-Rubio, and Miguel de la Guardia. "Evaluation of a Multicommuted Flow System for Photometric Environmental Measurements." Journal of Automated Methods and Management in Chemistry 2006 (2006): 1–9. http://dx.doi.org/10.1155/jammc/2006/20384.
Анотація:
A portable flow analysis instrument is described for in situ photometric measurements. This system is based on light-emitting diodes (LEDs) and a photodiode detector, coupled to a multipumping flow system. The whole equipment presents dimensions of25 cm×22 cm×10 cm, weighs circa 3 kg, and costs 650 €. System performance was evaluated for different chemistries without changing hardware configuration for determinations of (i)Fe3+withSCN-, (ii) iodometric nitrite determination, (iii) phenol with sodium nitroprusside, and (iv) 1-naphthol-N-methylcarbamate (carbaryl) withp-aminophenol. The detection limits were estimated as 22, 60, 25, and 60 ngmL-1for iron, nitrite, phenol, and carbaryl at the 99.7% confidence level with RSD of 2.3, 1.0, 1.8, and 0.8%, respectively. Reagent and waste volumes were lower than those obtained by flow systems with continuous reagent addition. Sampling rates of 100, 110, 65, and 72 determinations per hour were achieved for iron, nitrite, phenol, and carbaryl determinations
Дисертації з теми "Legs nitraté":
1
Erostate, Mélanie. "Dynamique spatio-temporelle des flux naturels et anthropiques vers les hydrosystèmes littoraux tributaires des eaux souterraines : Investigations isotopiques et géochimiques pour la compréhension des interactions aquifères-lagune sur le site de Biguglia (Haute-Corse)." Thesis, Corte, 2020. http://hal-univ-corse.archives-ouvertes.fr/view_by_stamp.php?&action_todo=view&id.
Анотація:
L’anthropisation grandissante des bassins versants côtiers représente une menace importante pour les eaux souterraines et les écosystèmes qui en dépendent, alors appelés « écosystèmes tributaires des eaux souterraines ». A l’image de l’hydrosystème de Biguglia (Corse), l’urbanisation rapide et désorganisée ainsi que les activités industrielles et agricoles développées sur la plaine de la Marana sont autant de sources de dégradation des eaux souterraines. Cette ressource, pourtant stratégique et utilisée pour l’alimentation en eau potable de la région bastiaise, présente aujourd’hui les marqueurs d’une contamination multiple et diffuse sur l’ensemble de la plaine. En plus d’être problématique pour les besoins en eau humains, la dégradation qualitative des eaux souterraines de l’aquifère de la Marana, constitue également une menace pour l’écosystème fragile de la lagune de Biguglia et la pérennité des services écosystémiques qu’il prodigue. Dans ce contexte de pressions croissantes, la connaissance approfondie du fonctionnement de l’hydrosystème de Biguglia s’impose comme un élément essentiel pour garantir une gestion durable de la ressource en eau. Dans ce but, une approche multi-traceurs géochimiques et isotopiques a été développée afin notamment de mieux contraindre l’état de la ressource, les conditions hydrodynamiques et la nature des interactions aquifères-rivières-lagune. L’étude des isotopes stables de la molécule d’eau (18O, 2H) a mis en évidence la complexité de la recharge. L’aquifère de la Marana bénéficie d’une recharge autochtone par l’infiltration directe des précipitations sur la plaine et d’une recharge allochtone par les précipitations en provenance des contreforts schisteux. A ces mécanismes, s’ajoute également la recharge prodiguée par l’infiltration des eaux du Bevincu et du Golu et la contribution latérale des eaux en provenance des contreforts schisteux de la Corse alpine. Le modèle de mélange développé (18O, Cl- et HCO3-) a permis une estimation semi-quantitative des mélanges. Il démontre la complexité du fonctionnement de l’aquifère, avec une différence notable de la contribution des contreforts schisteux en fonction de la localisation et de la profondeur de la ressource. Il apparaît également de manière claire que la lagune de Biguglia est partiellement tributaire des eaux souterraines. La plaine de la Marana est sujette à une dégradation qualitative liée à la présence excessive de nitrates (NO3-) et de micropolluants organiques. D’après les isotopes du NO3- (15N-NO3-, 18O-NO3-) et du Bore (11B), les principales sources d’azote sont le sol et les eaux usées. La corrélation entre concentrations en NO3- et temps de résidence des eaux (3H et CFCs) a mis en avant la capacité de stockage et d’archivage des eaux souterraines de l’aquifère de la Marana. Mise au regard de l’évolution de l’occupation des sols sur la plaine, la modification progressive des sources azotées enregistrée dans l’aquifère a permis de retracer la trajectoire socio-environnementale de l’hydrosystème de Biguglia. L’état contemporain dégradé de la ressource découle en grande partie de l’héritage des pollutions liées aux activités humaines historiques. Le modèle conceptuel élaboré grâce à ces travaux apporte de nouveaux éléments de compréhension qui pourront aider à l’instauration de stratégies de gestion pertinentes, assurant la pérennité future des ressources en eau et des services écosystémiques qui en dépendentThe exacerbated anthropization of coastal hydrosystems poses a significant threat to groundwater and ecosystems that depend on it, then called "groundwater-dependent ecosystems". Like the Biguglia hydrosystem (Corsica, France), rapid and disorganized urbanization, as well as industrial and agricultural activities developed on the Marana plain are major sources of groundwater degradation. This strategic resource, used for the drinking water supply of the Bastia urban area, presents the markers of multiple and diffuse contaminations. In addition to being problematic for human water needs, the groundwater qualitative degradation of the Marana aquifer also constitutes a threat to the fragile ecosystem of the Biguglia lagoon and the sustainability of the ecosystem services it provides. In this context of increasing pressures, a strong knowledge of the Biguglia hydrosystem behavior is essential to ensure sustainable management of water resources. To this end, a multi-tracer geochemical and isotopic approach has been developed in order to better constrain the state of the groundwater resource, the hydrodynamic conditions and the nature of aquifer-river-lagoon interactions. The study of the stable isotopes of the water molecule (18O, 2H) has highlighted the recharge complexity. The Marana aquifer benefits from an indigenous recharge through direct infiltration of precipitation on the plain and an allochthonous recharge through precipitation from the schistous reliefs. The infiltration of river water from the Bevincu and Golu rivers and the lateral contribution of water from the schistous reliefs also contribute to the aquifer recharge. The developed mixing model (18O, Cl- and HCO3-) allowed a semi-quantitative estimation of the mixing processes. It demonstrates the complex aquifer behavior, with a significant difference in the contribution of schistous groundwater depending on the location and depth of the resource. It is also clear that the Biguglia lagoon is partially dependent on groundwater. The Marana plain is subject to qualitative degradation due to the excessive presence of nitrates (NO3-) and organic micropollutants. According to the NO3- (15N-NO3-, 18O-NO3-) and Boron (11B) isotopes, the main sources of nitrogen are soil and wastewater. The correlation between NO3- concentrations and water residence time (3H and CFCs) highlighted the storage and the groundwater archiving capacity. With regard to the evolution of land use, the progressive modification of the nitrogen sources recorded in the aquifer made it possible to trace the socio-environmental trajectory of the Biguglia hydrosystem. The contemporary degraded state of the resource mainly results from the pollution legacy linked to historical human activities. The conceptual model developed provides new elements that can help towards the implementation of relevant management strategies, to ensure the sustainability of water resources and associated ecosystem services
2
Weiss, Nathalie. "La pollution des eaux par les nitrates : cas particulier de la région charentaise." Bordeaux 2, 1994. http://www.theses.fr/1994BOR2P017.
3
Machado, Franck. "Reactions photochimiques induites sur les composes phenoliques par excitation des ions nitrate et nitrite en solution aqueuse." Clermont-Ferrand 2, 1994. http://www.theses.fr/1994CLF21610.
Анотація:
L'excitation photochimique des ions nitrite et nitrate en presence de composes phenoliques peut induire des oxydations, des nitrations et des nitrosations. Les reactions d'oxydation se produisent quel que soit le substituant et peuvent etre attribuees aux radicaux hydroxyle formes lors de la photolyse des ions. Les reactions de nitration et de nitrosation sont defavorisees par les substituants electro-attracteurs. Quand les ions nitrite sont excites en presence de phenol ou de resorcinol, une nitrosation en para est observee, qui peut etre attribuee aux oxydes d'azote formes lors de la photolyse des ions nitrite. Cette reaction est favorisee par l'augmentation de la concentration en ions nitrite. L'influence de l'oxygene est expliquee par la competition entre deux mecanismes, l'un faisant intervenir n#2o#3, et l'autre l'adduit radicalaire phenol. . . No#2. Cette nitrosation ne se produit pas avec le pyrocatechol et l'hydroquinone. Avec ces substrats, une reaction de nitration est observee, mais seulement en presence d'oxygene. On observe des reactions plus complexes par excitation des ions nitrate en presence de phenol ou de resorcinol. La formation de derives nitres et nitroses qui est observee est attribuee aux oxydes d'azote no#2 et n#2o#4. Avec le pyrocatechol et l'hydroquinone, il n'y a pas de nitrosation et la nitration est defavorisee par la presence d'oxygene. Dans les conditions environnementales, la nitration et la nitrosation par excitation des ions nitrite sont tres improbables. Avec les ions nitrate, l'importance des reactions de nitration et de nitrosation depend de la concentration en composes phenoliques et du ph de la solution
4
Pham, Hoai Nam. "Estimation de nitrate, nitrite et autres composés à partir de spectres ultraviolets, pour l'agroalimentaire et les eaux résiduaires." Compiègne, 2008. http://www.theses.fr/2008COMP1762.
Анотація:
Les teneurs en nitrates, nitrites et d'autres ions peuvent être estimées par spectrophotométrie UV dans les eaux usées et dans les légumes pour le contrôle de procédé, ainsi que pour la surveillance in situ. La méthode est basée sur l'identification spectrale: le spectre UV d'un échantillon est considéré comme une combinaison linéaire de spectres de référence. L'identification de spectres UV de solutions aqueuses peut discriminer le nitrite du nitrate, dans la gamme de 0,5 à 5 mg-N/L, et ce même en présence de chlorure, jusqu'à 100 mg/L et de bicarbonate, jusqu'à 200 mg/L. Les essais dans différentes conditions réelles au SIAAP montrent que cette méthode peut être utilisée pour la surveillance en ligne dans la station d'épuration traitant les eaux de Paris. Plusieurs légumes frais ainsi que les épinards congelés ont été testés. La teneur en nitrates varie de 377 à 3240 mg/kg de légumes frais, et de 545 à 1190 mg/kg d'épinards surgelés. Les ajouts dosés de nitrate montrent l'exactitude de la méthode, avec des récupérations de 91 à 99 % du nitrate ajouté. Les essais de validation effectués sur un site industriel ont montré le potentiel de la méthode d'identification spectrale. Cette méthode n'exige presque pas de consommable, est très rapide et quantitative, avec une maintenance facile et peu onéreuse. Le logiciel d'identification UV-Pro utilisé a toujours montré des résultats analogues à ceux obtenus par PLS ou PCR, il est basé sur des méthodes de résolution analogues. Les perspectives de ce travail sont l'utilisation des méthodes d'identification non linéaires et l'ajout d'autres méthodes de détection pour élargir les potentialités de la spectrophotométrie UVContents of nitrate, nitrite and some others ions can be estimated by UV spectrophotometry in wastewater also in vegetables for processing control as well as for in-situ monitoring. The method is based on the spectral identification: UV spectrum of a sample is considered as a linear combination of absorption spectra, named reference spectra. Mathematical identification of UV spectra can discriminate nitrite from nitrate, in the range of 0. 5 to 5 mg-N/L, even in presence of up to 100 mg/L chloride and up to 200 mg/L bicarbonate. The tests in different real conditions show that this method can be used for on-line monitoring in the Wastewater Treatment Plant of Paris. Several fresh vegetables as well as frozen spinaches have been tested. The nitrate content varied from 377 to 3240 mg/kg of fresh vegetables, and 545 to 1190 mg/kg of frozen spinach. The recovery of added nitrate ranged from 91 to 99%. The validation tests carried out in one industry showed the potentiality of the method of spectral identification. This method does not require almost any consumable, is quantitative and very fast reading with easy and low maintenance. The UV-Pro software identification used during this thesis has always shown similar results to those obtained by PLS or PCR, it is based on considerations and methods similar resolution. The prospects of this work will be the use of non-linear methods of identification and the use of complementary methods to expand the potential of UV spectrophotometry
5
Soropogui, Koïkoï. "Mise au point de capteurs économiques pour la détermination électroanalytique des ions nitrate ou nitrite dans les eaux naturelles." Lyon 1, 2007. http://www.theses.fr/2007LYO10268.
Анотація:
Les ions nitrate et les ions nitrite sont des composés chimiques présents naturellement dans l'environnement. Normalement leur taux dans les eaux superficielles et dans les eaux souterraines est faible. Il peut cependant atteindre des niveaux élevés suite à certaines activités humaines et représenter un risque sanitaire et environnemental. La mise au point de moyens peu coûteux permettant de surveiller le taux des ions nitrate et nitrite dans les eaux de surface est une nécessité pour la préservation de l'environnement et de la santé humaine. Face à cette nécessité nous nous sommes intéressés à l’étude de matériaux relativement facile à mettre en oeuvre et d’un coût modéré. Pour les ions nitrate, nous nous sommes intéressés au cuivre, au palladium et aux films de cuivre sur disque de palladium. Ces électrodes ont été testées sur des eaux synthétiques et des eaux naturelles de surface. Les réponses de ces matériaux, obtenues par chronoampérométrie, lors des mesures en continu des ions nitrate dans ces milieux montrent que le disque de palladium est le matériau le mieux adapté à ce type de mesure. Le palladium est donc choisi pour la mise en place d’un mini système à trois électrodes solides enchâssées dans une résine. Les tests de surveillance des niveaux de pollutions en ions nitrate d’une eau naturelle circulant dans une rivière artificielle confirme que ce mini système peut servir de capteur de surveillance des niveaux d’ions nitrate dans les eaux naturelles de surface. Pour la mesure des ions nitrite, le matériau étudié est un film de cobalt électrodéposé sur disque de cuivre. Il est montré dans ce travail que ce matériau peut servir d’électrode pour la mesure par ajouts dosés des ions nitrite dans des échantillons d’eau naturelle. Cette électrode atteint une limite de détection de 9. 10-3 ppm soit 2. 10-7 mol/L d’ions nitrite sans interférence des ions nitrate présents en quantité importante dans l’eau naturelle. Pour les ions nitrate et les ions nitrite, il est également montré que la présence des ions hydrogénocarbonate, sulfate, chlorure, calcium, magnésium n’empêche pas leur détection à l’aide des capteurs, aux teneurs usuelles rencontrées dans les eaux souterraines et de surface
6
Lefebvre, Hervé. "Etudes thermodynamique et cinétique de la corrosion du fer par les mélanges de nitrate et de nitrite de sodium fondus." Grenoble 2 : ANRT, 1988. http://catalogue.bnf.fr/ark:/12148/cb37615108t.
7
Lefebvre, Hervé. "Etudes thermodynamique et cinetique de la corrosion du fer par les melanges de nitrate et de nitrite de sodium fondus." Paris 6, 1988. http://www.theses.fr/1988PA066353.
Анотація:
Caracterisation des oxydes formes lors de la corrosion du fer dans les nitrates alcalins et leurs melanges avec les nitrites et etablissement du diagramme potentiel acidite du fer dans ces milieux en fonction de la temperature (420-520**(o)c). Etude par spectroscopie d'impedance du pouvoir passivant du ferrate nafeo::(2). Modelisation du processus de corrosion
8
Bourgeois, Ilann. "Dépôt des nitrates atmosphériques sur les prairies subalpines du Lautaret." Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAV059/document.
Анотація:
L’accroissement des dépôts de nitrate atmosphérique (NO3-atm) sur les bassins versants d’altitude, limités en ressources, entraîne des changements nets de disponibilité d’azote. Ces apports modifient la diversité biologique (végétation, plantes), les processus des sols liés à l’azote et conduisent à l’eutrophisation des cours d’eau. A terme, l’impact sur les populations humaines se traduira par la perte d’importants services fournis par ces écosystèmes (alimentation en eau, qualité du fourrage, contrôle de l’érosion, biodiversité). Si les effets des dépôts de NO3-atm sur les bassins versants pauvres en azote sont maintenant bien documentés, il n’en reste pas moins à comprendre les processus régissant la rétention de NO3-atm dans les écosystèmes de montagne. Pour ce faire, la variabilité spatio-temporelle de la répartition du NO3-atm dans tous les compartiments subalpins est ici étudiée en utilisant un traceur multi-isotopique (17O, 18O, 15N) du NO3-. L’importante proportion de NO3-atm dans les cours d’eau de montagne, tout au long de l’année et plus particulièrement à la fonte des neiges, laisse à penser que les bassins versants sont cinétiquement saturés en azote. La composition isotopique du NO3- dans les eaux de surface illustre la transformation rapide de l’ammonium de la neige et confirme que la fonte des neiges est une période cruciale du cycle de l’azote dans les montagnes enneigées. La proportion de NO3-atm dans les sols varie, quant à elle, en fonction du type d’occupation des sols et des propriétés biotiques et abiotiques afférentes. Le suivi de la végétation a montré une forte teneur en NO3-atm dans les tissus, par assimilation racinaire et foliaire. Ces avancées scientifiques permettront, à terme, de mieux comprendre comment les dépôts de NO3-atm affectent l’environnementIncreasing rates of atmospheric nitrate (NO3-atm) deposition in nutrients poor mountainous regions have led to critical changes in nitrogen (N) availability, with consequences on biodiversity (plants, microbes), soils N turnover, and water nutrients status. This will ultimately affect human populations through the loss of critical ecosystem services (e.g., provision of clean freshwater, erosion control, biodiversity). If the impacts of NO3-atm deposition to N-limited basins are now well documented, little is known about the processes driving NO3-atm retention in subalpine ecosystems. In this context, new tools are necessary to better understand the fate of NO3-atm in mountains and to predict the mid and long-term ecological consequences of increasing NO3-atm deposition. This work uses a high-resolution multi-isotopic technique combining 17O, 18O and 15N signatures of NO3- in the different subalpine compartments to understand the temporal and spatial evolution of NO3-atm partitioning in a subalpine watershed of the French Alps. Subalpine streams elevated year-round exports of NO3-atm suggest that the watersheds are kinetically N saturated, especially after snowmelt. The isotopic composition of NO3- in freshwaters also points at the rapid processing of snow ammonium, confirming that snowmelt is “hot moment” for the N cycle in seasonally snow-covered catchments. The monitoring of soils reveals varying NO3-atm proportions depending on the land management treatments and implied biotic and abiotic characteristics. Two dominant subalpine plants showed high proportions of NO3-atm in organs acquired by both root and foliar uptake. These scientific breakthroughs will ultimately lead to a better understanding of how NO3-atm deposition affects the environment
9
Wirth, Judith. "La régulation des transporteurs de nitrate au niveau ARN et protéines dans les racines de Arabidopsis thaliana." Montpellier, ENSA, 2006. http://www.theses.fr/2006ENSA0015.
Анотація:
AtNRT1. 1 et AtNRT2. 1 sont deux gènes codants pour les principaux transporteurs racinaires de NO3- chez Arabidopsis thaliana. Au niveau des ARNm il a été montré qu'ils sont tous les deux induits par la lumière et les sucres et que AtNRT2. 1 est réprimé par les métabolites azotés issus de l'assimilation de NO3-. Ces régulations au niveau moléculaire sont étroitement corrélées avec celles observées au niveau de l'absorption de NO3-. Dans ce contexte les objectifs de la thèse étaient (i) de déterminer dans quelle partie du métabolisme carboné se trouve le signal inducteur responsable de la régulation de AtNRT1. 1 et AtNRT2. 1 par la lumière et les sucres au niveau des ARNm et (ii) d'étudier au niveau protéique la localisation et la régulation de AtNRT2. 1 afin de mettre en évidence l'existence d'éventuelles régulations post-traductionelles. Le dosage des métabolites carbonés en réponse à différents traitements (cycle jour/nuit, apport de saccharose et d'autres métabolites carbonés) a permis de mettre en évidence une forte corrélation entre la concentration en glucose-6-phosphate (G6P) dans les racines et l'expression de AtNRT1. 1 et AtNRT2. 1. Le G6P est à la fois un intermédiaire de la glycolyse et le point d'entrée de la voie des pentoses phosphates qui, dans les racines, fournit le pouvoir réducteur nécessaire à l'assimilation de NO3-. Lorsque la voie des pentoses phosphates est inhibée, l'induction par les sucres des deux transporteurs de NO3- est fortement réduite. Ceci suggère que la voie de signalisation impliquée dans la régulation de AtNRT2. 1 et AtNRT1. 1 fait appel à un mécanisme original impliquant la voie des pentoses phosphates. Au niveau protéique, l'obtention de plantes transgéniques exprimant une protéine fusion AtNRT2. 1::GFP et d'un anticorps spécifique contre AtNRT2. 1 ont permis de localiser ce transporteur dans la membrane plasmique et le reticulum endoplasmique des cellules de l'épiderme et du cortex des racines, à l'exception des pointes racinaires ou AtNRT2. 1 est absent. L'étude en Western blots et ELISA de l'abondance de la protéine en réponse essentiellement à la lumière et aux sucres mais aussi aux métabolites azotés ont permis de montrer (i) que AtNRT2. 1 est présent sous deux formes distinctes dans la membrane plasmique : la protéine isolée et celle incorporée dans un complexe de haut poids moléculaire et (ii) que contrairement aux ARNm et à l'absorption de NO3-, la quantité de protéine AtNRT2. 1 ainsi que sa localisation sur la membrane plasmique varient peu ce qui suggère l’existence de régulations post-traductionnelles. L'hypothèse formulée à l'issue de ce travail est que la forme complexée de AtNRT2. 1 est impliquée dans le transport de NO3- et qu'elle correspond à une association avec la protéine AtNRT3. 1 de type NAR2 qui chez Arabidopsis est nécessaire à la fonction de transport de NO3-. De plus une des régulations post-traductionelles permettant l'association de AtNRT2. 1 sous forme de complexe pourrait correspondre au clivage de la partie C-terminale de NRT2. 1. L’existence de ce clivage a été mise en évidence grâce aux plantes transgéniques exprimant une fusion traductionnelle NRT2. 1 ::GFP en Cter (apparition d’une forme tronquée de NRT2. 1 et de GFP libre).
10
BENVENUTI, PASCAL. "Problemes lies a l'evolution des teneurs en nitrates dans les eaux souterraines." Strasbourg 1, 1989. http://www.theses.fr/1989STR15009.
Книги з теми "Legs nitraté":
1
Great Britain. Scottish Office Environment Department., ed. Criteria and procedures for identifying sensitive areas and less sensitive areas (Urban waste water treatment directive) and polluted waters(Nitrates directive) in Scotland: Consultation paper. [Edinburgh]: Scottish Office Environment Department, 1992.
Частини книг з теми "Legs nitraté":
1
Raven, J. A., and G. D. Farquhar. "The Greater 13C Natural Abundance in Nitrate-Grown than in Ammonium-Grown Ricinus Communis is Mainly a Function of the Lower Ratio of CO2-Transport Limitation to Biochemical Limitation of Photosynthesis in Nitrate-Grown Plants, with their Higher Organic Anion Content as a Less Significant Factor." In Inorganic Nitrogen in Plants and Microorganisms, 121–23. Berlin, Heidelberg: Springer Berlin Heidelberg, 1990. http://dx.doi.org/10.1007/978-3-642-75812-6_18.
2
Calvert, Jack, Abdelwahid Mellouki, John Orlando, Michael Pilling, and Timothy Wallington. "Rate Coefficients and Mechanisms for the Atmospheric Oxidation of the Aldehydes." In Mechanisms of Atmospheric Oxidation of the Oxygenates. Oxford University Press, 2011. http://dx.doi.org/10.1093/oso/9780199767076.003.0007.
Анотація:
Aldehydes are emitted from a variety of anthropogenic sources associated with natural gas and petroleum combustion (for examples, see tables I-C-2 and I-C-3). Winer et al. (1992) have discussed direct emissions of aldehydes from biogenic sources. They are also important intermediates in the oxidation of directly emitted organic compounds. For example, formaldehyde, CH2O formed in the reaction of CH3O with O2 . . . CH3O + O2 → CH2O + HO2 . . . CH3O is formed in the oxidation of methane, and a number of other compounds. There are also many other sources of CH2O; for example, the Leeds University’s Master Chemical Mechanism (MCM) lists a total of ∼ 140 CH2O precursors: http://mcm.leeds.ac.uk/MCM/. Aldehydes with saturated hydrocarbon chains (termed alkanals or acyclic aldehydes) react mainly with OH during the day and with NO3 at night. The aldehydic C—H bond is weaker than those in the hydrocarbon chain; and, certainly for the shorter carbon chain species, abstraction by both OH and NO3 occurs primarily at the aldehydic center to form an acyl radical which reacts rapidly with O2 to form an acylperoxy radical, e.g., . . . CH3CHO + OH → CH3CO + H2O . . . . . . CH3CO + O2 → CH3C(O)O2 . . . An important reaction of the acylperoxy radical is with NO2 to form an acylperoxy nitrate. In the example shown, the oxidation of acetaldehyde gives acetyl peroxy radicals which can react with NO2 to form peroxyacetyl nitrate, CH3C(O)O2NO2, generally known as PAN: . . . CH3C(O)O2 + NO2 → CH3C(O)O2NO2 . . . Peroxyacyl nitrates dissociate quite quickly at 298 K, to regenerate peroxyacyl radicals. For example, PAN has a lifetime of about 50 min. The lifetime increases rapidly at the lower temperatures experienced at higher altitudes and is several months at the temperatures (∼ 250 K) of the upper troposphere. This long lifetime provides a mechanism for the transport of NOx from polluted areas to less polluted areas, by transfer of peroxyacyl nitrates from the boundary layer to the free troposphere; subsequent subsidence can return them to the boundary layer where they dissociate at the higher temperatures encountered there. The atmospheric reactions of the nitrates are discussed in detail in chapters VIII and IX.
3
Kirchman, David L. "Reviving Dead Zones." In Dead Zones, 154–72. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780197520376.003.0011.
Анотація:
Oxygen has returned to some dead zones, but many problems remain. As this chapter explains, nutrient input from agriculture in some regions has decreased because farmers use buffer zones, cover crops, and precision agriculture. But voluntary efforts to minimize nutrient pollution aren’t enough. In Iowa, the Des Moines Water Works, led by a charismatic CEO, Bill Stowe, unsuccessfully sued to reduce nitrate leaching from local farms. The value of government action has been demonstrated in Denmark, whereas its absence has led to many environmental problems in China. The chapter argues that one solution is tied to human health and climate change: our diet. Eating less, especially eating less red meat, would be better for our health, and it would reduce nutrient pollution and abate climate change. Agriculture accounts for nearly a third of all greenhouse gas emissions. The chapter ends by suggesting that the successful bans against DDT and phosphorus detergents are among the reasons to be optimistic about solving the dead-zone problem.
4
Lelieveld, Jos. "Air Pollution and Climate." In The Physical Geography of the Mediterranean. Oxford University Press, 2009. http://dx.doi.org/10.1093/oso/9780199268030.003.0038.
Анотація:
It has long been known that atmospheric pollutants can be hazardous to human health and ecosystems. This includes effects from episodic peak levels as well as the long-term exposure to relatively moderate concentration enhancements. Environmental issues related to air pollution include acidification, mostly by the strong acids from sulphur and nitrogen oxides, eutrophication by the deposition of reactive nitrogen compounds, the reduction of air quality by photo-oxidants and particulate matter, and the radiative forcing of climate by increasing greenhouse gases and by aerosol particles. Many air pollutants are photochemically formed within the atmosphere from emissions by traffic, energy generation, industry, the burning of wastes, and forest fires. The Mediterranean basin in summer is largely cloudfree, and the relatively intense solar radiation promotes the photochemical formation of ozone (O3) and peroxyacetyl nitrate (PAN); O3 being health hazardous at levels in excess of about 100 μg/m3. Ozone is formed in the lower atmosphere as a by-product in the oxidation of reactive carbon compounds such as carbon monoxide (CO) and non-methane volatile organic compounds (NMVOC), catalysed by nitrogen oxides (NOx ≡ NO + NO2). In summer, notably the period from June to August, transport pathways of air pollution near the earth’s surface are typically dominated by northerly winds, carrying photo-oxidants and aerosol particles from Europe into the Mediterranean basin. Aerosol particles with a diameter of less than ∼10 μm (PM10) can have adverse health effects at a concentration of about 30 μg/m3 or higher. The fine mode particles (<2 μm diameter) are mostly composed of sulphates, nitrates, and particulate organic matter, whereas the coarse mode particles (≥2 μm) often contain substantial amounts of sea salt, Saharan dust (Chapter 14), and other mineral components. The aerosols can form widespread hazes that scatter and absorb solar radiation, thus reducing downward energy transfer and surface heating. Increased aerosol scattering causes a negative radiative forcing of climate (cooling tendency), to be weighted against the positive radiative forcing (warming tendency) by increasing greenhouse gases such as carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), halocarbons, and tropospheric ozone (IPCC 2001).
Тези доповідей конференцій з теми "Legs nitraté":
1
Bradshaw, Robert W., Joseph G. Cordaro, and Nathan P. Siegel. "Molten Nitrate Salt Development for Thermal Energy Storage in Parabolic Trough Solar Power Systems." In ASME 2009 3rd International Conference on Energy Sustainability collocated with the Heat Transfer and InterPACK09 Conferences. ASMEDC, 2009. http://dx.doi.org/10.1115/es2009-90140.
Анотація:
Multi-component molten salts have been formulated recently that may enhance thermal energy storage for parabolic trough solar power plants. This paper presents further developments regarding molten salt mixtures consisting of common alkali nitrates and either alkaline earth nitrates or alkali nitrite salts that have advantageous properties for applications as heat transfer fluids in parabolic trough systems. We report results for formulations of inorganic molten salt mixtures that display freeze-onset temperatures below 100°C. In addition to phasechange behavior, several properties of these molten salts that significantly affect their suitability as thermal energy storage fluids were evaluated, including chemical stability and viscosity. The nitrate-based molten salts have demonstrated chemical stability in the presence of air up to 500°C. The capability to operate at temperatures up to 500°C may allow an increase in maximum temperature operating capability vs. organic fluids in existing trough systems and will enable increased power cycle efficiency. Experimental measurements of viscosity were performed from near the freeze-onset temperature to about 200°C. Viscosities can exceed 100 cP near the freezing temperature but are 4 to 5 cP in the anticipated operating temperature range. Experimental measurements of density, thermal conductivity and heat capacity are in progress and will be reported at the meeting. Corrosion tests were conducted for several thousand hours at 500°C with stainless steels and at 350°C for carbon and chromium-molybdenum steels. Examination of the specimens demonstrated good compatibility of these materials with the molten nitrate salt mixtures. Laboratory studies were conducted to identify mixtures of nitrate and nitrite (NO2−) salts as additional candidates for a low-melting heat transfer fluid. Mixtures in which the cations were potassium, sodium and lithium, in various proportions, demonstrated freezing points as low as 70°C for a particular nitrate/nitrite anion composition. Development has emphasized mixtures that minimize lithium content in order to reduce the cost as the lithium salt is the most expensive constituent. Work is in progress to explore the phase diagram of the 1:1 mol ratio of nitrate/nitrite and to evaluate physical properties such as viscosity, density and thermal conductivity. Results to date indicate that the viscosity of these mixtures is considerably less than nitrate-only melts, which necessarily contain calcium cations to suppress freezing to similarly low temperatures.
2
ŽIBIENĖ, Gražina, and Alvydas ŽIBAS. "WATER QUALITY AND WASTE CONTAMINATION STUDY IN CATFISH REARING RECIRCULATING AQUACULTURE SYSTEM." In RURAL DEVELOPMENT. Aleksandras Stulginskis University, 2018. http://dx.doi.org/10.15544/rd.2017.015.
Анотація:
In this article we analyse catfish rearing conditions in recirculating aquaculture systems (RAS). Based on research, performed by scientists from different countries, we evaluated optimal water parameter values for catfish rearing. African catfish growing process and with it associated factors were researched in JC ,,Šamas“. The amount of dissolved oxygen (on average 4,53 mg/l) in the rearing basin is adequate for the catfish to feel comfortable and for biomass growth. Water temperature only varies slightly – the average water temperature is 23,30C. The ideal pH for rearing fish in RAS is 7.0. Many aquaculture species continue to feel comfortable in pH boundaries of 6.5-8.5. In the samples, taken from catfish rearing system, the pH varied from 5.58 to 6.63. Such acidic water decreases the effectiveness of biological filter, but also decreases the toxic effect of excreted ammonia on the fish. Only a small amount of suspended solid is present in the samples, which means that they are being removed properly. The average amount of ammonia nitrogen in the water basins in analysed catfish rearing systems is 1,171 mg/l. The analysed water samples presented an average nitrite amount of 0,974 mg/l. The recommended amount of nitrites for catfish is less than 0.5 mg/l. The analysed samples presented relatively high nitrate values – from 412 to 495 mg/l. In order to decrease the concentration of accumulated nitrates it is required to change no less than 10% of total system water volume every day. The index of consumed biochemical oxygen corresponds to the requirements for water quality in RAS
3
Kim, Jungyoon, Qingyuan Liu, and Tianhong Cui. "Solution-Gated Ion-Sensitive Field Effect Transistor With Polymer Selective Membrane for Nitrate Detection." In ASME 2018 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/imece2018-87918.
Анотація:
In the paper, we fabricated a solution-gated ion-sensitive field effect transistor (IS-FET) and synthesized a selective membrane for the selective detection of nitrate. For sensor response, the level of Dirac point is measured to check the amount of nitrate in the water. Nitrate selective membrane is coated on graphene using a spin-coating method. The IS-FET is tested with four different ion solutions including chloride, sulfate, phosphate and nitrate at four different concentrations (0.1, 1, 10, 100 ppm). The Dirac point shift from −0.56 V to −0.36 V as increasing the concentration. The detection limit is 0.1 ppm, and the response time is less than 1 min.
4
He, Yue, Shenglong Zhang, Ziqian Dong, and Fang Li. "Conductive Polymer-Based Sensor for Soil Nutrient Detection." In ASME 2020 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/imece2020-24217.
Анотація:
Abstract To increase the production of crops, chemical fertilizers are used in crop fields. However, underuse or overuse cannot increase crop yields but even decrease them and cause severe environmental problems. Thus, the detection and monitoring of chemical concentration are increasingly important. To build up and monitor a data-based system for a large area, such a method is costly and time-consuming. In this research, we developed a conductive polymer-based sensor to detect nitrate concentrations in soil water. Conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) was used as our sensing material. To increase its conductivity, we used the vacuum phase polymerization method to achieve a high conductive and stable polymer film. The conductivity of the polymer film is 500 S/cm. Our results have demonstrated that the conductive polymer-based sensors have high sensitivity to nitrate solution. The response to 1000 ppm nitrate solution is 47.2% (Response = (Initrate - IDIwate) / IDIwater). The sensors can detect nitrate range from 1ppm to 1000 ppm. The response time is less than 1 minute. This impedance-based sensor will eventually be integrated with the surface acoustic wave sensors, combined with an antenna and a GPR unit for low maintenance, autonomous, and in-situ soil nutrient sensing.
5
Asahi, Toshimasa, Toshimasa Asahi, Kazuhiko Ichimi, Kazuhiko Ichimi, Kuninao Tada, and Kuninao Tada. "NUTRIENT DYNAMICS IN EELGRASS (ZOSTERA MARINA) MEADOW AND THE VARIATION OF NUTRIENT CONTENTS OF EELGRASS." In Managing risks to coastal regions and communities in a changing world. Academus Publishing, 2017. http://dx.doi.org/10.21610/conferencearticle_58b4316623b72.
Анотація:
Nutrient dynamics in seagrass beds and nutrient demands of seagrass biomass are not clear, although nutrient uptake of seagrass has been experimentally studied in the laboratory. We conducted the field observations and the bottom sediment core incubations to estimate nutrient fluxes in the seagrass, Zostera marina meadow. DIN (nitrate, nitrite and ammonium) concentrations were always low particularly during the Z. marina growing season (from spring to summer), and water exchanges caused by tidal currents hardly supplied nutrient demand for Z. marina. Sediment pore water also supplied insufficient nutrients to Z. marina, because pore water had less volume than the water column, although DIN concentrations of pore water were 10-100 fold higher than those of the water column. Nutrient flux from sediment to water column estimated by the sediment core incubation experiments showed a similar rate with tidal water exchange. Thus, our results suggested that Z. marina adapted for low nutrient concentrations and each nutrient source in the Z. marina meadow slightly contributed but could not support Z. marina growth. We found that another nutrient source, for example, precipitation, supplied high DIN to the Z. marina meadow. After rainfall, the DIN concentration of seawater in the Z. marina meadow increased 2-5 times higher. Moreover, nitrogen content of eelgrass also increased 2-3 times higher during several days. Those results suggested that Z. marina was usually exposed to a low nutrient concentration but could uptake abundant nutrients from temporary nutrient supplies such as precipitation.
6
Asahi, Toshimasa, Toshimasa Asahi, Kazuhiko Ichimi, Kazuhiko Ichimi, Kuninao Tada, and Kuninao Tada. "NUTRIENT DYNAMICS IN EELGRASS (ZOSTERA MARINA) MEADOW AND THE VARIATION OF NUTRIENT CONTENTS OF EELGRASS." In Managing risks to coastal regions and communities in a changing world. Academus Publishing, 2017. http://dx.doi.org/10.31519/conferencearticle_5b1b938251aa95.85691438.
Анотація:
Nutrient dynamics in seagrass beds and nutrient demands of seagrass biomass are not clear, although nutrient uptake of seagrass has been experimentally studied in the laboratory. We conducted the field observations and the bottom sediment core incubations to estimate nutrient fluxes in the seagrass, Zostera marina meadow. DIN (nitrate, nitrite and ammonium) concentrations were always low particularly during the Z. marina growing season (from spring to summer), and water exchanges caused by tidal currents hardly supplied nutrient demand for Z. marina. Sediment pore water also supplied insufficient nutrients to Z. marina, because pore water had less volume than the water column, although DIN concentrations of pore water were 10-100 fold higher than those of the water column. Nutrient flux from sediment to water column estimated by the sediment core incubation experiments showed a similar rate with tidal water exchange. Thus, our results suggested that Z. marina adapted for low nutrient concentrations and each nutrient source in the Z. marina meadow slightly contributed but could not support Z. marina growth. We found that another nutrient source, for example, precipitation, supplied high DIN to the Z. marina meadow. After rainfall, the DIN concentration of seawater in the Z. marina meadow increased 2-5 times higher. Moreover, nitrogen content of eelgrass also increased 2-3 times higher during several days. Those results suggested that Z. marina was usually exposed to a low nutrient concentration but could uptake abundant nutrients from temporary nutrient supplies such as precipitation.
7
Ecker, Lynne, Jacopo Saccheri, Biays Bowerman, James Ablett, Laurence Milian, Jay Adams, Hans Ludwig, and Michael Todosow. "An Infiltration Manufacturing Process for Nuclear Fuels." In Fourth International Topical Meeting on High Temperature Reactor Technology. ASMEDC, 2008. http://dx.doi.org/10.1115/htr2008-58204.
Анотація:
The Infiltrated Kernel Nuclear Fuel (IKNF) process deposits nuclear fuel into the naturally occurring porosity in graphite. IKNF consists of infiltrating uranyl nitrate dissolved in an organic solvent into the graphite and then heat-treating the sample at low (<300°C) temperatures to remove the solvent and convert the uranyl nitrate to UO2. Complete conversion to UC2 can then be accomplished by heating to temperatures higher than 3000°C. IKNF is extremely flexible: it is appropriate for very high temperature applications and heating the infiltrated product to intermediate temperatures (higher than 900°C) produces nuclear fuel with a range of chemistries in the U-C-O system (similar to the current US TRISO fuel). It is probable that the process can also be used to produce fuel containing transuranics. It is believed that IKNF will be less expensive, more robust and more suitable for on-line quality monitoring than current fuel fabrication method. Graphite infiltration involves a few, easily measurable and controllable variables. It is reproducible and predictable.
8
Kruizenga, Alan, David Gill, and Marianne LaFord. "Corrosion of Austenitic Alloys in Binary 60/40 Nitrate Salt at 600°C." In ASME 2013 7th International Conference on Energy Sustainability collocated with the ASME 2013 Heat Transfer Summer Conference and the ASME 2013 11th International Conference on Fuel Cell Science, Engineering and Technology. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/es2013-18057.
Анотація:
Industrial power utilities are using molten binary nitrate salt as a heat transfer fluid and thermal storage media for solar energy generation. Currently, the maximum bulk temperature is 565°C, due to concerns of salt degradation and materials compatibility with containment vessels. To increase overall cycle efficiency, one must increase the upper temperature of the nitrate salt, thereby lowering the levelized cost of electricity (LCoE) through higher power cycle efficiency. The corrosion performance of 316 stainless steel and Inconel 625 is currently characterized at 600°C. However, the 316SS has exhibited stress corrosion cracking (thought due to aqueous flush in Solar Two [1]), and while In625 performs well, its cost is prohibitive. Therefore, current research seeks to evaluate heat-resistant austenitic alloys for use with nitrate salts, ascertaining if they have superior performance characteristics, as well as assessing their mechanisms of corrosion. Sandia National Laboratory is researching four alloys (S35140, ATI332Mo, RA330, and HA556) for corrosion performance at 600°C for 3000 hours, under a cover gas of air. Air is used to simulate the chemistry conditions expected in a power plant. This work details the corrosion rate and the oxide structure for each alloy. Research indicates all alloys are very corrosion-resistant, with metal loss rates projected to be less than 21μm/year after 3000 hours. Though all alloys performed well, corrosion rate data for RA330 (Fe-19Cr-35Ni + minor elements) currently appears to exhibit a linear loss mechanism. In conclusion, this paper will explore the differences in oxide formation between these similar alloys.
9
Armijo, Kenneth M., Matthew D. Carlson, Dwight S. Dorsey, Joshua M. Christian, and Craig S. Turchi. "System Design of a 2.0 MWth Sodium/Molten Salt Pilot System." In ASME 2020 14th International Conference on Energy Sustainability. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/es2020-1622.
Анотація:
Abstract Nitrate molten salt concentrating solar power (CSP) systems are currently deployed globally and are considered state-of the art heat transfer fluids (HTFs) for present day high-temperature operation. Although slightly higher limits may be possible with molten salt, to fully realize SunShot efficiency goals of $15/kWhth HTFs and an LCOE of 6¢/kWh, HTF technologies working at higher temperatures (e.g., 650 °C to 750 °C) will require an alternative to molten salts, such as with alkali metal systems. This investigation explores the development of a 2.0 MWth sodium receiver system that employs a sodium receiver as the HTF, as well as with a ternary chloride (20%NaCl/40%MgCl/40%KCl by mol wt.%) salt as a thermal energy storage (TES) medium to facilitate a 6-hr. storage duration. A sodium-to-salt heat exchanger model as well as a salt-to-sCO2 primary heat exchanger model are employed and evaluated in this investigation. A thermodynamic system design model was developed using Engineering Equation Solver (EES) where state properties were calculated at inlets and outlets along both hot and cold legs of the pilot-scale plant. This investigation assesses receiver performance as well as system efficiency studies for the pump and system operational ranges. Results found that high efficiency sodium receivers were found to have higher heat transfer coefficients and required far less spreading of incident flux. The system performance model results suggest that for a pump speed of 2400 RPM, respective hot and cold pump TDH values were determined to be 260.1–307 ft. and 260.1–307 ft for pump flow rates of 90–120 GPM.
10
Bradshaw, Robert W., and Nathan P. Siegel. "Molten Nitrate Salt Development for Thermal Energy Storage in Parabolic Trough Solar Power Systems." In ASME 2008 2nd International Conference on Energy Sustainability collocated with the Heat Transfer, Fluids Engineering, and 3rd Energy Nanotechnology Conferences. ASMEDC, 2008. http://dx.doi.org/10.1115/es2008-54174.
Анотація:
Thermal energy storage can enhance the utility of parabolic trough solar power plants by providing the ability to match electrical output to peak demand periods. An important component of thermal energy storage system optimization is selecting the working fluid used as the storage media and/or heat transfer fluid. Large quantities of the working fluid are required for power plants at the scale of 100-MW, so maximizing heat transfer fluid performance while minimizing material cost is important. This paper reports recent developments of multi-component molten salt formulations consisting of common alkali nitrate and alkaline earth nitrate salts that have advantageous properties for applications as heat transfer fluids in parabolic trough systems. A primary disadvantage of molten salt heat transfer fluids is relatively high freeze-onset temperature compared to organic heat transfer oil. Experimental results are reported for formulations of inorganic molten salt mixtures that display freeze-onset temperatures below 100°C. In addition to phase-change behavior, several properties of these molten salts that significantly affect their suitability as thermal energy storage fluids were evaluated, including chemical stability and viscosity. These alternative molten salts have demonstrated chemical stability in the presence of air up to approximately 500°C in laboratory testing and display chemical equilibrium behavior similar to Solar Salt. The capability to operate at temperatures up to 500°C may allow an increase in maximum temperature operating capability vs. organic fluids in existing trough systems and will enable increased power cycle efficiency. Experimental measurements of viscosity were performed from near the freeze-onset temperature to about 200°C. Viscosities can exceed 100 cP at the lowest temperature but are less than 10 cP in the primary temperature range at which the mixtures would be used in a thermal energy storage system. Quantitative cost figures of constituent salts and blends are not currently available, although, these molten salt mixtures are expected to be inexpensive compared to synthetic organic heat transfer fluids. Experiments are in progress to confirm that the corrosion behavior of readily available alloys is satisfactory for long-term use.
Звіти організацій з теми "Legs nitraté":
1
Bendikov, Michael, and Thomas C. Harmon. Development of Agricultural Sensors Based on Conductive Polymers. United States Department of Agriculture, August 2006. http://dx.doi.org/10.32747/2006.7591738.bard.
Анотація:
In this 1-year feasibility study, we tried polymerization of several different monomers, commercial as well as novel, specially designed and synthesized for this project in the presence of the nitrate ion to produce imprinted conductive polymers. Polymers 1 and 2 (shown below) produced a response to nitrate, but one inferior to that produced by a polypyrrole (Ppy)-based sensor (which we demonstrated prior to this study). Thus, we elected to proceed with improving the stability of the Ppy-based sensor. In order to improve stability of the Ppy-based sensor, we created a two-layer design which includes nitrate-doped Ppy as an inner layer, and nitrate-doped PEDOT as the outer layer. PEDOT is known for its high environmental stability and conductivity. This design has demonstrated promise, but is still undergoing optimization and stability testing. Previously we had failed to create nitrate-doped PEDOT in the absence of a Ppy layer. Nitrate-doped PEDOT should be very promising for sensor applications due to its high stability and exceptional sensing properties as we showed previously for sensing of perchlorate ions (by perchlorate-doped PEDOT). During this year, we have succeeded in preparing nitrate-doped PEDOT (4 below) by designing a new starting monomer (compound 3 below) for polymerization. We are currently testing this design for nitrate sensing. In parallel with the fabrication design studies, we fabricated and tested nitrate-doped Ppy sensors in a series of flow studies under laboratory and field conditions. Nitrate-doped Ppy sensors are less stable than is desirable but provide excellent nitrate sensing characteristics for the short-term experiments focusing on packaging and deployment strategies. The fabricated sensors were successfully interfaced with a commercial battery-powered self-logging (Onset Computer Hobo Datalogger) and a wireless data acquisition and transmission system (Crossbow Technologies MDA300 sensor interface and Mica2 wireless mote). In a series of flow-through experiments with water, the nitrate-doped Ppy sensors were exposed to pulses of dissolved nitrate and compared favorably with an expensive commercial sensor. In 24-hour field tests in both Merced and in Palmdale, CA agricultural soils, the sensors responded to introduced nitrate pulses, but with different dynamics relative to the larger commercial sensors. These experiments are on-going but suggest a form factor (size, shape) effect of the sensor when deployed in a porous medium such as soil. To fill the need for a miniature reference electrode, we identified and tested one commercial version (Cypress Systems, ESA Mini-reference electrode) which works well but is expensive ($190). To create an inexpensive miniature reference electrode, we are exploring the use of AgCl-coated silver wire. This electrode is not a “true” reference electrode; however, it can calibrated once versus a commercial reference electrode at the time of deployment in soil. Thus, only one commercial reference electrode would suffice to support a multiple sensor deployment.