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1
Rosevear, J., and JFK Wilshire. "A comparison of the reactions of some ethyl N-Arylcarbamates with those of the corresponding acetanilides. I. Nitration." Australian Journal of Chemistry 38, no. 5 (1985): 723. http://dx.doi.org/10.1071/ch9850723.
Повний текст джерелаАнотація:
The reactions of some ethyl N- arylcarbamates and of the corresponding acetanilides towards 1 equiv. of sodium nitrate in concentrated sulfuric acid at 0-5° have been compared with one another and have been found to exhibit significant differences. Except in the case of the unsubstituted analogues, nitration of the carbamates was found to occur significantly more quickly than that of the acetanilides as shown by ( i ) a representative competitive nitration, and (ii) the fact the carbamates containing a nitro group are nitrated smoothly whereas the corresponding nitroacetanilides are slow to react. On the basis of competitive reactions, it is suggested that this difference in reactivity is due to steric factors.
2
Elmes, Victoria K., Andrew P. Hurt, and Nichola J. Coleman. "Mixed-Phase Ion-Exchangers from Waste Amber Container Glass." Materials 14, no. 17 (August 27, 2021): 4887. http://dx.doi.org/10.3390/ma14174887.
Повний текст джерелаАнотація:
This study investigated the one-pot hydrothermal synthesis of mixed-phase ion-exchangers from waste amber container glass and three different aluminium sources (Si/Al = 2) in 4.5 M NaOH(aq) at 100 °C. Reaction products were characterised by X-ray diffraction analysis, Fourier transform infrared spectroscopy, 27Al and 29Si magic angle spinning nuclear magnetic resonance spectroscopy and scanning electron microscopy at 24, 48 and 150 h. Nitrated forms of cancrinite and sodalite were the predominant products obtained with reagent grade aluminium nitrate (Al(NO3)3∙9H2O). Waste aluminium foil gave rise to sodalite, tobermorite and zeolite Na-P1 as major phases; and the principal products arising from amorphous aluminium hydroxide waste were sodalite, tobermorite and zeolite A. Minor proportions of the hydrogarnet, katoite, and calcite were also present in each sample. In each case, crystallisation was incomplete and products of 52, 65 and 49% crystallinity were obtained at 150 h for the samples prepared with aluminium nitrate (AN-150), aluminium foil (AF-150) and amorphous aluminium hydroxide waste (AH-150), respectively. Batch Pb2+-uptake (~100 mg g−1) was similar for all 150-h samples irrespective of the nature of the aluminium reagent and composition of the product. Batch Cd2+-uptakes of AF-150 (54 mg g−1) and AH-150 (48 mg g−1) were greater than that of AN-150 (36 mg g−1) indicating that the sodalite- and tobermorite-rich products exhibited a superior affinity for Cd2+ ions. The observed Pb2+- and Cd2+-uptake capacities of the mixed-product ion-exchangers compared favourably with those of other inorganic waste-derived sorbents reported in the literature.
3
Rosenkranz, Herbert S., and Gilles Klopman. "CASE, the computer-automated structure evaluation method, correctly predicts the low mutagenicity for Salmonella of nitrated cyclopenta-fused polycyclic aromatic hydrocarbons." Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis 199, no. 1 (May 1988): 95–101. http://dx.doi.org/10.1016/0027-5107(88)90234-5.
Повний текст джерела
4
Rosenkranz, Herbert S., and Gilles Klopman. "CASE, the computer-automated structure evaluation method, correctly predicts the low mutagenicity for Salmonella of nitrated cyclopenta-fused polycyclic aromatic hydrocarbons." Mutation Research/Environmental Mutagenesis and Related Subjects 199, no. 1 (May 1988): 95–101. http://dx.doi.org/10.1016/0165-1161(88)90236-1.
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5
Yamato, Takehiko, Hideo Kamimura, and Hirohisa Tsuzuki. "ipso-Nitration of tert-butyl[n.2]metacyclophanes; through-space electronic interactions between two benzene rings." Canadian Journal of Chemistry 76, no. 7 (July 1, 1998): 997–1005. http://dx.doi.org/10.1139/v98-111.
Повний текст джерелаАнотація:
The selective introduction of one or two nitro groups by direct replacement of tert-butyl groups via the ipso aromatic nitration of the meta-bridged aromatic compounds having two arene rings is described. The ipso-nitration at the tert-butyl groups of syn- and anti-di-tert-butyl-dimethoxy[n.2]metacyclophanes 1 is attributed to the highly activated character of the aryl ring and the increased stabilization of a σ-complex intermediate arising from the dienone-type σ-complex intermediate possible in the case of an internally methoxy substituent. However, only one tert-butyl group is ipso-nitrated in the mild reaction conditions such as copper(II) nitrate in an acetic anhydride solution because of deactivation of the second aromatic ring by the introduced nitro group. A first σ-complex intermediate would be stabilized by two types of the through-space electronic interaction, i.e., face-to-face overlapping and intra-annular interaction with the opposing benzene ring, thus accelerating the reaction. The higher yields of mononitrated product are obtained in syn-conformer than in anti-conformer. Therefore, face-to-face overlapping might be much more favourable to stabilize the first σ-complex intermediate than the intra-annular interaction. On the other hand, nitration of 1 with fuming nitric acid afforded the two-fold ipso-nitration product 3 in quantitative yield. Thus, the number of ipso-nitration at the tert-butyl groups of 1 was strongly affected by the reactivity of the nitration reagent.Key words: cyclophanes, electrophilic aromatic substitutions, ipso-nitration, σ-complex intermediates, through-space electronic interactions.
6
Kuhn, Merrily. "Nitrates." AACN Advanced Critical Care 3, no. 2 (May 1, 1992): 409–22. http://dx.doi.org/10.4037/15597768-1992-2013.
Повний текст джерелаАнотація:
Nitrates have been used for the last 130 years to treat and control the symptoms of angina pectoris. Within the last 15 years, nitrates also have been shown to limit infarct size and to be beneficial in the treatment of patients with severe intractable heart failure, cardiogenic shock, severe mitral and aortic regurgitation, hypertensive episodes, and portal hypertension. The adequate use of nitrates to treat these disorders requires the ability to document a hemodynamic response and to closely monitor the adverse consequences of this therapy. Nitrates work by directly relaxing smooth muscle in resistance and capacitance vessels, thereby causing generalized dilation. Nitrates reduce preload and, at higher doses, reduce systemic vascular resistance and afterload. This chapter reviews the physiologic mechanisms that underlie nitrate therapy, the appropriate indications for nitrate use, the usefulness of specific agents, and their appropriate nursing implications
7
TASKER, A. D., L. ROBSON, S. M. HANKIN, K. W. D. LEDINGHAM, R. P. SINGHAL, X. FANG, T. MCCANNY, et al. "Ultrafast laser analysis of nitro-PAHs using laser desorption/femtosecond ionization mass spectrometry." Laser and Particle Beams 19, no. 2 (April 2001): 205–8. http://dx.doi.org/10.1017/s0263034601192062.
Повний текст джерелаАнотація:
Analytical interest in nitrated polycyclic aromatic hydrocarbons (nitro-PAHs) is related to their high mutagenicity and potential presence in a variety of environmental media such as diesel exhaust and urban air particulate matter. Furthermore, fundamental interest in these molecular systems stems from the photophysics of the labile NO2 functional group, which has been investigated using mass spectrometry. The nitro-PAHs, 1-nitronaphthalene, 9-nitroanthracene, and 1-nitropyrene, have been studied using both femtosecond (λ = 395 and 790 nm) and nanosecond (λ = 266 nm) lasers coupled to a reflectron time of flight mass spectrometer. Analysis of mass spectra taken over a range of intensities (1014–1015 W/cm2) has demonstrated that structurally specific ions can be observed for each molecule, with little or no fragmentation at lower intensities. It has also been found that an intact parent ion can be detected using femtosecond ionization at 395 nm in each case. This work demonstrates the potential use of laser desorption/femtosecond laser mass spectrometry (LD/FLMS) as an analytical technique for the detection of nitro-PAHs and other environmental pollutants and as a means of studying the photodynamics of labile molecular systems.
8
Lanas, A., E. Bajador, P. Serrano, M. Arroyo, J. Fuentes, and S. Santolaria. "Effects of Nitrate and Prophylactic Aspirin on Upper Gastrointestinal Bleeding: A Retrospective Case–Control Study." Journal of International Medical Research 26, no. 3 (June 1998): 120–28. http://dx.doi.org/10.1177/030006059802600302.
Повний текст джерелаАнотація:
Experimental studies suggest that nitric-oxide-releasing drugs reduce gastroduodenal damage induced by non-steroidal anti-inflammatory drugs, but it is not known whether these agents have this effect in humans. The aim of the present study was to evaluate the risk of upper gastrointestinal bleeding in patients who receive aspirin and nitrates for vascular occlusive diseases. This was a retrospective case–control study of 736 consecutive patients admitted with upper gastrointestinal bleeding, compared with 1472 age- and sex-matched hospital controls. Chronic low-dose aspirin regimens had been used by 12.6% of cases and 5.7% of controls, nitrates by 4.8% and 5.8%, and combined nitrates and low-dose aspirin by 2.7% and 1.9%, respectively. Logistic regression analysis identified low-dose aspirin use as an independent risk factor for gastrointestinal bleeding, whereas nitrate use was found to be a protective factor. The combination of both nitrate and low-dose aspirin was not associated with an increased risk of bleeding.
9
Macuh, Matjaž, and Bojan Knap. "Effects of Nitrate Supplementation on Exercise Performance in Humans: A Narrative Review." Nutrients 13, no. 9 (September 13, 2021): 3183. http://dx.doi.org/10.3390/nu13093183.
Повний текст джерелаАнотація:
Nitrates have become increasingly popular for their potential role as an ergogenic aid. The purpose of this article was to review the current scientific evidence of nitrate supplementation on human performance. The current recommendation of nitrate supplementation is discussed, as well as possible health complications associated with nitrate intake for athletes, and dietary strategies of covering nitrate needs through sufficient intake of nitrate-rich foods alone are presented. Pubmed, Scopus, and Web of Science were searched for articles on the effects of nitrate supplementation in humans. Nitrates are an effective ergogenic aid when taken acutely or chronically in the range of ~5–16.8 mmol (~300–1041 mg) 2–3 h before exercise and primarily in the case of exercise duration of ~10–17 min in less trained individuals (VO2max < 65 mL/kg/min). Nitrate needs are most likely meet by ingesting approximately 250–500 g of leafy and root vegetables per day; however, dietary supplements might represent a more convenient and accurate way of covering an athlete’s nitrate needs. Athletes should refrain from mouthwash usage when nitrate supplementation benefits are desired. Future research should focus on the potential beneficial effects of nitrate supplementation on brain function, possible negative impacts of chronic nitrate supplementation through different nitrate sources, and the effectiveness of nitrate supplementation on strength and high-intensity intermittent exercise.
10
Buenger, Jon W., and Vincent F. Mauro. "Organic Nitrate-Induced Methemoglobinemia." DICP 23, no. 4 (April 1989): 283–88. http://dx.doi.org/10.1177/106002808902300402.
Повний текст джерелаАнотація:
Metabolism of organic nitrates results in the formation of inorganic nitrites that can oxidize hemoglobin to methemoglobin. Clinical trials have investigated the risk of developing methemoglobinemia during the therapeutic use of organic nitrates. Based on the results of these trials, organic nitrate use does appear to increase methemoglobin content but not to a clinically significant extent. These elevations may be related to dose but study design prevents determination of any dose-response relationship. Despite these results, several case reports of patients experiencing clinically significant methemoglobinemia can be found in the literature. These patients generally received organic nitrates at doses greater than those used in the clinical trials, and several were diagnosed early during coronary surgery. Renal dysfunction and concurrent use of methemoglobin inducers may be contributing factors. Patients receiving organic nitrates should be monitored for symptoms suggestive of methemoglobinemia, especially while receiving large doses. Treatment of nitrate-induced methemoglobinemia consists of discontinuing the medication and, when necessary, administering methylene blue.
11
Clarke, Jennifer L., Irida Kastrati, Linda J. Johnston, and Gregory RJ Thatcher. "Photochemical reactions of thiols with organic nitrates Oxygen atom transfer via a thionitrate." Canadian Journal of Chemistry 84, no. 4 (April 1, 2006): 709–19. http://dx.doi.org/10.1139/v06-056.
Повний текст джерелаАнотація:
Nitroglycerin is an organic nitrate that has been used in the clinical treatment of angina for 130 years, yet important details of its mechanism of action remain unanswered. The biological activity of nitrates suggests that they are bioactivated to NO via a three-electron reduction. The involvement of free or bound protein thiols in this reduction has often been proposed. To examine the involvement of thiyl radicals in such a process, the photochemical generation of benzenethiyl radical from thiol and disulfide precursors was studied in the presence of isopropyl nitrate. Analysis of reaction products and kinetics led to the conclusion that photolysis of the nitrate to NO2 dominated the observed photochemistry. Formation of sulfonothioate and NO as products, and trapping of NO2 by 4-chlorophenol, indicated a mechanism involving oxygen atom transfer from N to S via a thionitrate intermediate. The results of the study did not indicate a rapid reaction between thiyl radical and organic nitrate. Despite weak nitrate absorption of light >300 nm and a relatively high BDE for homolysis to give NO2, the photochemistry under thiyl-generating conditions was driven by nitrate photolysis to NO2. A novel nitrate, containing a phenyl disulfanyl group linked to nitrate groups, did not undergo photolysis to NO2 or generate sulfonothioate, but did yield NO. These observations suggest that reaction between thiyl radicals and nitrates leading to NO release is a viable pathway, but it is subservient to other competing reactions, such as photolysis, in the case of IPN, and reaction with thiolate, in the case of the novel nitrate.Key words: nitrate, photolysis, thiyl radical, nitrogen dioxide, nitric oxide.
12
Sabolová, Monika, and Lenka Kouřimská. "Vitamin C and nitrates contents in fruit and vegetables from farmers' markets and supermarkets." Potravinarstvo Slovak Journal of Food Sciences 14 (November 28, 2020): 1124–30. http://dx.doi.org/10.5219/1347.
Повний текст джерелаАнотація:
Fruits and vegetables are the best food sources of vitamin C. However, fruits and vegetables can be also sources of potentially harmful substances to the human body, nitrates being one of these. The aim of this study was to compare vitamin C and nitrates contents in selected fruits and vegetables from supermarkets and local farmers' markets. Samples of plums, strawberries, apples, spinach, red peppers and tomatoes were chosen for analysis. Content of vitamin C and nitrates was analyzed by HPLC/DAD. The hypothesis was that local market fruits and vegetables contain more vitamin C and fewer nitrates than samples bought in supermarkets. Laboratory analyses showed that there were differences in vitamin C in the case of strawberries, tomatoes and red peppers. The highest level of ascorbic acid was in red pepper samples (141 mg.100g-1). In the case of fruit, the highest content was in strawberries (70 mg.100g-1). As far as nitrates content is concerned, in three cases out of six, the fruit and vegetables we tested from farmers' markets contained lower concentrations of nitrates than those purchased at supermarkets and the hypothesis was accepted in these cases. There was no significant difference between the nitrate content of the local market and supermarket strawberries and red peppers. Tomatoes had significantly higher nitrate content when purchased at farmers' markets than at supermarkets. Leafy vegetables are considered to be the major source of nitrates, and this was confirmed by this study. The highest content of nitrates was in the spinach sample (2969 mg.kg-1). Among all fruit samples, strawberries had the highest nitrates levels (maximum 131 mg.kg-1). The results of this work showed that the content of ascorbic acid and nitrates differs significantly depending on the type of fruit or vegetables.
13
Dzuban, A. V., A. A. Galstyan, N. A. Kovalenko, and I. A. Uspenskaya. "Thermodynamic Modeling of Multicomponent Rare Earth Nitrates Aqueous Systems." Russian Journal of Physical Chemistry A 95, no. 12 (December 2021): 2394–404. http://dx.doi.org/10.1134/s0036024421120074.
Повний текст джерелаАнотація:
Abstract Solubility constants of rare earth (RE) nitrates crystalline hydrates are determined in a wide temperature range (−30 to 120°C), salts solubilities and phase diagrams of water–RE nitrate systems are calculated. For multicomponent (n > 5) solutions of RE nitrates the assessment of solution properties as well as phase diagrams are shown to be feasible within experimental uncertainty. In case of mixtures of RE nitrates with similar hydrodynamic radii of ions, the parameters of RE1–RE2 interparticle interaction can be ignored without losing accuracy of thermodynamic modeling.
14
Dahab, M. F., Y. W. Lee, and Istvan Bogardi. "A rule-based fuzzy-set approach to risk analysis of nitrate-contaminated groundwater." Water Science and Technology 30, no. 7 (October 1, 1994): 45–52. http://dx.doi.org/10.2166/wst.1994.0302.
Повний текст джерелаАнотація:
Groundwater nitrate contamination has been a subject of concern because nitrate salts can induce infant methemoglobinemia and possibly human gastric cancer. In general, nitrates in drinking water may not be the main component of total nitrate intake, but nitrate-contaminated drinking water can make an important contribution to total nitrate intake. In this paper, a nitrate risk-assessment methodology is developed to assist decision makers in estimating human health risks corresponding to a particular nitrate dose to humans and in determining whether regulatory action must be taken to reduce the health risks. The case of a community with a nitrate water quality problem is used to illustrate the nitrate risk assessment methodology. The uncertainty associated with assessing health risks of nitrate and its impact on results are represented by using a fuzzy-set approach and incorporated into the nitrate risk assessment methodology. Therefore, a nitrate risk assessment can be made that is more realistic and appropriate than the one made without taking uncertainty into account.
15
Ramesh, K., S. Shylaja, S. Ramgopal, A. Sambashiva Rao та K. C. Rajanna. "Poly(ethylene glycol) Supported Metal Nitrates as Well-Organized Reagents for Hunsdiecker Conversion of α,β-Unsaturated Acids to β-Nitrostyrenes under Solvent and Acid-Free Conditions". Asian Journal of Chemistry 31, № 8 (28 червня 2019): 1798–800. http://dx.doi.org/10.14233/ajchem.2019.21975.
Повний текст джерелаАнотація:
Poly(ethylene glycol) (PEG) supported metal nitrates such as ferric nitrate and manganese nitrate were accomplished as well-organized reagents for Hunsdiecker conversion of α,β-unsaturated acids to β-nitrostyrenes under acid-free and solvent free conditions using grind-stone technique. However, in the case of unsaturated aliphatic acids, nitro alkene derivatives were obtained as products. PEG-400 was found the best among the other PEGs (PEG-200,300, 400, 600, 3000 and 6000) used in this protocol.
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Defterdarović, Jasmina, Lana Filipović, Filip Kranjčec, Gabrijel Ondrašek, Diana Kikić, Alen Novosel, Ivan Mustać, et al. "Determination of Soil Hydraulic Parameters and Evaluation of Water Dynamics and Nitrate Leaching in the Unsaturated Layered Zone: A Modeling Case Study in Central Croatia." Sustainability 13, no. 12 (June 12, 2021): 6688. http://dx.doi.org/10.3390/su13126688.
Повний текст джерелаАнотація:
Nitrate leaching through soil layers to groundwater may cause significant degradation of natural resources. The aims of this study were: (i) to estimate soil hydraulic properties (SHPs) of the similar soil type with same management on various locations; (ii) to determine annual water dynamics; and (iii) to estimate the impact of subsoil horizon properties on nitrate leaching. The final goal was to compare the influence of different SHPs and layering on water dynamics and nitrate leaching. The study was conducted in central Croatia (Zagreb), at four locations on Calcaric Phaeozem, Calcaric Regosol, and Calcaric Fluvic Phaeozem soil types. Soil hydraulic parameters were estimated using the HYPROP system and HYPROP-FIT software. Water dynamics and nitrate leaching were evaluated using HYDRUS 2D/3D during a period of 365 days. The amount of water in the soil under saturated conditions varied from 0.422 to 0.535 cm3 cm–3 while the hydraulic conductivity varied from 3 cm day−1 to 990.9 cm day−1. Even though all locations have the same land use and climatic conditions with similar physical properties, hydraulic parameters varied substantially. The amount and velocity of transported nitrate (HYDRUS 2D/3D) were affected by reduced hydraulic conductivity of the subsoil as nitrates are primarily transported via advective flux. Despite the large differences in SHPs of the topsoil layers, the deeper soil layers, having similar SHPs, imposed a buffering effect preventing faster nitrate downward transport. This contributed to a very similar distribution of nitrates through the soil profile at the end of simulation period. This case study indicated the importance of carefully selecting relevant parameters in multilayered soil systems when evaluating groundwater pollution risk.
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Sieczka, Anna, Filip Bujakowski, and Eugeniusz Koda. "Modelling groundwater flow and nitrate transport: a case study of an area used for precision agriculture in the middle part of the Vistula River valley, Poland." Geologos 24, no. 3 (December 1, 2018): 225–35. http://dx.doi.org/10.2478/logos-2018-0023.
Повний текст джерелаАнотація:
Abstract The present paper discusses studies related to the preparation of a hydrogeological model of groundwater flow and nitrate transport in an area where a precision farming system is applied. Components of water balance were determined using the UnSat Suite Plus software (HELP model), while the average infiltration rate calculated for the study area equalled 20 per cent. The Visual MODFLOW software was used for the purpose of modelling in the saturated zone. Hydrogeological parameters of the model layers, inclusive of hydraulic conductivity, were defined on the basis of results of column tests that were carried out under laboratory conditions (column experiment). Related to the dose of mineral nitrogen used in precision fertilisation (80 kg N/ha), scenarios of the spread of nitrates in the soil-water environment were worked out. The absolute residual mean error calculated for nitrate concentrations obtained from laboratory and modelling studies equalled 0.188 mg/L, the standard error of the estimate equalling 0.116 mg/L. Results obtained were shown graphically in the form of hydroisohypse maps and nitrate isolines. Conclusions were drawn regarding the possibility of using numerical modelling techniques in predicting transport and fate of nitrates from fertilisers applied in precision agriculture systems.
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Nájera, Cinthia, and Miguel Urrestarazu. "Effect of the Intensity and Spectral Quality of LED Light on Yield and Nitrate Accumulation in Vegetables." HortScience 54, no. 10 (October 2019): 1745–50. http://dx.doi.org/10.21273/hortsci14263-19.
Повний текст джерелаАнотація:
At present, trends exist in the production of food for the benefit of human health. The negative effect of an excessive intake of nitrates accumulated in vegetables is well known, causing worldwide concern. Light plays an important role in the accumulation of this ion. The objective of this work was to evaluate the effect of light-emitting diode (LED) spectra used in artificial lighting for horticulture on the accumulation of nitrates in leafy and root vegetables compared with the effects with white LED lights. Two independent experiments were carried out in the culture chamber. In Expt. 1, six species of nitrate accumulators were used: arugula, spinach, lettuce, endive, radish, and beetroot. In Expt. 2, four lettuce cultivars were used. In both experiments, the treatments were two spectra—T1 = AP67 Valoya® and the control (T0) = white Roblan®—at two illumination intensities [high (H) and low (L)] with a 16/8-hour (day/night) photoperiod. The fresh biomass and the concentration of nitrates were measured at 35 days of treatment posttransplantation. An important and significant increase of 50% of the mean fresh weight was obtained in all the species when the light intensity increased. Except for spinach in the low-intensity treatment, all nitrate content values were less than the maximum limits of European regulation. The nitrate content generally decreased with increasing intensity, and this benefit was greater in the T1 treatment. T0 showed a reduction in the nitrate content compared with T1 in only one case, which was the H in beetroot. A large and significant reduction was observed in the nitrate content in T1. For L in Expt. 1, the nitrate decrease was 18%, whereas for H, it was 35%. In Expt. 2, the decrease in the nitrate content was 10% for L and 21% for H. A greater benefit was derived when using the photosynthetic spectrum in the growing chambers under low light intensity.
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Jendia, Ahmed H., Sofiah Hamzah, A. A. Abuhabib, and Nizam M. El-Ashgar. "Removal of nitrate from groundwater by eggshell biowaste." Water Supply 20, no. 7 (July 13, 2020): 2514–29. http://dx.doi.org/10.2166/ws.2020.151.
Повний текст джерелаАнотація:
Abstract This study concerns nitrate ion removal, which is one of the most dangerous issues of water contamination in the Gaza Strip. Eggshell biowaste was used as a denitrification biosorbent for water and groundwater. The results showed that the highest removal of nitrate was at pH 6.0–7.5, eggshell particle size in the range 90–710 μm, drying temperature at 45 °C, incubation temperature of adsorbent/adsorbate mixture at 37 °C and contact time of 24 hours. At the optimum conditions, the maximum amount of nitrate removed was 8.25 mg/g eggshell, when 1,500 mg/L of NO3− was applied. It was found that the eggshell biosorbent could be recovered and reused for removing the nitrate with removal capacity of 0.79–0.92 mg/g eggshell (79–92%) in the case of washed samples while the removal capacity was 0.79–0.92 mg/g eggshell (89–93%) in the case of unwashed samples when 100 mg/L of NO3− was applied. Results using the eggshell column method showed a nitrate removal efficiency of 90% at a flow rate ≤2 mL/min of the eluents. The biosorbent was applied to remove nitrates in real groundwater samples from different locations in the Gaza Strip and the efficiency of nitrate removal was in the range (77.4–93%).
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Taneja, Pinky, Pawan Labhasetwar, Pranav Nagarnaik, and Jeroen H. J. Ensink. "The risk of cancer as a result of elevated levels of nitrate in drinking water and vegetables in Central India." Journal of Water and Health 15, no. 4 (May 11, 2017): 602–14. http://dx.doi.org/10.2166/wh.2017.283.
Повний текст джерелаАнотація:
The objective of the present study was to determine the effect of nitrates on the incidence of gastrointestinal (GI) cancer development. Nitrate converted to nitrite under reducing conditions of gut results in the formation of N-nitrosamines which are linked to an increased gastric cancer risk. A population of 234 individuals with 78 cases of GI cancer and 156 controls residing at urban and rural settings in Nagpur and Bhandara districts of India were studied for 2 years using a case-control study. A detailed survey of 16 predictor variables using Formhub software was carried out. Nitrate concentrations in vegetables and primary drinking water supplies were measured. The logistic regression model showed that nitrate was statistically significant in predicting increasing risk of cancer when potential confounders were kept at base level (P value of 0.001 nitrate in drinking water; 0.003 for nitrate in vegetable) at P < 0.01. Exposure to nitrate in drinking water at >45 mg/L level of nitrate was associated with a higher risk of GI cancers. Analysis suggests that nitrate concentration in drinking water was found statistically significant in predicting cancer risk with an odds ratio of 1.20.
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Duncianu, Marius, Marc David, Sakthivel Kartigueyane, Manuela Cirtog, Jean-François Doussin, and Benedicte Picquet-Varrault. "Measurement of alkyl and multifunctional organic nitrates by proton-transfer-reaction mass spectrometry." Atmospheric Measurement Techniques 10, no. 4 (April 18, 2017): 1445–63. http://dx.doi.org/10.5194/amt-10-1445-2017.
Повний текст джерелаАнотація:
Abstract. A commercial PTR-TOF-MS has been optimized in order to allow the measurement of individual organic nitrates in the atmosphere. This has been accomplished by shifting the distribution between different ionizing analytes, H3O+∕ H3O+(H2O)n or NO+∕ NO2+. The proposed approach has been proven to be appropriate for the online detection of individual alkyl nitrates and functionalized nitrates. It has been shown that hydroxyl and ketonitrates have a high affinity towards NO+, leading to the formation of an adduct that allows the easy identification of the organic nitrate (R) from the R–NO+ ion signal. The recorded sensitivities for both ionization modes correspond to detection limits of tens of ppt min−1 in the case of hydroxy- and ketonitrates. Alkyl nitrates exhibit a moderate affinity towards NO+ ionization leading to detection units of few hundreds of ppt and the highest sensitivity in H3O+ mode was obtained for the water adducts signals. However, this method exhibits much lower capabilities for the detection of peroxyacetyl nitrates with detection limits in the ppb range.
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Zarzecka-Napierala, Magdalena, and Krzystof Haberko. "Synthesis and characterization of yttrium aluminium garnet (YAG) powders." Processing and Application of Ceramics 1, no. 1-2 (2007): 69–74. http://dx.doi.org/10.2298/pac0702069z.
Повний текст джерелаАнотація:
In this paper synthesis and characterization of YAG powders, prepared by a process based on complexing properties of citric acid, was reported. Influence of citric acid estrification induced by 2-propanol or ethylene glycol on the system homogeneity was investigated. These reagents were introduced to aqueous solution of yttrium and aluminium nitrates. A variety of powders from Al2O3-Y2O3 system with different phase composition were obtained by altering the citrate to nitrate ratio. Evolution of the powders phase composition vs. temperature was investigated using DTA/TG, XRD, and FT-IR methods. The most interesting results were observed in case of the citric acid - propanol - relative nitrates system. The mole ratio of these reagents equal to 1: 2.5: 2.5 (nitrates (Al,Y): citric acid: 2-propanol) allowed to synthesize pure YAG phase powders at temperature as low as 950?C.
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Nazir, Sarfraz Ahmed, Sheraz Nazir, Sanjay Kumar, and Charles Ilsley. "Multifocal Severe Coronary Artery Vasospasm Mistaken for Diffuse Atherosclerosis: A Case Report." Case Reports in Medicine 2010 (2010): 1–4. http://dx.doi.org/10.1155/2010/202156.
Повний текст джерелаАнотація:
Spontaneous severe multivessel coronary artery vasospasm is a rare but important cause of morbidity. One-third of patients have normal coronary vasculature, and these pose a significant therapeutic dilemma as lack of clinical suspicion might potentially lead to unnecessary revascularization therapies. A patient with resting chest pain and ischaemic electrocardiography demonstrated severe coronary obstruction at catheter angiography. Preangioplasty further information highlighted spasm as the likely cause and the angiographic abnormalities resolved post intracoronary nitrate. This paper emphasises thorough history-taking and judicious use of nitrates during diagnostic coronary angiography in such patients. This may negate the need for more complex cardiac interventions.
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Tapia, A., F. Villanueva, M. S. Salgado, B. Cabañas, E. Martínez, and P. Martín. "Atmospheric degradation of 3-methylfuran: kinetic and products study." Atmospheric Chemistry and Physics 11, no. 7 (April 5, 2011): 3227–41. http://dx.doi.org/10.5194/acp-11-3227-2011.
Повний текст джерелаАнотація:
Abstract. A study of the kinetics and products obtained from the reactions of 3-methylfuran with the main atmospheric oxidants has been performed. The rate coefficients for the gas-phase reaction of 3-methylfuran with OH and NO3 radicals have been determined at room temperature and atmospheric pressure (air and N2 as bath gases), using a relative method with different experimental techniques. The rate coefficients obtained for these reactions were (in units cm3 molecule−1 s−1) kOH = (1.13 ± 0.22) × 10−10 and kNO3 = (1.26 ± 0.18) × 10−11. Products from the reaction of 3-methylfuran with OH, NO3 and Cl atoms in the absence and in the presence of NO have also been determined. The main reaction products obtained were chlorinated methylfuranones and hydroxy-methylfuranones in the reaction of 3-methylfuran with Cl atoms, 2-methylbutenedial, 3-methyl-2,5-furanodione and hydroxy-methylfuranones in the reaction of 3-methylfuran with OH and NO3 radicals and also nitrated compounds in the reaction with NO3 radicals. The results indicate that, in all cases, the main reaction path is the addition to the double bond of the aromatic ring followed by ring opening in the case of OH and NO3 radicals. The formation of 3-furaldehyde and hydroxy-methylfuranones (in the reactions of 3-methylfuran with Cl atoms and NO3 radicals) confirmed the H-atom abstraction from the methyl group and from the aromatic ring, respectively. This study represents the first product determination for Cl atoms and NO3 radicals in reactions with 3-methylfuran. The reaction mechanisms and atmospheric implications of the reactions under consideration are also discussed.
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Browne, E. C., P. J. Wooldridge, K. E. Min, and R. C. Cohen. "On the role of monoterpene chemistry in the remote continental boundary layer." Atmospheric Chemistry and Physics Discussions 13, no. 8 (August 27, 2013): 22297–335. http://dx.doi.org/10.5194/acpd-13-22297-2013.
Повний текст джерелаАнотація:
Abstract. The formation of organic nitrates (RONO2) represents an important NOx (NOx = NO + NO2) sink in remote and rural continental atmosphere thus impacting ozone production and secondary organic aerosol (SOA) formation. In these remote and rural environments, the organic nitrates are primarily derived from biogenic volatile organic compounds (BVOCs) such as isoprene and monoterpenes. Although there are numerous studies investigating the formation of SOA from monoterpenes, there are few studies investigating monoterpene gas phase chemistry. Using a regional chemical transport model with an extended representation of organic nitrate chemistry we investigate the processes controlling the production and fate of monoterpene nitrates (MTNs) over the boreal forest of Canada. MTNs account for 5–12% of total oxidized nitrogen over the boreal forest and production via NO3 chemistry is more important than production via OH when the NOx mixing ratio is greater than 75 pptv. The regional responses are investigated for two oxidation pathways of MTNs: one that returns NOx to the atmosphere and one that converts MTNs to a nitrate that behaves like HNO3. The likely situation is in between and these two assumptions bracket the uncertainty about this chemistry. In the case where the MTNs return NOx after oxidation, their formation represents a net chemical NOx loss that exceeds the net loss to peroxy nitrate formation. When oxidation of MTNs produces a molecule that behaves like HNO3, HNO3 and MTNs are nearly equal chemical sinks for NOx. This uncertainty in the oxidative fate of MTNs results in changes in NOx of 8–14%, in O3 of up to 3%, and in OH of 3–6% between the two model simulations.
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Browne, E. C., P. J. Wooldridge, K. E. Min, and R. C. Cohen. "On the role of monoterpene chemistry in the remote continental boundary layer." Atmospheric Chemistry and Physics 14, no. 3 (February 3, 2014): 1225–38. http://dx.doi.org/10.5194/acp-14-1225-2014.
Повний текст джерелаАнотація:
Abstract. The formation of organic nitrates (RONO2) represents an important NOx (NOx = NO + NO2) sink in the remote and rural continental atmosphere, thus impacting ozone production and secondary organic aerosol (SOA) formation. In these remote and rural environments, the organic nitrates are primarily derived from biogenic volatile organic compounds (BVOCs) such as isoprene and monoterpenes. Although there are numerous studies investigating the formation of SOA from monoterpenes, there are few studies investigating monoterpene gas-phase chemistry. Using a regional chemical transport model with an extended representation of organic nitrate chemistry, we investigate the processes controlling the production and fate of monoterpene nitrates (MTNs) over the boreal forest of Canada. MTNs account for 5–12% of total oxidized nitrogen over the boreal forest, and production via NO3 chemistry is more important than production via OH when the NOx mixing ratio is greater than 75 pptv. The regional responses are investigated for two oxidation pathways of MTNs: one that returns NOx to the atmosphere and one that converts MTNs into a nitrate that behaves like HNO3. The likely situation is in between, and these two assumptions bracket the uncertainty about this chemistry. In the case where the MTNs return NOx after oxidation, their formation represents a net chemical NOx loss that exceeds the net loss to peroxy nitrate formation. When oxidation of MTNs produces a molecule that behaves like HNO3, HNO3 and MTNs are nearly equal chemical sinks for NOx. This uncertainty in the oxidative fate of MTNs results in changes in NOx of 8–14%, in O3 of up to 3%, and in OH of 3–6% between the two model simulations.
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Bialek, J., M. Dall Osto, P. Vaattovaara, S. Decesari, J. Ovadnevaite, A. Laaksonen, and C. O'Dowd. "Hygroscopic and chemical characterisation of Po Valley aerosol." Atmospheric Chemistry and Physics 14, no. 3 (February 12, 2014): 1557–70. http://dx.doi.org/10.5194/acp-14-1557-2014.
Повний текст джерелаАнотація:
Abstract. Continental summer-time aerosol in the Italian Po Valley was characterised in terms of hygroscopic properties and the influence of chemical composition therein. Additionally, the ethanol affinity of particles was analysed. The campaign-average minima in hygroscopic growth factors (HGFs, at 90% relative humidity) occurred just before and during sunrise from 03:00 to 06:00 LT (all data are reported in the local time), but, more generally, the hygroscopicity during the whole night is very low, particularly in the smaller particle sizes. The average HGFs recorded during the low HGF period were in a range from 1.18 (for the smallest, 35nm particles) to 1.38 (for the largest, 165 nm particles). During the day, the HGF gradually increased to achieve maximum values in the early afternoon hours 12:00–15:00, reaching 1.32 for 35 nm particles and 1.46 for 165 nm particles. Two contrasting case scenarios were encountered during the measurement period: Case 1 was associated with westerly air flow moving at a moderate pace and Case 2 was associated with more stagnant, slower moving air from the north-easterly sector. Case 1 exhibited weak diurnal temporal patterns, with no distinct maximum or minimum in HGF or chemical composition, and was associated with moderate non-refractory aerosol mass concentrations (for 50% size cut at 1 μ) of the order of 4.5 μg m−3. For Case 1, organics contributed typically 50% of the mass. Case 2 was characterised by >9.5 μg m−3 total non-refractory mass (<1 μ) in the early morning hours (04:00), decreasing to ~3 μg m−3 by late morning (10:00) and exhibited strong diurnal changes in chemical composition, particularly in nitrate mass but also in total organic mass concentrations. Specifically, the concentrations of nitrate peaked at night-time, along with the concentrations of hydrocarbon-like organic aerosol (HOA) and of semi-volatile oxygenated organic aerosol (SV-OOA). In general, organic growth factors (OGFs) followed a trend which was opposed to HGF and also to the total organic mass as measured by the aerosol mass spectrometer. The analysis of the HGF probability distribution function (PDF) reveals an existence of a predominant "more hygroscopic" (MH) mode with HGF of 1.5 around noon, and two additional modes: one with a "less hygroscopic" (LH) HGF of 1.26, and another with a "barely hygroscopic" (BH) mode of 1.05. Particles sized 165 nm exhibited moderate diurnal variability in HGF, ranging from 80% at night to 95% of "more hygroscopic" growth factors (i.e. HGFs 1.35–1.9) around noon. The diurnal changes in HGF progressively became enhanced with decreasing particle size, decreasing from 95% "more hygroscopic" growth factor fraction at noon to 10% fraction at midnight, while the "less hygroscopic" growth factor fraction (1.13–1.34) increased from 5% at noon to > 60% and the "barely hygroscopic" growth factor fraction (1.1–1.2) increased from less than 2% at noon to 30% at midnight. Surprisingly, the lowest HGFs occurred for the period when nitrate mass reached peak concentrations (Case 2). We hypothesised that the low HGFs of nitrate-containing particles can be explained by a) an organic coating suppressing the water-uptake, and/or by b) the existence of nitrates in a less hygroscopic state, e.g. as organic nitrates. The latter hypothesis allows us to explain also the reduced OGFs observed during the early morning hours (before dawn) when nitrate concentrations peaked, based on the evidence that organic nitrates have significant lower ethanol affinity than other SV-OOA compounds.
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Rinaudo, J. D., C. Arnal, R. Blanchin, P. Elsass, A. Meilhac, and S. Loubier. "Assessing the cost of groundwater pollution: the case of diffuse agricultural pollution in the Upper Rhine valley aquifer." Water Science and Technology 52, no. 9 (November 1, 2005): 153–62. http://dx.doi.org/10.2166/wst.2005.0308.
Повний текст джерелаАнотація:
This paper presents an assessment of the costs of diffuse groundwater pollution by nitrates and pesticides for the industrial and the drinking water sectors in the Upper Rhine valley, France. Pollution costs which occurred between 1988 and 2002 are described and assessed using the avoidance cost method. Geo-statistical methods (kriging) are then used to construct three scenarios of nitrate concentration evolution. The economic consequences of each scenario are then assessed. The estimates obtained are compared with the results of a contingent valuation study carried out in the same study area ten years earlier.
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García-Linares, C., M. Martínez-Santos, V. Martínez-Bilbao, J. M. Sánchez-Pérez, and I. Antiguedad. "Wetland restoration and nitrate reduction: the example of the peri-urban wetland of Vitoria-Gasteiz (Basque Country, North Spain)." Hydrology and Earth System Sciences 7, no. 1 (February 28, 2003): 109–21. http://dx.doi.org/10.5194/hess-7-109-2003.
Повний текст джерелаАнотація:
Abstract. Changes in land use and agricultural intensification caused wetlands on the quaternary aquifer of Vitoria-Gasteiz (Basque Country) to disappear some years ago and nitrate concentration in groundwaters increased very quickly. The Basque Government recently declared the East Sector of this aquifer a Vulnerable Zone according to the 91/676/CEE European Directive. Recently, the wetlands have been restored through the closure of the main drainage ditches, the consequent elevation of the water table and the abondonment of agricultural practices near the wetlands. This is the case of the Zurbano wetland. Restoration has allowed the recovery of its biogeochemical function, which has reduced nitrate concentrations in waters. Nitrate concentrations which exceed 50 mg l–1 in groundwaters entering into the wetland are less than 10 mg l–1 at the outlet. Conditions in the wetland are conducive to the loss of nitrates: organic matter rich wetted soils, clay presence allowing a local semiconfined flow and very low hydraulic gradient. Water quality monitoring at several points around the wetland showed the processes involved in nitrate loss, although some aspects still remain unresolved. However, during storm events, the wetland effectively reduces the nitrate concentration entering the Alegria River, the most important river on the quaternary aquifer. Keywords: restored wetland functionality, nitrate losses, Basque Country
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Moldovan, Ana, Maria-Alexandra Hoaghia, Eniko Kovacs, Ionuț Cornel Mirea, Marius Kenesz, Răzvan Adrian Arghir, Alexandru Petculescu, Erika Andrea Levei, and Oana Teodora Moldovan. "Quality and Health Risk Assessment Associated with Water Consumption—A Case Study on Karstic Springs." Water 12, no. 12 (December 14, 2020): 3510. http://dx.doi.org/10.3390/w12123510.
Повний текст джерелаАнотація:
In rural areas without centralized water supply systems, inhabitants often use groundwater of unknown quality as drinking water, without understanding the possible negative consequences on their health. Karstic spring waters from Dobrogea region in Romania were assessed for their potential to be used as drinking water source, according to their quality and seasonal variation. The physico-chemical parameters of waters were compared with the guideline values for drinking water established by the World Health Organization and the Directive 98/83/EC. The nitrate and Cr concentrations exceeded the guideline value in the springs from Southern Dobrogea, but met the quality criteria in those from Northern Dobrogea, thus, to be used as drinking water, the karstic springs located in Southern Dobrogea require treatment for nitrates removal. Heavy metals pollution indices showed low to medium cumulative heavy metal pollution in all springs, while the human health risk assessment by oral exposure indicated possible noncarcinogenic risks of nitrates, both for adults and children in springs from South Dobrogea. A rigorous monitoring of the water quality before human consumption is recommended for all four studied water sources.
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Patroescu, Ion Viorel, Ioana Alexandra Ionescu, Lucian Alexandru Constantin, Laurentiu Razvan Dinu, and Valeriu Robert Badescu. "Nitrate Removal from Groundwater by Denitrification in Fixed and Fluidized Bed Biofilm Reactors A Comparative Study." Revista de Chimie 70, no. 1 (February 15, 2019): 297–300. http://dx.doi.org/10.37358/rc.19.1.6903.
Повний текст джерелаАнотація:
The influence of attached biomass bioreactor types on the denitrification process using a low-pitched groundwater containing nitrates was studied. Two types of fixed-bed and fluidized-bed biofilm reactors, equipped with expanded clay granular filler, with a particle size fraction of 2-5 mm were used. The nitrite and nitrate concentrations in the inflow and outflow of the two bioreactors were analytically determined. Based on the obtained concentration values, the denitrification rates were calculated, ranging between 1275�1387 g NO3-N/m3/day in the case of the fixed bioreactor and between 3390�3867 g NO3-N/m3/day in the case of the fluidized bed bioreactor.
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Kołton, Anna, Renata Wojciechowska, and Maria Leja. "The effect of various light conditions and different nitrogen forms on nitrogen metabolism in pepper fruits." Folia Horticulturae 24, no. 2 (December 1, 2012): 153–60. http://dx.doi.org/10.2478/v10245-012-0019-8.
Повний текст джерелаАнотація:
Abstract The ‘Spartacus’ F1 sweet pepper was grown in a plastic tunnel on rockwool during 2006-2008. A fertigation technique was used for water and fertiliser application. The tunnel was divided into two parts covered with different plastic films. The first part of the tunnel was covered with a film that transmitted less light than the film covering the second part. In both parts of the tunnel, the plants were divided into two groups. One group of plants was fertilised with just nitrate nitrogen (100% N-NO3) and the other one with three forms of nitrogen (N-NO3:N-NH4:N-NH2 in a ratio of 50:13:37). Fruits were harvested mature green and red. Concentrations of nitrate and ammonium ions as well as total nitrogen and free amino acids were analysed in the plant material. Nitrate and nitrite reductase activities were also investigated, and dry matter content and soluble sugars were also determined. Higher light intensity increased nitrate concentration in red pepper fruits but decreased ammonium ion content. These tendencies were not as obvious in green fruits. In most cases, red fruits fertilised with three nitrogen forms accumulated more nitrates than those fertilised with N-NO3. This observation was similar in the case of green fruits. In most cases, pepper fruits accumulated more ammonium ions in the case of N-NO3 fertilisation than when three forms of nitrogen were applied, but the differences were not always statistically significant. Higher nitrate reductase activity was observed in the case of better light conditions as well as mixed nitrogen fertilisation in red pepper fruits. No differences were observed in the case of nitrite reductase activity between fruits harvested from various treatments in red and also green fruits, with some exceptions. The green fruits of pepper had higher nitrate reductase activity than the red ones. It can be summarised that various light conditions influenced the nitrogen metabolism of pepper fruits as well as the different nitrogen forms applied with fertilisers.
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Colmenar, Inmaculada, Pilar Martin, Beatriz Cabañas, Sagrario Salgado, Araceli Tapia, and Inmaculada Aranda. "Atmospheric fate of a series of saturated alcohols: kinetic and mechanistic study." Atmospheric Chemistry and Physics 20, no. 2 (January 21, 2020): 699–720. http://dx.doi.org/10.5194/acp-20-699-2020.
Повний текст джерелаАнотація:
Abstract. The atmospheric fate of a series of saturated alcohols (SAs) was evaluated through kinetic and reaction product studies with the main atmospheric oxidants. These SAs are alcohols that could be used as fuel additives. Rate coefficients (in cm3 molecule−1 s−1) measured at ∼298 K and atmospheric pressure (720±20 Torr) were as follows: k1 ((E)-4-methylcyclohexanol + Cl) = (3.70±0.16) ×10-10, k2 ((E)-4-methylcyclohexanol + OH) = (1.87±0.14) ×10-11, k3 ((E)-4-methylcyclohexanol + NO3) = (2.69±0.37) ×10-15, k4 (3,3-dimethyl-1-butanol + Cl) = (2.69±0.16) ×10-10, k5 (3,3-dimethyl-1-butanol + OH) = (5.33±0.16) ×10-12, k6 (3,3-dimethyl-2-butanol + Cl) = (1.21±0.07) ×10-10, and k7 (3,3-dimethyl-2-butanol + OH) = (10.50±0.25) ×10-12. The main products detected in the reaction of SAs with Cl atoms (in the absence/presence of NOx), OH radicals, and NO3 radicals were (E)-4-methylcyclohexanone for the reactions of (E)-4-methylcyclohexanol, 3,3-dimethylbutanal for the reactions of 3,3-dimethyl-1-butanol, and 3,3-dimethyl-2-butanone for the reactions of 3,3-dimethyl-2-butanol. Other products such as formaldehyde, 2,2-dimethylpropanal, and acetone have also been identified in the reactions of Cl atoms and OH radicals with 3,3-dimethyl-1-butanol and 3,3-dimethyl-2-butanol. In addition, the molar yields of the reaction products were estimated. The products detected indicate a hydrogen atom abstraction mechanism at different sites on the carbon chain of alcohol in the case of Cl reactions and a predominant site in the case of OH and NO3 reactions, confirming the predictions of structure–activity relationship (SAR) methods. Tropospheric lifetimes (τ) of these SAs have been calculated using the experimental rate coefficients. Lifetimes are in the range of 0.6–2 d for OH reactions, 7–13 d for NO3 radical reactions, and 1–3 months for Cl atoms. In coastal areas, the lifetime due to the reaction with Cl decreases to hours. The calculated global tropospheric lifetimes, and the polyfunctional compounds detected as reaction products in this work, imply that SAs could contribute to the formation of ozone and nitrated compounds at local, regional, and even global scales. Therefore, the use of saturated alcohols as additives in diesel blends should be considered with caution.
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Tapia, A., F. Villanueva, M. S. Salgado, B. Cabañas, E. Martínez, and P. Martín. "Atmospheric degradation of 3-methylfuran: kinetic and products study." Atmospheric Chemistry and Physics Discussions 10, no. 10 (October 5, 2010): 22905–52. http://dx.doi.org/10.5194/acpd-10-22905-2010.
Повний текст джерелаАнотація:
Abstract. A study of the kinetics and products obtained from the reactions of 3-methylfuran with the main atmospheric oxidants has been performed. The rate coefficients for the gas-phase reaction of 3-methylfuran with OH and NO3 radicals have been determined at room temperature and atmospheric pressure (air and N2 as bath gases), using a relative method with different experimental techniques. The absolute rate coefficients obtained for these reactions were (in units cm3 molecule−1 s−1): kOH=(1.13±0.22)×10−10 and kNO3=(1.26±0.18)×10−11. These rate coefficients have been compared with those available in the literature. The products from the reaction of 3-methylfuran with OH, NO3 and Cl atoms in the absence and in the presence of NOx species have also been determined. The main reaction products obtained were chlorinated methylfuranones and hydroxy-methylfuranones for the reaction of 3-methylfuran with Cl atoms, 2-methylbutenedial, 3-methyl-2,5-furanodione and hydroxy-methylfuranones for the reaction of 3-methylfuran with OH and NO3 radicals and also nitrated compounds for the reaction with NO3 radicals. The results indicate that in all cases the main reaction path is the addition to the double bond of the aromatic ring followed by ring opening in the case of OH and NO3 radicals. The formation of 3-furaldehyde and hydroxy-methylfuranones (in the reactions of 3-methylfuran with Cl atoms and NO3 radicals) confirmed the H-atom abstraction from the methyl group and from the aromatic ring, respectively. This study represents the first product determination for both Cl atoms and the NO3 radical in reactions with 3-methylfuran. The reaction mechanisms and atmospheric implications of the reactions under consideration are also discussed.
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Campolo, Nicolás, Federico M. Issoglio, Darío A. Estrin, Silvina Bartesaghi, and Rafael Radi. "3-Nitrotyrosine and related derivatives in proteins: precursors, radical intermediates and impact in function." Essays in Biochemistry 64, no. 1 (February 2020): 111–33. http://dx.doi.org/10.1042/ebc20190052.
Повний текст джерелаАнотація:
Abstract Oxidative post-translational modification of proteins by molecular oxygen (O2)- and nitric oxide (•NO)-derived reactive species is a usual process that occurs in mammalian tissues under both physiological and pathological conditions and can exert either regulatory or cytotoxic effects. Although the side chain of several amino acids is prone to experience oxidative modifications, tyrosine residues are one of the preferred targets of one-electron oxidants, given the ability of their phenolic side chain to undergo reversible one-electron oxidation to the relatively stable tyrosyl radical. Naturally occurring as reversible catalytic intermediates at the active site of a variety of enzymes, tyrosyl radicals can also lead to the formation of several stable oxidative products through radical–radical reactions, as is the case of 3-nitrotyrosine (NO2Tyr). The formation of NO2Tyr mainly occurs through the fast reaction between the tyrosyl radical and nitrogen dioxide (•NO2). One of the key endogenous nitrating agents is peroxynitrite (ONOO−), the product of the reaction of superoxide radical (O2•−) with •NO, but ONOO−-independent mechanisms of nitration have been also disclosed. This chemical modification notably affects the physicochemical properties of tyrosine residues and because of this, it can have a remarkable impact on protein structure and function, both in vitro and in vivo. Although low amounts of NO2Tyr are detected under basal conditions, significantly increased levels are found at pathological states related with an overproduction of reactive species, such as cardiovascular and neurodegenerative diseases, inflammation and aging. While NO2Tyr is a well-established stable oxidative stress biomarker and a good predictor of disease progression, its role as a pathogenic mediator has been laboriously defined for just a small number of nitrated proteins and awaits further studies.
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Rinaldo, A., G. Botter, E. Bertuzzo, A. Uccelli, T. Settin, and M. Marani. "Transport at basin scales: 2. Applications." Hydrology and Earth System Sciences 10, no. 1 (February 8, 2006): 31–48. http://dx.doi.org/10.5194/hess-10-31-2006.
Повний текст джерелаАнотація:
Abstract. In this paper, the second of a series, we apply the models discussed in Part 1 to a significant case study. The nature of the catchment under study, the transport phenomena investigated (i.e. nitrates moving as solutes within runoff waters) and the scales involved in space and time, provide an elaborate test for theory and applications. Comparison of modeling predictions with field data (i.e. fluxes of carrier flow and solute nitrates) suggests that the framework proposed for geomorphic transport models is capable to describe well large-scale transport phenomena driven and/or controlled by spatially distributed hydrologic fields (e.g. rainfall patterns in space and time, drainage pathways, soil coverage and type, matter stored in immobile phases). A sample MonteCarlo mode of application of the model is also discussed where hydrologic forcings and external nitrate applications (through fertilization) are treated as random processes.
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Rinaldo, A., G. Botter, E. Bertuzzo, A. Uccelli, T. Settin, and M. Marani. "Transport at basin scales: 2. Applications." Hydrology and Earth System Sciences Discussions 2, no. 4 (August 23, 2005): 1641–81. http://dx.doi.org/10.5194/hessd-2-1641-2005.
Повний текст джерелаАнотація:
Abstract. In this paper, the second of a series, we apply the models discussed in Part 1 to a significant case study. The nature of the catchment under study, the transport phenomena investigated (i.e. nitrates moving as solutes within runoff waters) and the scales involved in space and time, provide an elaborate test for theory and applications. Comparison of modeling predictions with field data (i.e. fluxes of carrier flow and solute nitrates) suggests that the framework proposed for geomorphic transport models is capable to describe well large-scale transport phenomena driven and/or controlled by spatially distributed hydrologic fields (e.g. rainfall patterns in space and time, drainage pathways, soil coverage and type, matter stored in immobile phases). A sample MonteCarlo mode of application of the model is also discussed where hydrologic forcings and external nitrate applications (through fertilization) are treated as random processes.
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Clausen, Hannah S., Ninna H. Ebdrup, Ida M. Barsøe, Julie Lyngsø, Jörg Schullehner, Cecilia H. Ramlau-Hansen, Bjørn Bay, and Ulla B. Knudsen. "Association between Drinking Water Nitrate and Adverse Reproductive Outcomes: A Systematic PRISMA Review." Water 12, no. 8 (August 14, 2020): 2287. http://dx.doi.org/10.3390/w12082287.
Повний текст джерелаАнотація:
One in six couples experience fertility problems. Environmental factors may affect reproductive health; however, evidence is lacking regarding drinking water nitrates and outcomes of male and female fertility. The aim of this study was to investigate if exposure to nitrates in drinking water is associated with adverse reproductive outcomes in humans, and animals of fertile age. We conducted a systematic literature search and included case-control studies, cohort studies, and randomized control trials reporting on the association between drinking water nitrate exposure of men, women, or animals and adverse reproductive outcomes, specified as: Semen quality parameters, time to pregnancy (TTP), pregnancy rates, assisted reproductive technologies (ART), and spontaneous abortion. Findings were reported in a narrative synthesis. A total of 12 studies were included. The only human study included reported a decrease in spontaneous abortion at any detectable nitrate level. Overall, the 11 included animal studies support a potential negative effect on semen quality parameters but report equivocal results on TTP and number of offspring produced, and higher risk of spontaneous abortion. In conclusion, animal studies indicate possible effects on semen quality parameters and spontaneous abortion. However, with a few studies, including some with methodological limitations and small sample sizes, caution must be applied when interpreting these results.
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Jones, A. E., E. W. Wolff, D. Ames, S. J. B. Bauguitte, K. C. Clemitshaw, Z. Fleming, G. P. Mills, et al. "The multi-seasonal NO<sub>y</sub> budget in coastal Antarctica and its link with surface snow and ice core nitrate: results from the CHABLIS campaign." Atmospheric Chemistry and Physics 11, no. 17 (September 8, 2011): 9271–85. http://dx.doi.org/10.5194/acp-11-9271-2011.
Повний текст джерелаАнотація:
Abstract. Measurements of a suite of individual NOy components were carried out at Halley station in coastal Antarctica as part of the CHABLIS campaign (Chemistry of the Antarctic Boundary Layer and the Interface with Snow). Conincident measurements cover over half a year, from austral winter 2004 through to austral summer 2005. Results show clear dominance of organic NOy compounds (PAN and MeONO2) during the winter months, with low concentrations of inorganic NOy. During summer, concentrations of inorganic NOy compounds are considerably greater, while those of organic compounds, although lower than in winter, are nonetheless significant. The relative concentrations of the alkyl nitrates, as well as their seasonality, are consistent with an oceanic source. Multi-seasonal measurements of surface snow nitrate correlate strongly with inorganic NOy species (especially HNO3) rather than organic. One case study in August suggested that, on that occasion, particulate nitrate was the dominant source of nitrate to the snowpack, but this was not the consistent picture throughout the measurement period. An analysis of NOx production rates showed that emissions of NOx from the snowpack overwhelmingly dominate over gas-phase sources. This result suggests that, for certain periods in the past, the flux of NOx into the Antarctic boundary layer can be calculated from ice core nitrate data.
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Ptak, Emilia Noel, Morten Graversgaard, Jens Christian Refsgaard, and Tommy Dalgaard. "Nitrate Management Discourses in Poland and Denmark—Laggards or Leaders in Water Quality Protection?" Water 12, no. 9 (August 24, 2020): 2371. http://dx.doi.org/10.3390/w12092371.
Повний текст джерелаАнотація:
The most significant source of nitrate pollution in the European Union (EU) is attributed to agricultural activities, which threaten drinking water, marine, and freshwater resources. The Nitrates Directive is a key feature of the Water Framework Directive (WFD), which seeks to reduce nitrate pollution from agricultural sources. Yet, weak compliance by Member States (MS) diminishes the legitimacy of the EU environmental acquis and undermines efforts to achieve environmental objectives. This study examines the nitrate management discourse in Poland to identify influencing factors that impact governance capacity and overall compliance performance. The empirical investigation is based on nine stakeholder interviews, three written correspondences, and a literature review that collectively comprise an evaluation study. A comparison in governance approaches between Poland and Denmark provides a calibration in assessing performance respective to another MS. The findings categorize both Poland and Denmark as “laggard” in WFD compliance. This case contributes new insights in identifying 6 enabling and 13 constraining factors affecting the ability of MS to fulfill their implementation duties. The findings demonstrate that divergent stakeholder views based on historical and cultural norms require a differentiated approach tailored to domestic conditions for effective fulfillment of the objectives set forth in EU environmental legislation.
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Conte, Francesco, Veronica Pellegatta, Alessandro Di Michele, Gianguido Ramis, and Ilenia Rossetti. "Photocatalytic Reduction of Nitrates and Combined Photodegradation with Ammonium." Catalysts 12, no. 3 (March 11, 2022): 321. http://dx.doi.org/10.3390/catal12030321.
Повний текст джерелаАнотація:
Bare titania and metal-promoted TiO2 catalysts were employed in the treatment of nitrates, which are ubiquitous pollutants of wastewater. The results show that the process can be carried out under visible light (from a white light LED lamp) and, in the best case, 23.5% conversion of nitrate was obtained over 4 h with full selectivity towards N2 by employing 0.1 mol% Ag/TiO2 prepared by flame spray pyrolysis. Moreover, the performance was worse when testing the same catalysts with tap water (11.3% conversion), due to the more complex composition of the matrix. Finally, it was found that photoreduction of nitrate can be effectively performed in combination with photo-oxidation of ammonium without loss in the activity, opening up the possibility of treating highly polluted wastewater with a single process. The latter treatment employs the two contaminants simultaneously as electron and holes scavengers, with very good selectivity, in a completely new process that we may call Photo-Selective Catalytic Reduction (Photo-SCR).
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Živančev, Nevena, Srđan Kovačević, Marija Perović, Aleksandar Čalenić, and Milan Dimkić. "Influence of oxic and anoxic groundwater conditions on occurrence of selected agrochemicals." Water Supply 20, no. 2 (December 5, 2019): 487–98. http://dx.doi.org/10.2166/ws.2019.178.
Повний текст джерелаАнотація:
Abstract The occurrence and mitigation of selected pesticides and nitrates in surface and groundwater samples from two alluvions in the Republic of Serbia are investigated in this study. The influence of aquifer conditions on the degradation processes of pesticides and nitrates is considered as a potential removal mechanism of compound residues in alluvial groundwater. Nitrate concentration was analyzed in 144 groundwater samples in the Kovin-Dubovac drainage system and 63 samples at the Ključ groundwater source. The occurrence of 15 pesticides was monitored in groundwater in a total of 34 samples in the Kovin-Dubovac area and 14 samples at the Ključ groundwater source. Concentrations of selected pesticides and nitrates were monitored in eight samples from the Danube in the Kovin-Dubovac area and 15 samples from Velika Morava at the Ključ groundwater source. Both selected locations are agricultural areas. Results show that concentrations of nitrates (NO3−) are much higher in oxic groundwater conditions compared with concentrations in typical anoxic conditions. The opposite is the case for the concentration of pesticides that occurred in surface and groundwater samples. These results are very important for a better understanding of the self-purification potential of alluvial aquifers and assessment of aquifer condition influence, especially oxic or anoxic conditions, on the occurrence and mitigation of selected agrochemical residues in groundwaters.
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Nocuń-Wczelik, Wiesława, and Barbara Trybalska. "Scanning Electron Microscopy in the Studies of Hydrated Cementitious Materials Microstructure Formed in the Presence of some Heavy Metals Containing Admixtures." Solid State Phenomena 231 (June 2015): 145–53. http://dx.doi.org/10.4028/www.scientific.net/ssp.231.145.
Повний текст джерелаАнотація:
The calorimetric measurements together with microscopic observations and analyses relating to the interaction of cement paste with sulfate and nitrate solutions of various concentration were carried out. These salts modify the rate of cement hydration at early age. In the presence of sulfates the formation of some well crystallized calcium sulfates or calcium sulfoaluminates can be found. In case of nitrates there is no additional products. However, one can observe that the calcium silicate phase becomes less fibrous but more compact, with very small individual particles, as the nucleation from the liquid phase is disturbed. There are the accompanying cations incorporated in this product.
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Podunavac-Kuzmanovic, Sanja, and Ljiljana Vojinovic. "Synthesis and physico-chemical characterization of zinc(II), nickel(II) and cobalt(II) complexes with 2-phenyl-2-imidazoline." Acta Periodica Technologica, no. 34 (2003): 119–24. http://dx.doi.org/10.2298/apt0334119p.
Повний текст джерелаАнотація:
Chlorides and nitrates of zinc(II), nickel(II) and cobalt(II) react with 2-phenyl-2-imidazoline to give complexes of the type [ML2X2]?nH2O (M=Zn, Ni or Co; L=2-phenyl-2-imidazoline; X=Cl or NO3; n=0, 1 or 2). The complexes were synthesized and characterized by elemental analysis of the metal molar conductivity, magnetic susceptibility measurements and IR spectra. The molar conductances of the zinc(II) complexes in DMF solutions indicate that the complexes behave as non-electrolytes. The values of magnetic conductivity in the case of nickel(II) complexes indicate that one of the coordinated anions (chloride or nitrate) has been replaced by DMF molecule. The molar conductivity values of cobalt(II) complexes indicate the partial substitution of coordinated anions with solvent molecules. The room temperature effective magnetic moments and IR data of the complexes suggest that all Zn(II), Ni(II) and Co(II) complexes have a tetrahedral configuration, which is realized by participation of the pyridine nitrogen of two organic ligand molecules, and two chloride or nitrate anions typical for these classes of organic ligands.
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Paschalidis, Damianos G., and William T. A. Harrison. "Two mixed-ligand lanthanide–hydrazone complexes: [Pr(NCS)3(pbh)2]·H2O and [Nd(NCS)(NO3)(pbh)2(H2O)]NO3·2.33H2O [pbh isN′-(pyridin-2-ylmethylidene)benzohydrazide, C13H11N3O]." Acta Crystallographica Section E Crystallographic Communications 72, no. 2 (January 16, 2016): 191–95. http://dx.doi.org/10.1107/s2056989015024962.
Повний текст джерелаАнотація:
The gel-mediated syntheses and crystal structures of [N′-(pyridin-2-ylmethylidene-κN)benzohydrazide-κ2N′,O]tris(thiocyanato-κN)praseodymium(III) monohydrate, [Pr(NCS)3(C13H11N3O)2]·H2O, (I), and aqua(nitrato-κ2O,O′)[N′-(pyridin-2-ylmethylidene-κN)benzohydrazide-κ2N′,O](thiocyanato-κN)neodymium(III) nitrate 2.33-hydrate, [Nd(NCS)(NO3)(C13H11N3O)2(H2O)]NO3·2.33H2O, (II), are reported. The Pr3+ion in (I) is coordinated by twoN,N,O-tridentateN′-(pyridin-2-ylmethylidene)benzohydrazide (pbh) ligands and threeN-bonded thiocyanate ions to generate an irregular PrN7O2coordination polyhedron. The Nd3+ion in (II) is coordinated by twoN,N,O-tridentate pbh ligands, anN-bonded thiocyanate ion, a bidentate nitrate ion and a water molecule to generate a distorted NdN5O5bicapped square antiprism. The crystal structures of (I) and (II) feature numerous hydrogen bonds, which lead to the formation of three-dimensional networks in each case.
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Korotaeva, Anna. "Wastewater treatment of mining enterprises from nitrogen compounds in the Arctic." SHS Web of Conferences 84 (2020): 04001. http://dx.doi.org/10.1051/shsconf/20208404001.
Повний текст джерелаАнотація:
Open pit mining using explosives based on ammonium nitrate leads to wastewater pollution with nitrogen compounds. In case of insufficient wastewater treatment, pollutants enter surface-water bodies. Excessive concentration of nitrogen compounds in water leads to the development of the process of eutrophication, which adversely affects the vital activity of aquatic organisms and humans. At the moment, a common method of wastewater treatment from nitrogen compounds is a biological treatment method using devices such as aeration chambers, oxidation tanks and slim filters. An alternative option for biological treatment is the introduction of algae into wastewater. In the conditions of the Arctic, it is difficult to carry out biological treatment using algae due to low temperatures throughout the year. In this study, the feasibility of using the frost-resistant strain Chlorella kessleri VKPM A1-l1ARW for the effluents treatment from nitrogen compounds was tested. Model solutions with a known nitrates concentration were used. Experiments were carried out at two specified temperatures for comparison. The results showed that by the end of the 10-day experiment, the nitrates extraction efficiency at standard temperature (20 °C) was from 40.3% to 71.8%, at low temperature (3 °C) was from 30.4% to 73.6%.
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Wille, Uta, and Catrin Goeschen. "Oxidative Damage of Thymidines by the Atmospheric Free-Radical Oxidant NO3•." Australian Journal of Chemistry 64, no. 6 (2011): 833. http://dx.doi.org/10.1071/ch11102.
Повний текст джерелаАнотація:
Analysis of the products formed in the reaction of nitrate radicals, NO3 •, with the N- and O-methylated and acetylated thymidines 1a and 1b revealed, for the first time, insight regarding how this important atmospheric free-radical oxidant can cause irreversible damage to DNA building blocks. Mechanistic studies indicated that the initial reaction step likely proceeds via NO3 • induced electron transfer at the pyrimidine ring, followed by deprotonation of the methyl group at C5. The oxidation ultimately leads to formation of nitrates 2, aldehydes 4 and, in the case of high [NO3 •], also to carboxylic acids 5. In addition to this, through a very minor pathway, loss of the methyl group at C5 also occurred to give the respective 2′-deoxyuridines 6. The nitrates 2 are highly labile compounds that undergo rapid hydrolysis during work-up and purification of the reaction mixtures, which could lead to serious misinterpretation of the experimental findings and reaction mechanism. Products resulting from NO3 • addition to the C5=C6 double bond in the pyrimidine ring were not observed. Also, no reaction of NO3 • with the 2′-deoxyribose moiety was detected.
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Archer, J. "Avoiding pollution from poultry manure." World's Poultry Science Journal 49, no. 2 (July 1993): 167–70. http://dx.doi.org/10.1079/wps19930014.
Повний текст джерелаАнотація:
In the UK the poultry industry has a good record with regard to surface water contamination and has been responsible for only a small proportion of the total pollution incidents attributable to agriculture. Guidance is provided to farmers by a Code of Good Agricultural Practice for the Protection of Water. Because poultry manures have high concentrations of total nitrogen, with much of this in soluble form, the pollution of ground water with nitrates is a more serious problem. A voluntary Pilot Nitrate Scheme has been introduced in some parts of the UK which controls the quantities of animal waste applied to the land and also the timing of waste application. Linked to the scheme is a comprehensive programme of scientific monitoring. The broad requirements of the European Community Nitrate Directive are described. In the case of air pollution due to odours, poultry farms were reported to be responsible for 17% of complaints attributed to agriculture. Where appropriate, legislative means exist to reduce the nuisance and a Code of Good Agricultural Practice for the Protection of Air has been published. Some implications for poultry production in the future are considered.
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Toma, Shino, Steve Bertman, Christopher Groff, Fulizi Xiong, Paul B. Shepson, Paul Romer, Kaitlin Duffey, et al. "Importance of biogenic volatile organic compounds to acyl peroxy nitrates (APN) production in the southeastern US during SOAS 2013." Atmospheric Chemistry and Physics 19, no. 3 (February 12, 2019): 1867–80. http://dx.doi.org/10.5194/acp-19-1867-2019.
Повний текст джерелаАнотація:
Abstract. Gas-phase atmospheric concentrations of peroxyacetyl nitrate (PAN), peroxypropionyl nitrate (PPN), and peroxymethacryloyl nitrate (MPAN) were measured on the ground using a gas chromatograph electron capture detector (GC-ECD) during the Southern Oxidants and Aerosols Study (SOAS) 2013 campaign (1 June to 15 July 2013) in Centreville, Alabama, in order to study biosphere–atmosphere interactions. Average levels of PAN, PPN, and MPAN were 169, 5, and 9 pptv, respectively, and the sum accounts for an average of 16 % of NOy during the daytime (10:00 to 16:00 local time). Higher concentrations were seen on average in air that came to the site from the urban NOx sources to the north. PAN levels were the lowest observed in ground measurements over the past two decades in the southeastern US. A multiple regression analysis indicates that biogenic volatile organic compounds (VOCs) account for 66 % of PAN formation during this study. Comparison of this value with a 0-D model simulation of peroxyacetyl radical production indicates that at least 50 % of PAN formation is due to isoprene oxidation. MPAN has a statistical correlation with isoprene hydroxynitrates (IN). Organic aerosol mass increases with gas-phase MPAN and IN concentrations, but the mass of organic nitrates in particles is largely unrelated to MPAN.
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Bahadori, Elnaz, Francesco Conte, Antonio Tripodi, Gianguido Ramis, and Ilenia Rossetti. "Photocatalytic Selective Oxidation of Ammonia in a Semi-Batch Reactor: Unravelling the Effect of Reaction Conditions and Metal Co-Catalysts." Catalysts 11, no. 2 (February 5, 2021): 209. http://dx.doi.org/10.3390/catal11020209.
Повний текст джерелаАнотація:
Photocatalysis has been used for the oxidation of ammonia/ammonium in water. A semibatch photoreactor was developed for this purpose, and nanostructured TiO2-based materials, either commercial P25 or prepared by flame spray pyrolysis (FSP), were used as catalysts. In the present work, we investigated the effect of (i) metal co-catalysts, (ii) pH, and (iii) ammonia concentration on the efficiency of oxidation and on the selectivity to the undesired overoxidation byproduct, i.e., nitrites and nitrates. Several metals were added to both titania samples, and the physicochemical properties of every sample were studied by XRD, BET, and UV-Vis spectroscopy. The pH, which was investigated in the range of 2.5–11.5, was the most important parameter. The optimum pH values, resulted as 11.5 and 4.8 for P25 and FSP respectively, matching the best compromise between an acceptable conversion and a limited selectivity toward nitrite and nitrate formation. For both titania samples (P25 and FSP), ammonia conversion vs. nitrite and nitrate formation were highly dependent on the pH. At pH ≥ 9, the initial rate of photooxidation was high, with selective formation of overoxidized byproducts, whereas, at a more acidic pH, the conversion was lower, but the selectivity toward nitrogen formation was higher. P25 samples added with noble metal co-catalysts (0.1 mol% Ag, Au, Pd, Pt) at pH = 11.5 remarkably increased the selectivity to nitrite and nitrate, while, in the case of FSP samples (pH = 4.8), the co-catalysts increased the selectivity toward N2 with respect to the unpromoted catalyst and also the conversion in the case of Au and Pt. Reactivity was discussed, leading to the proposing of a mechanism that correlates the activity with either surface adsorption (depending of the surface charge of the catalyst and on pH) or the homogeneous reactivity of oxidizing species.