Base de dados : MEDLINE
Pesquisa : D01.625.062 [Categoria DeCS]
Referências encontradas : 1523 [refinar]
Mostrando: 1 .. 10   no formato [Longo]

página 1 de 153 ir para página                         

  1 / 1523 MEDLINE  
              next record last record
seleciona
para imprimir
Fotocópia
PMID:29431332
Autor:Iakubova IS; Dadaly YV; Mel'tser AV; Alikbayeva LA; Zhirnov AY; Andreyeva MA; Gorshkova MP; Antonova MS
Título:[Methodical issues of the monitoring for ammonium in indoors air].
Fonte:Gig Sanit; 95(10):917-22, 2016.
ISSN:0016-9900
País de publicação:Russia (Federation)
Idioma:rus
Resumo:Introduction. To perform mass studies of the indoors air environment of the ammonium content the actual issues are the shortening of the sampling time and material costs for their implementation, reduction of adverse effects of ammonium with keeping of the objectivity of results. Aim. The elaboration of the method of short-term air sampling for indoors ammonium and comparative assessment ofdifferent methods of sampling in the course of modeling and field tests. Materials and Methods. Air sampling for ammonium was carried out according to the developed program and standard method, under the average daily 4-fold taking according to State Standards (GOST) 17.2.3.01-86 andRD 52.04.186-89. The evaluation of the significance of deviations of analysis results was carried out in accordance with GOST R ISO 5725-6-2002 and Recommendations of the Interstate Standardization RMG - 61-2003. Results. There were executed model and field tests of air sampling for ammonium according to the standard method and the program of short-term sampling. There were obtained significantly comparable results of ammonium content in the indoor air in the course of model and field tests. Conclusions. Sampling according to the developed program has a number of advantages, including: the shortening of sampling time, material costs, increasing in productivity in the analysis of indoor airfor the ammonium content. The execution oftest sampling according to the developed program allows to reduce the time of ammonium exposure to personnel carrying out the test sampling.
Tipo de publicação: JOURNAL ARTICLE
Nome de substância:0 (Air Pollutants); 0 (Ammonium Compounds)


  2 / 1523 MEDLINE  
              first record previous record next record last record
seleciona
para imprimir
Fotocópia
Texto completo
PMID:28278777
Autor:Lu YF; Ma LJ; Ma L; Shan B; Chang JJ
Endereço:a School of Ecology and Environmental Science, Yunnan University , Kunming , People's Republic of China.
Título:Improvement of start-up and nitrogen removal of the anammox process in reactors inoculated with conventional activated sludge using biofilm carrier materials.
Fonte:Environ Technol; 39(1):59-67, 2018 Jan.
ISSN:0959-3330
País de publicação:England
Idioma:eng
Resumo:The start-up of the anaerobic ammonium oxidation (anammox) process in three up-flow column reactors seeded with common mixed activated sludge and added with three materials, sponge (R1), sponge + volcanic rock (R2) and sponge + charcoal (R3), as carriers for biofilm formation were comparatively investigated in this study. The supplement of volcanic rock and charcoal could significantly shorten the start-up time of the anammox process, which primarily occurred in the activity-enhanced phase, with ammonium and nitrite removal efficiencies stabilized above 92.5% and 93.4% after an operation period of 145, 105 and 121 d for R1, R2 and R3, respectively. After the successful anammox start-up, R2 performed significantly better in TN removal (p < .05), achieving an average rate of 91.0% and 191.5 g N m d compared to R1 of 88.4% and 172.1 g N m d , and R3 of 89.9% and 180.1 g N m d in the steady running phase. The ratios of consumed [Formula: see text] and generated [Formula: see text]/consumed [Formula: see text] after anammox start-up were lower than the theoretical values, probably suggesting the simultaneous existences of anammox, denitrification as well as nitrification processes in the reactors. A reddish brown biofilm was wrapped on the carriers and morphological detection of biofilm displayed the presentations of thick and compact floc aggregates and some filamentous bacteria on the sponge, and spherical-, ovoid- and shortrod-shaped microorganisms on the volcanic rock and charcoal. Using porous material as carrier for biofilm development is an effective strategy for practical application of the anammox reactor.
Tipo de publicação: JOURNAL ARTICLE
Nome de substância:0 (Ammonium Compounds); 0 (Nitrites); 0 (Sewage); 0 (Water Pollutants, Chemical); 16291-96-6 (Charcoal); N762921K75 (Nitrogen)


  3 / 1523 MEDLINE  
              first record previous record next record last record
seleciona
para imprimir
Fotocópia
Texto completo
PMID:29323112
Autor:Pflüger T; Hernández CF; Lewe P; Frank F; Mertens H; Svergun D; Baumstark MW; Lunin VY; Jetten MSM; Andrade SLA
Endereço:Institute for Biochemistry, University of Freiburg, Albertstr. 21, Freiburg, 79104, Germany.
Título:Signaling ammonium across membranes through an ammonium sensor histidine kinase.
Fonte:Nat Commun; 9(1):164, 2018 01 11.
ISSN:2041-1723
País de publicação:England
Idioma:eng
Resumo:Sensing and uptake of external ammonium is essential for anaerobic ammonium-oxidizing (anammox) bacteria, and is typically the domain of the ubiquitous Amt/Rh ammonium transporters. Here, we report on the structure and function of an ammonium sensor/transducer from the anammox bacterium "Candidatus Kuenenia stuttgartiensis" that combines a membrane-integral ammonium transporter domain with a fused histidine kinase. It contains a high-affinity ammonium binding site not present in assimilatory Amt proteins. The levels of phosphorylated histidine in the kinase are coupled to the presence of ammonium, as conformational changes during signal recognition by the Amt module are transduced internally to modulate the kinase activity. The structural analysis of this ammonium sensor by X-ray crystallography and small-angle X-ray-scattering reveals a flexible, bipartite system that recruits a large uptake transporter as a sensory module and modulates its functionality to achieve a mechanistic coupling to a kinase domain in order to trigger downstream signaling events.
Tipo de publicação: JOURNAL ARTICLE; RESEARCH SUPPORT, NON-U.S. GOV'T
Nome de substância:0 (Ammonium Compounds); 0 (Bacterial Proteins); 0 (Membrane Transport Proteins); EC 2.7.13.1 (Histidine Kinase)


  4 / 1523 MEDLINE  
              first record previous record next record last record
seleciona
para imprimir
Fotocópia
Texto completo
PMID:29311523
Autor:Uyama M; Inoue K; Kinoshita K; Miyahara R; Yokoyama H; Nakano M
Endereço:Shiseido Global Innovation Center.
Título:Effect of Dialkyl Ammonium Cationic Surfactants on the Microfluidity of Membranes Containing Raft Domains.
Fonte:J Oleo Sci; 67(1):67-75, 2018.
ISSN:1347-3352
País de publicação:Japan
Idioma:eng
Resumo:It has been reported that a lot of receptors localize in lipid raft domains and that the microfluidity of these domains regulates the activation of these receptors. In this study, we focused on the lipid raft and in order to evaluate the physicochemical effects of surfactants on microfluidity of lipid membranes, we used liposomes comprising of egg-yolk L-α-phosphatidylcholine, egg-yolk sphingomyelin, and cholesterol as a model of cell membranes containing raft domains. The microfluidity of the domains was characterized by fluorescence spectrometry using 1,6-diphenyl-1,3,5-hexatriene and 2-dimethylamino-6-lauroylnaphthalene. Among several surfactants, dialkylammonium-type cationic surfactants most efficiently increased the microfluidity. It is therefore concluded that (1) the electrostatic interaction between the cationic surfactant and eggPC/eggSM/cholesterol liposome could be important, (2) surfactants with alkyl chains more effectively inserted into membranes than those with acyl chains, and (3) cationic surfactants with lower T values have a greater ability to increase the fluidity.
Tipo de publicação: JOURNAL ARTICLE
Nome de substância:0 (Ammonium Compounds); 0 (Cations); 0 (Liposomes); 0 (Membrane Lipids); 0 (Phosphatidylcholines); 0 (Sphingomyelins); 0 (Surface-Active Agents); 97C5T2UQ7J (Cholesterol)


  5 / 1523 MEDLINE  
              first record previous record next record last record
seleciona
para imprimir
Fotocópia
Texto completo
PMID:29354835
Autor:Avilés-Moreno JR; Berden G; Oomens J; Martínez-Haya B
Endereço:Department of Physical, Chemical and Natural Systems, Universidad Pablo de Olavide, E-41013 Seville, Spain. bmarhay@upo.es.
Título:Guanidinium/ammonium competition and proton transfer in the interaction of the amino acid arginine with the tetracarboxylic 18-crown-6 ionophore.
Fonte:Phys Chem Chem Phys; 20(6):4067-4073, 2018 Feb 07.
ISSN:1463-9084
País de publicação:England
Idioma:eng
Resumo:The recognition of arginine plays a central role in modern proteomics and genomics. Arginine is unique among natural amino acids due to the high basicity of its guanidinium side chain, which sustains specific interactions and proton exchange biochemical processes. The search for suitable macrocyclic ionophores constitutes a promising route towards the development of arginine receptors. This study evaluates the conformational features involved in the binding of free arginine by the polyether macrocycle (18-crown-6)-tetracarboxylic acid. Infrared action vibrational spectroscopy and quantum-chemical computations are combined to characterize the complexes with net charges +1 and +2. The spectrum of the +1 complex can be explained in terms of a configuration predominantly stabilized by a robust bidentate coordination of guanidinium with a carboxylate group formed from the deprotonation of one side group of the crown ether. The released proton is transferred to the amino terminus of arginine, which then coordinates with the crown ether ring. In an alternative type of conformation, partly consistent with experiment, the amino terminus is neutral and the guanidinium group inserts into the crown ether cavity. In the +2 complexes, arginine is always doubly protonated and the most stable conformations are characterized by a tripodal coordination of the ammonium -NH group of arginine with the oxygen atoms of the macrocycle ring, while the interactions of the amino acid with the side carboxylic acid groups of the crown ether acquire a remarkable lesser role.
Tipo de publicação: JOURNAL ARTICLE
Nome de substância:0 (Ammonium Compounds); 0 (Crown Ethers); 0 (Protons); 63J177NC5B (18-crown-6); 94ZLA3W45F (Arginine); JU58VJ6Y3B (Guanidine)


  6 / 1523 MEDLINE  
              first record previous record next record last record
seleciona
para imprimir
Fotocópia
Texto completo
PMID:29342167
Autor:Piotrowska A; Syguda A; Wyrwas B; Chrzanowski L; Luckenbach T; Heipieper HJ
Endereço:Department of Environmental Biotechnology, Helmholtz Centre for Environmental Research-UFZ, Leipzig, Germany.
Título:Effects of ammonium-based ionic liquids and 2,4-dichlorophenol on the phospholipid fatty acid composition of zebrafish embryos.
Fonte:PLoS One; 13(1):e0190779, 2018.
ISSN:1932-6203
País de publicação:United States
Idioma:eng
Resumo:Ionic liquids consisting of a combination of herbicidal anions with a quaternary ammonium cation act as efficient herbicides, which are under consideration to be used in the agriculture. In the present study, we used embryos of the zebrafish (Danio rerio) as a model to assess the toxic potential of ammonium-based ionic liquids for aquatic organisms. As we assumed interference of the partially hydrophobic ionic liquid cation with lipids, we investigated the adaptation response in the lipid composition of the zebrafish embryos, triggered by the ionic compound. Therefore, the impact of ammonium-based ionic liquids with different lengths of the alkyl chain ([C6,C6,C1,C1N][Br], [C8,C8,C1,C1N][Br]) on the phospholipid fatty acid (PLFA) profile of zebrafish embryos up to 72 hours post fertilization (hpf) was examined. Furthermore, the changes in the unsaturation index (UI) of PLFAs, as the sum parameter of membrane fluidity in eukaryotic cells, were presented. The PLFA's UI in the zebrafish embryos upon exposure to quaternary ammonium salts was compared to the UI of the embryos upon exposure to nonionic 2,4-dichlorophenol, which has a similar hydrophobicity but is structurally different to [C8,C8,C1,C1N][Br]. It was shown that for ammonium-based ionic liquid precursors non-specific mode of action occurs and the toxic effect on lipid composition of zebrafish embryos can be well predicted based on chemical properties, like hydrophobicity. Furthermore, the changes in PLFAs, expressed by the UI, can be useful to study toxic effects of organic contamination. However, for zebrafish embryos, after ionic liquids and 2,4-DCP exposure, the changes were observed at high lethal concentrations, which caused the incidence of lethality of 30 and 50% of a group of test animals.
Tipo de publicação: JOURNAL ARTICLE; RESEARCH SUPPORT, NON-U.S. GOV'T
Nome de substância:0 (Ammonium Compounds); 0 (Chlorophenols); 0 (Herbicides); 0 (Ionic Liquids); R669TG1950 (2,4-dichlorophenol)


  7 / 1523 MEDLINE  
              first record previous record next record last record
seleciona
para imprimir
Fotocópia
Texto completo
PMID:29406102
Autor:Huang J; Kankanamge NR; Chow C; Welsh DT; Li T; Teasdale PR
Endereço:Natural and Built Environments Research Centre, School of Natural and Built Environments, University of South Australia, SA 5095, Australia; Future Industries Institute, University of South Australia, SA 5095, Australia; Environmental Futures Research Institute, School of Environment, Griffith Unive
Título:Removing ammonium from water and wastewater using cost-effective adsorbents: A review.
Fonte:J Environ Sci (China); 63:174-197, 2018 Jan.
ISSN:1001-0742
País de publicação:Netherlands
Idioma:eng
Resumo:Ammonium is an important nutrient in primary production; however, high ammonium loads can cause eutrophication of natural waterways, contributing to undesirable changes in water quality and ecosystem structure. While ammonium pollution comes from diffuse agricultural sources, making control difficult, industrial or municipal point sources such as wastewater treatment plants also contribute significantly to overall ammonium pollution. These latter sources can be targeted more readily to control ammonium release into water systems. To assist policy makers and researchers in understanding the diversity of treatment options and the best option for their circumstance, this paper produces a comprehensive review of existing treatment options for ammonium removal with a particular focus on those technologies which offer the highest rates of removal and cost-effectiveness. Ion exchange and adsorption material methods are simple to apply, cost-effective, environmentally friendly technologies which are quite efficient at removing ammonium from treated water. The review presents a list of adsorbents from the literature, their adsorption capacities and other parameters needed for ammonium removal. Further, the preparation of adsorbents with high ammonium removal capacities and new adsorbents is discussed in the context of their relative cost, removal efficiencies, and limitations. Efficient, cost-effective, and environmental friendly adsorbents for the removal of ammonium on a large scale for commercial or water treatment plants are provided. In addition, future perspectives on removing ammonium using adsorbents are presented.
Tipo de publicação: JOURNAL ARTICLE; REVIEW
Nome de substância:0 (Ammonium Compounds); 0 (Waste Water); 0 (Water Pollutants, Chemical)


  8 / 1523 MEDLINE  
              first record previous record next record last record
seleciona
para imprimir
Fotocópia
Texto completo
PMID:29355318
Autor:Han G; Chen L; Wang Q; Wu M; Liu Y; Wang Q
Endereço:State Key Laboratory of Elemento-Organic Chemistry, Research Institute of Elemento-Organic Chemistry, College of Chemistry, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Nankai University , Tianjin 300071, China.
Título:Design, Synthesis, and Antitobacco Mosaic Virus Activity of Water-Soluble Chiral Quaternary Ammonium Salts of Phenanthroindolizidines Alkaloids.
Fonte:J Agric Food Chem; 66(4):780-788, 2018 Jan 31.
ISSN:1520-5118
País de publicação:United States
Idioma:eng
Resumo:To study the influence of the substituent at the N-10 position on antiviral activity, the chiral quaternary ammonium salt derivatives of R- and S-tylophorine were designed, synthesized, and evaluated for antiviral activity against tobacco mosaic virus (TMV). The bioassay results indicated that most of the designed structural analogues showed good in vivo anti-TMV activity, among which propargyl quaternary ammonium salt compound S-7b showed the best anti-TMV activities (80.5%, 77.6%, 76.6%, 82.1%) at 500 µg/mL both in vitro and in vivo in the laboratory. In the field trials of antiviral efficacy against TMV, S-7b as well exhibited better activities than control plant virus inhibitors. The stability of compound S-7b was obviously increased, and its solubility was more than 500-times higher than that of S-tylophorine. Therefore, chiral quaternary ammonium salt S-7b was expected to be developed as a promising candidate as an inhibitor of plant virus.
Tipo de publicação: JOURNAL ARTICLE
Nome de substância:0 (Alkaloids); 0 (Ammonium Compounds); 0 (Antiviral Agents); 0 (Indolizines); 0 (Phenanthrenes); 059QF0KO0R (Water); O41630Y8V3 (tylophorine)


  9 / 1523 MEDLINE  
              first record previous record next record last record
seleciona
para imprimir
Fotocópia
Texto completo
PMID:28450258
Autor:Han Y; Sun Y; Chen H; Guo X; Yu C; Li Y; Liu J; Xiao B
Endereço:Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China.
Título:Effects of wastewater treatment processes on the sludge reduction system with 2,4-dichlorophenol: Sequencing batch reactor and anaerobic-anoxic-oxic process.
Fonte:J Biotechnol; 251:99-105, 2017 Jun 10.
ISSN:1873-4863
País de publicação:Netherlands
Idioma:eng
Resumo:The effects of two wastewater treatment processes (sequencing batch reactor, SBR; and anaerobic-anoxic-oxic, A2O) on sludge reduction with metabolic uncoupler 2,4-dichlorophenol (DCP) were studied in laboratory. The experimental results showed that the reduction of cumulative excess sludge in SBR and A2O was 43.7% and 44.2%, respectively, during the stable stage of the test. The two processes had similar average sludge yield and sludge yield reduction, i.e., 0.306 and 0.305mg of SS/mg chemical oxygen demand (COD), and 16.9% and 17.8%, respectively. The effect of DCP on the wastewater treatment efficiencies (namely, removal of COD, total nitrogen, NH -N, and total phosphorus) of the two processes were also similar. SBR was more likely to slightly retard the increase of activated sludge SVI with lesser increase in extracellular polymeric substances and protein/polysaccharide ratio. Although DCP did not dramatically affect the microbial communities of sludge, SBR was more favorable for increasing the activated sludge SOUR and maintaining the primary microorganisms of sludge than A2O.
Tipo de publicação: JOURNAL ARTICLE
Nome de substância:0 (Ammonium Compounds); 0 (Chlorophenols); 0 (Sewage); 0 (Water Pollutants, Chemical); 27YLU75U4W (Phosphorus); N762921K75 (Nitrogen); R669TG1950 (2,4-dichlorophenol); S88TT14065 (Oxygen)


  10 / 1523 MEDLINE  
              first record previous record
seleciona
para imprimir
Fotocópia
Texto completo
PMID:29101854
Autor:Gong L; Zhang S; Chen D; Liu K; Lu J
Endereço:Ministry of Education Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, College of Environment, Hohai University, Nanjing, 210098, China.
Título:Response of biofilms-leaves of two submerged macrophytes to high ammonium.
Fonte:Chemosphere; 192:152-160, 2018 Feb.
ISSN:1879-1298
País de publicação:England
Idioma:eng
Resumo:Submerged macrophytes can provide attached surface for biofilms (known as periphyton) growth. In the present study, the alterations in biofilms formation, and chemical compositions and physiological responses were investigated on leaves of Vallisneria asiatica and Hydrilla verticillata exposed to 0.1 mg L (control) or with 10 mg L NH -N for 13 days. Results from physiological and biochemical indices (content of H O , malondialdehyde, total chlorophyll and activity of superoxide dismutase, catalase and peroxidase) showed that high ammonium caused oxidative damage to leaves of two species of plant. Multifractal analysis (based on scanning electron microscope images) showed that for the same plant, the values of width â–³α (â–³α = α -α ) of the f(α) and Δf (Δf = f(α )-f(α )) were smaller on leaves surface of two species of plant treated with 10 mg L NH -N for 13 days than their controls, suggesting high ammonium treatments reduced morphological heterogeneity of leaf surface and enhanced area of the colony-like biofilms. X-ray photoelectron spectroscopy analysis showed that C, O, N and P were dominant elements on leaves surface of two species of plant and ammonium application increased the percentage of C but decreased that of O. High ammonium increased C1 (C-C or C-H) percentage but decreased C2 (C-O) and C3 (O-C-O or C=O) percentage on leaves surface of two species of plant, indicating that ammonium stress changed the surface chemical states and thus might reduce the capacity of leaves to adsorb nutrients from water column. Our results provided useful information to understand ammonium induced toxicity to submerged macrophytes.
Tipo de publicação: JOURNAL ARTICLE
Nome de substância:0 (Ammonium Compounds); 0 (Plant Proteins); 1406-65-1 (Chlorophyll); 4Y8F71G49Q (Malondialdehyde); EC 1.11.1.- (Peroxidases); EC 1.11.1.6 (Catalase); EC 1.15.1.1 (Superoxide Dismutase)



página 1 de 153 ir para página                         
   


Refinar a pesquisa
  Base de dados : MEDLINE Formulário avançado   

    Pesquisar no campo  
1  
2
3
 
           



Search engine: iAH v2.6 powered by WWWISIS

BIREME/OPAS/OMS - Centro Latino-Americano e do Caribe de Informação em Ciências da Saúde