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1.
Undersea Hyperb Med ; 46(4): 503-507, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31509906

RESUMO

We hypothesized that heart rate variability (HRV) can be used as a physiological monitor of exposures to hypercapnia. HRV was analyzed in 15 male subjects breathing air and then air plus 4%, 5% or 6% carbon dioxide (CO2). A progressive elevation in randomness of HRV best depicted as a divergence of data on Poincar é plots of self-similarity occurred as CO2 increased, and resolved when returning sd to ambient conditions. Results indicate that HRV may be useful as a prompt (⟨ 2 minute) early warning of hypercapnia that occurs prior to overt symptomatology.


Assuntos
Frequência Cardíaca , Hipercapnia/diagnóstico , Administração por Inalação , Adulto , Ar , Dióxido de Carbono/administração & dosagem , Estudos Cross-Over , Eletrocardiografia , Humanos , Hipercapnia/fisiopatologia , Masculino , Pessoa de Meia-Idade , Nitrogênio/administração & dosagem , Oxigênio/administração & dosagem , Sintomas Prodrômicos , Adulto Jovem
2.
Sci Total Environ ; 686: 1129-1139, 2019 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-31412509

RESUMO

Global change apart from ecosystem processes also influences the community structure of key organisms, such as arbuscular mycorrhizal fungi (AMF). We conducted a 3-year experiment where we suppressed with benomyl mycorrhiza to understand how AMF alter the plant community structure under warming and nitrogen (N) addition. The elemental content and foliar tissue stoichiometry of the dominant species Leymus chinensis and the subordinate species Puccinellia tenuiflora were studied along with soil nutrient stoichiometries. Overall, N addition enhanced plant N: phosphorus (P) ratios at a greater level than experimental warming did. Under global change conditions, AMF symbionts significantly increased soil available P concentrations, promoted plant P absorption and decreased the plant N:P ratios. AMF alleviate P limitation by reducing plant N:P ratios. Our results highlight that the negative influence of global change on plant productivity might cancel each other out through the additive effects of AMF and that global change will increase the dependency of plants on their mycorrhizal symbionts.


Assuntos
Aquecimento Global , Micorrizas/fisiologia , Nitrogênio/fisiologia , Fósforo/fisiologia , Poaceae/microbiologia , China , Fertilizantes/análise , Temperatura Alta , Nitrogênio/administração & dosagem
3.
Arq. bras. med. vet. zootec. (Online) ; 71(4): 1395-1402, jul.-ago. 2019. tab, graf
Artigo em Inglês | LILACS, VETINDEX | ID: biblio-1038629

RESUMO

The effect of four nitrogen levels (0, 40, 80 and 120kg N ha-1), applied before deferment on the beef cattle production and structural variables on Urochloa decumbens (signal grass) were assessed from January to October 2012 and from January to September 2013. A randomized block design with three replicates was adopted, in an arrangement of repeated measures in time (grazing period). An interaction effect between nitrogen level and grazing period was observed on extended-plant height and herbage mass. As the nitrogen levels were increased, extended-plant height, herbage mass, total herbage allowance, and efficiency of conversion of fertilizer into herbage were increased. Throughout the grazing period, pasture height, extended-plant height, percentage of leaves, herbage and morphological components allowance, and percentages of leaves and stems in the herbage apparently selected by the animal decreased. Nitrogen levels had no effect on average daily gain or gain per area in the first year. A fixed deferment period with increasing levels of nitrogen fertilization on signal grass pastures does not influence the average daily gain per animal, reduces the efficiency of the nitrogen fertilizer and negatively changes the structural characteristics of the pasture.(AU)


Foi avaliado o efeito de quatro doses de nitrogênio (0, 40, 80 e 120kg N ha -1 ), aplicadas antes do diferimento, sobre o desempenho de bovinos e as características estruturais de Urochloa decumbens (capim-braquiária), de janeiro a outubro de 2012 e de janeiro a setembro de 2013. Um delineamento de blocos ao acaso foi utilizado em arranjo de medidas repetidas no tempo (período de pastejo). Foi observada interação entre doses de nitrogênio e período de pastejo na altura da planta estendida e na massa de forragem. As doses de nitrogênio incrementaram a altura da planta estendida, a massa de forragem, a oferta de forragem e a eficiência de conversão do nitrogênio em forragem. No decorrer do período de pastejo, a altura do pasto, a altura da planta estendida, a porcentagem de lâminas foliares, a oferta de forragem e dos seus componentes morfológicos e a porcentagem de lâminas e colmos da forragem aparentemente selecionada pelos animais diminuíram. As doses de nitrogênio não exerceram efeito sobre o ganho diário e o ganho diário por área no primeiro ano. O período de diferimento fixo com aumento das doses de nitrogênio em pastos de capim-braquiária não influencia o ganho diário por animal, reduz a eficiência da adubação nitrogenada e afeta negativamente a estrutura do pasto.(AU)


Assuntos
Animais , Bovinos , Brachiaria/crescimento & desenvolvimento , Fenômenos Fisiológicos da Nutrição Animal , Nitrogênio/administração & dosagem , Pastagens/métodos , Fertilizantes
4.
PLoS One ; 14(7): e0219161, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31339879

RESUMO

Ammonium pulse attributed to runoff of urban surface and agriculture following heavy rain is common in inland aquatic systems and can cause profoundly effects on the growth of macrophytes, especially when combined with low light. In this study, three patterns of NH4-N pulse (differing in magnitude and frequency) were applied to examine their effects on the growth of three submersed macrophytes, namely, Myriophyllum spicatum, Potamogeton maackianus, and Vallisneria natans, in terms of biomass, height, branch/ramet number, root length, leaf number, and total branch length under high and low light. Results showed that NH4-N pulse caused negative effects on the biomass of the submerged macrphytes even on the 13th day after releasing NH4-N pulse. The negative effects on M. spicatum were significantly greater than that on V. natans and P. maackianus. The effects of NH4-N pulse on specific species depended on the ammonium loading patterns. The negative effects of NH4-N pulse on P. maackianus were the strongest at high loading with low frequency, and on V. natans at moderate loading with moderate frequency. For M. spicatum, no significant differences were found among the three NH4-N pulse patterns. Low light availability did not significantly aggregate the negative effects of NH4-N pulse on the growth of the submersed macrophytes. Our study contributes to revealing the roles of NH4-N pulse on the growth of aquatic plants and its species specific effects on the dynamics of submerged macrophytes in lakes.


Assuntos
Compostos de Amônio/administração & dosagem , Hydrocharitaceae/efeitos dos fármacos , Hydrocharitaceae/crescimento & desenvolvimento , Lagos/análise , Potamogetonaceae/efeitos dos fármacos , Potamogetonaceae/crescimento & desenvolvimento , Saxifragales/efeitos dos fármacos , Saxifragales/crescimento & desenvolvimento , Compostos de Amônio/toxicidade , Organismos Aquáticos/efeitos dos fármacos , Organismos Aquáticos/crescimento & desenvolvimento , Biomassa , China , Ecossistema , Eutrofização/efeitos dos fármacos , Nitrogênio/administração & dosagem , Nitrogênio/toxicidade , Chuva/química , Água/análise , Poluentes Químicos da Água/administração & dosagem , Poluentes Químicos da Água/toxicidade
5.
Biosci Biotechnol Biochem ; 83(10): 1924-1936, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31244380

RESUMO

This study examined the physiological effects of different amounts of nitrogen (N) supplementation (0 to 2.72 kg/year) on the citrus cultivar Huangguogan (Citrus reticulata × Citrus sinensis). Root activity, chlorophyll content, and fruit quality were measured, and the activities of the antioxidant enzymes superoxide dismutase (SOD), guaiacol peroxidase (POD), and catalase (CAT), and the contents of malondialdehyde (MDA) and soluble protein in root, leaf, and fruit tissues were examined at different developmental stages. Root activity, chlorophyll content, fruit quality, antioxidant enzyme activity, MDA content, and soluble protein content increased in plants treated with an appropriate amount of N. Both excessive N and N deficiency decreased the content of MDA and the activities of antioxidant enzymes. Application of 1.36-1.81 kg N/year is suggested for citrus fertilization and the lower end of this range is recommended for minimizing environmental impact and production cost.


Assuntos
Antioxidantes/metabolismo , Catalase/metabolismo , Citrus/enzimologia , Citrus/crescimento & desenvolvimento , Nitrogênio/administração & dosagem , Peroxidase/metabolismo , Superóxido Dismutase/metabolismo , Clorofila/metabolismo , Citrus/metabolismo , Malondialdeído/metabolismo , Proteínas de Plantas/metabolismo , Estruturas Vegetais/enzimologia , Estruturas Vegetais/metabolismo
6.
Am J Vet Res ; 80(7): 631-636, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31246120

RESUMO

OBJECTIVE: To assess effects of nitrogen and helium on efficacy of an alveolar recruitment maneuver (ARM) for improving pulmonary mechanics and oxygen exchange in anesthetized horses. ANIMALS: 6 healthy adult horses. PROCEDURES: Horses were anesthetized twice in a randomized crossover study. Isoflurane-anesthetized horses in dorsal recumbency were ventilated with 30% oxygen and 70% nitrogen (treatment N) or heliox (30% oxygen and 70% helium; treatment H) as carrier gas. After 60 minutes, an ARM was performed. Optimal positive end-expiratory pressure was identified and maintained for 120 minutes. Throughout the experiment, arterial blood pressures, heart rate, peak inspiratory pressure, dynamic compliance (Cdyn), and Pao2 were measured. Variables were compared with baseline values and between treatments by use of an ANOVA. RESULTS: The ARM resulted in significant increases in Pao2 and Cdyn and decreases in the alveolar-arterial gradient in the partial pressure of oxygen in all horses. After the ARM and during the subsequent 120-minute phase, mean values were significantly lower for treatment N than treatment H for Pao2 and Cdyn. Optimal positive end-expiratory pressure was consistently 15 cm H2O for treatment N, but it was 10 cm H2O (4 horses) and 15 cm H2O (2 horses) for treatment H. CONCLUSIONS AND CLINICAL RELEVANCE: An ARM in anesthetized horses might be more efficacious in improving Pao2 and Cdyn when animals breathe helium instead of nitrogen as the inert gas.


Assuntos
Anestesia Geral/veterinária , Hélio/administração & dosagem , Cavalos/fisiologia , Nitrogênio/administração & dosagem , Oxigênio/administração & dosagem , Alvéolos Pulmonares/fisiologia , Anestesia Geral/métodos , Animais , Estudos Cross-Over , Feminino , Isoflurano/administração & dosagem , Masculino , Posicionamento do Paciente/métodos , Posicionamento do Paciente/veterinária , Distribuição Aleatória
7.
J Agric Food Chem ; 67(27): 7616-7625, 2019 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-31251044

RESUMO

Rapid hydrolysis of urea results in further fertilization frequency and excessive nitrogen (N) input. A modified urea, dimethylolurea (DMU), was synthesized in this study. The structure of the sample was characterized by Fourier transform infrared and nuclear magnetic resonance analysis, manifesting the formation of DMU. N release investigation confirmed that DMU enabling provided a gradual N supply. The N leaching experiment indicated that increasing the applied DMU significantly reduced the NH4+-N, NO3--N, and total N leaching, compared with urea application alone. The application effect on maize and wheat was evaluated. The results revealed that singly applied DMU with 100% or 80% N input, irrespective of the amount, promoted crop yield and agronomic characteristic and N use efficiency (NUE) of maize and wheat, beyond urea with two split applications at the recommended rate. Thus, the potential availability of DMU was proven; this could be widely used in agricultural fields as a slow-release fertilizer.


Assuntos
Produtos Agrícolas/crescimento & desenvolvimento , Fertilizantes , Compostos de Metilureia/administração & dosagem , Nitrogênio/administração & dosagem , Agricultura/métodos , Preparações de Ação Retardada , Fertilizantes/análise , Compostos de Metilureia/síntese química , Compostos de Metilureia/química , Espectroscopia de Infravermelho com Transformada de Fourier , Triticum/crescimento & desenvolvimento , Zea mays/crescimento & desenvolvimento
8.
Diving Hyperb Med ; 49(2): 119-126, 2019 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-31177518

RESUMO

INTRODUCTION: Cognitive impairment related to inert gas narcosis (IGN) is a threat to diving safety and operations at depth that might be reduced by using enriched air nitrox (EANx) mixtures. Using critical flicker fusion frequency (CFFF), a possible early detection of cognitive abilities/cerebral arousal impairment when breathing different oxygen (O2) fractions was investigated. METHODS: Eight male volunteers performed, in random order, two dry chamber dives breathing either air or EANx40 (40% O2-60% nitrogen) for 20 minutes (min) at 0.4 MPa. Cognition and arousal were assessed before the dive; upon arrival at 0.4 MPa; after 15 min exposure at 0.4 MPa; on surfacing and 30 min post-dive using behavioural computer-based testing psychology experiment building language (PEBL) and by CFFF while continuously recording brain oxygenation with near-infrared spectroscopy. RESULTS: In both breathing conditions, CFFF and PEBL demonstrated a significant inverse correlation (Pearson r of -0.90, P < 0.0001), improved cognitive abilities/cerebral arousal occurred upon arrival at 0.4 MPa followed by a progressive deterioration. Initial brain activation was associated with a significant increase in oxyhaemoglobin (HbO2) and a simultaneous decrease of deoxyhaemoglobin (HHb). The magnitude of the changes was significantly greater under EANx (P = 0.038). CONCLUSIONS: Since changes were not related to haemodynamic variables, HbO2 and HHb values indicate a significant, O2-dependent activation in the prefrontal cortex. Owing to the correlation with some tests from the PEBL, CFFF could be a convenient measure of cognitive performance/ability in extreme environments, likely under the direct influence of oxygen partial pressure, a potent modulator of IGN symptoms.


Assuntos
Disfunção Cognitiva , Mergulho , Nitrogênio/efeitos adversos , Oxigênio/efeitos adversos , Disfunção Cognitiva/induzido quimicamente , Mergulho/efeitos adversos , Fusão Flicker , Humanos , Nitrogênio/administração & dosagem , Oxigênio/administração & dosagem
9.
J Anim Physiol Anim Nutr (Berl) ; 103(4): 1168-1173, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31062424

RESUMO

Experiments were conducted to estimate daily N maintenance requirements (NMRs) and the genetic potential for daily N retention (NRmax T) of pullets in growth phase. Three nitrogen balance trials were conducted, and a total of 48 Hy-line W-36 pullets were used in each trial in age periods (starter: 14-28, grower: 56-70 and developer: 98-112 days). The treatments consisted of six graded levels of nitrogen in the diets (L1 = 8, L2 = 16, L3 = 24, L4 = 32, L5 = 40 and L6 = 48 g N/kg of feed), formulated using the dilution technique. The regression analyses between nitrogen intake and nitrogen excretion were performed to fit the exponential function and to determine the NMR. The daily NMRs that were estimated at 294, 331 and 355 mg/BWkg 0.67 for the initial, grower and developer periods, respectively, were applied for further calculation of NRmax T as the threshold value of the function between N intake and daily N balance. The NRmax T was estimated by a statistical procedure following several iteration steps by the Levenberg-Marquardt algorithm until the sum of the squares of the residual was minimized. The NRmax T was estimated at 3,200, 2,633 and 1,826 mg/BWkg 0.67 for starter, grower and developer periods respectively. The determined model parameters were the precondition for modelling of the amino acid requirement based on an exponential N-utilization model and depended on performance and dietary amino acid efficiency. This procedure will be further developed and applied in the subsequent study.


Assuntos
Ração Animal/análise , Galinhas/crescimento & desenvolvimento , Dieta/veterinária , Nitrogênio/administração & dosagem , Nitrogênio/metabolismo , Fenômenos Fisiológicos da Nutrição Animal , Animais , Galinhas/metabolismo , Feminino , Necessidades Nutricionais
10.
Appl Biochem Biotechnol ; 189(1): 217-232, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-30972705

RESUMO

This study firstly introduced a silicone rubber membrane (SRM) into microbial fuel cell (MFC) for passive oxygen supply to simultaneously remove phenol and nitrogen from synthetic coke-oven wastewater diluted with seawater. Passive oxygen transport with biofilm on the membrane was improved by ~ 18-fold in comparison with the one without a biofilm. In addition, although the oxygen supply was passive, nitrification accounted for 34% of those aeration conditions. It was also found that silicone rubber membrane can control NO2--N and/or NO3--N production. A dual-chamber MFC treating the synthetic coke-oven wastewater achieved a maximum power density of 54 mW m-2 with a coulombic efficiency of 2.7%. We conclude that silicone rubber membrane is effective for sustainable coke-oven wastewater treatment in MFCs.


Assuntos
Fontes de Energia Bioelétrica , Carbono/administração & dosagem , Membranas Artificiais , Nitrogênio/administração & dosagem , Oxigênio/administração & dosagem , Elastômeros de Silicone/química
11.
Nat Commun ; 10(1): 1374, 2019 03 26.
Artigo em Inglês | MEDLINE | ID: mdl-30914651

RESUMO

Changes in nutrient dose have dramatic effects on gene expression and development. One outstanding question is whether organisms respond to changes in absolute nutrient amount (moles) vs. its concentration in water (molarity). This question is particularly relevant to plants, as soil drying can alter nutrient concentration, without changing its absolute amount. To compare the effects of amount vs. concentration, we expose rice to a factorial matrix varying the dose of nitrogen (N) and water (W) over a range of combinations, and quantify transcriptome and phenotype responses. Using linear models, we identify distinct dose responses to either N-moles, W-volume, N-molarity (N/W), or their synergistic interaction (N×W). Importantly, genes whose expression patterns are best explained by N-dose and W interactions (N/W or N×W) in seedlings are associated with crop outcomes in replicated field trials. Such N-by-W responsive genes may assist future efforts to develop crops resilient to increasingly arid, low nutrient soils.


Assuntos
Produção Agrícola , Produtos Agrícolas/genética , Regulação da Expressão Gênica de Plantas/genética , Nitrogênio/administração & dosagem , Nutrientes/administração & dosagem , Oryza/genética , Água/administração & dosagem , Perfilação da Expressão Gênica , Genoma de Planta , Modelos Lineares , Fenótipo , Plântula/genética , Solo
12.
PLoS One ; 14(1): e0210818, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30703117

RESUMO

Carbon dioxide (CO2) is one of the most commonly used gas euthanasia agents in mice, despite reports of aversion and nociception. Inert gases such as nitrogen (N2) may be a viable alternative to carbon dioxide. Here we compared behavioural and electrophysiological reactions to CO2 or N2 at either slow fill or rapid fill in C57Bl/6 mice undergoing gas euthanasia. We found that mice euthanised with CO2 increased locomotor activity compared to baseline, whereas mice exposed to N2 decreased locomotion. Furthermore, mice exposed to CO2 showed significantly more vertical jumps and freezing episodes than mice exposed to N2. We further found that CO2 exposure resulted in increased theta:delta of the EEG, a measure of excitation, whereas the N2 decreased theta:delta. Differences in responses were not oxygen-concentration dependent. Taken together, these results demonstrate that CO2 increases both behavioural and electrophysiological excitation as well as producing a fear response, whereas N2 reduces behavioural activity and central neurological depression and may be less aversive although still produces a fear response. Further studies are required to evaluate N2 as a suitable euthanasia agent for mice.


Assuntos
Dióxido de Carbono/administração & dosagem , Eutanásia Animal/métodos , Nitrogênio/administração & dosagem , Bem-Estar do Animal , Animais , Comportamento Animal/efeitos dos fármacos , Comportamento Animal/fisiologia , Dióxido de Carbono/efeitos adversos , Eletroencefalografia/efeitos dos fármacos , Fenômenos Eletrofisiológicos , Medo/efeitos dos fármacos , Medo/fisiologia , Feminino , Gases/administração & dosagem , Gases/efeitos adversos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Atividade Motora/efeitos dos fármacos , Atividade Motora/fisiologia , Nitrogênio/efeitos adversos , Gases Nobres/administração & dosagem , Gases Nobres/efeitos adversos
14.
Sci Total Environ ; 660: 69-79, 2019 Apr 10.
Artigo em Inglês | MEDLINE | ID: mdl-30639720

RESUMO

Soil amendment with biochar has received increased attention because of its potential to i) sequester carbon and ii) reduce N2O emission when applied to N fertilised soils. To study the effect of biochar origin on greenhouse gas emission in two contrasting soil types, we used a robotized continuous flow incubation system and δ13C stable isotope approach to compare four biochar types (feed stock: olive mill, corn cob, pistachio shell, cotton stalk) in an alkaline clay soil and two selected biochar types (feed stock: olive mill and corn cob) in an acidic sandy soil. Furthermore, high-throughput sequencing of 16S rRNA genes was performed at the end of the incubation to investigate the effect of different biochars on bacterial community structure in the two different soils. In the alkaline clay soil, all biochar types in conjunction with N fertiliser decreased CO2 emissions up to 12% compared to the N added control treatment causing negative priming, whereas no significant effect of biochar addition on N2O emissions was observed. In contrast, application of olive mill biochar to the acidic sandy soil significantly increased soil pH, CO2, and N2O fluxes, whereas no significant effect of corn cob biochar addition was observed. There was a significant linear relationship between the biochar induced increase in soil pH and the biochar induced increase in soil born N2O emission. Additionally, we detected a clear variation in bacterial community structure in the acidic sandy soil (phyla Acidobacteria, Nitrospirare, and Arthrobacter) with the olive mill biochar addition. Overall, the amendment of different biochars failed to mitigate N2O emissions in both soil types when mineral fertiliser was added. Furthermore, amendment of olive mill biochar stimulated both N2O and CO2 emissions in the low pH sandy soil and altered the bacterial community structure, which was possibly related to its liming effect.


Assuntos
Poluentes Atmosféricos/análise , Bactérias , Carvão Vegetal/análise , Monitoramento Ambiental , Gases de Efeito Estufa/análise , Microbiota , Solo/química , Bactérias/classificação , Fertilizantes/análise , Alemanha , Nitrogênio/administração & dosagem , Turquia
15.
Ann Phys Rehabil Med ; 62(1): 43-48, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30099150

RESUMO

BACKGROUND: There is little evidence regarding the best way to treat adhesive capsulitis. Physical therapy can reduce pain and improve function and range of motion. However, we lack clear indications on the regimen, techniques or intensity of physical therapy to achieve better results. Intensive physical therapy seems to be confined to the later stages of adhesive capsulitis (chronic stage) given that rehabilitation-induced pain could worsen the outcomes. Here we describe a protocol for a study comparing the efficacy of a standardized program of intensive mobilization under analgesic gas to a similar program under placebo gas and questioning the impact of pain. METHOD/DESIGN: A randomized, double-blind, multicenter study - the MEOPA Trial - was designed to include adults with strictly defined clinical adhesive capsulitis for a 14-day intensive physical rehabilitation program under an equimolar mixture of oxygen and nitrous oxide or sham gas administration. Efficacy will be assessed by the Constant-Murley score. Data for secondary criteria including pain, disability, quality of life and perceived efficacy by the patient or physiotherapist will be collected over 6 months. DISCUSSION: This randomized controlled trial has been designed to test the effectiveness of intensive physical therapy under a simple and safe analgesic method. This study will also address the effect of pain during rehabilitation in adhesive capsulitis. Furthermore, results from the 6-month multidimensional follow-up of painful mobilization for this condition could be extrapolated to other musculoskeletal conditions. TRIAL REGISTRATION: ClinicalTrials.gov No. NCT01087229.


Assuntos
Analgesia/métodos , Analgésicos/administração & dosagem , Bursite/reabilitação , Nitrogênio/administração & dosagem , Oxigênio/administração & dosagem , Modalidades de Fisioterapia , Adulto , Bursite/fisiopatologia , Método Duplo-Cego , Feminino , Humanos , Masculino , Medição da Dor , Qualidade de Vida , Ensaios Clínicos Controlados Aleatórios como Assunto , Amplitude de Movimento Articular , Resultado do Tratamento
16.
Pest Manag Sci ; 75(4): 1150-1158, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30324681

RESUMO

BACKGROUND: Field experiments were carried out in 2016 and 2017 to study the influence of timing the application of nitrogen fertilizer (N-fertilizer) on the susceptibility of potatoes to early blight. We hypothesized that potatoes that receive N-fertilizer as split applications or a one-time application at emergence will have a higher N content and be less susceptible to early blight than those that receive N-fertilizer as a one-time application before planting. N-fertilizer was applied either as a one-time application before planting or at emergence and as split applications. RESULTS: Potatoes that did not receive N-fertilizer were more susceptible to early blight [high area under the disease progress curve (AUDPC)] than those that did receive N-fertilizer (low AUDPC). The timing of N-fertilizer application had a significant effect on the susceptibility of potatoes to early blight. Potatoes that received the entire quantity of N-fertilizer at emergence or as split applications had higher N contents and were less susceptible to early blight than those that received the entire quantity of N-fertilizer before planting. Potatoes that did not receive N-fertilizer had a markedly lower starch yield than potatoes that received N-fertilizer. Potatoes that received the entire quantity of N-fertilizer before planting had a lower starch yield than potatoes that received the entire quantity of N-fertilizer at emergence or as split applications. CONCLUSION: N-fertilizer applied as a one-time application at emergence or as a split application was the best treatment to ensure both high N content and lower attack of early blight, which confirms our hypothesis. © 2018 Society of Chemical Industry.


Assuntos
Alternaria/fisiologia , Produção Agrícola/métodos , Fertilizantes/análise , Nitrogênio/administração & dosagem , Doenças das Plantas/microbiologia , Solanum tuberosum/efeitos dos fármacos , Dinamarca , Solanum tuberosum/microbiologia
17.
Sci Total Environ ; 650(Pt 2): 1787-1794, 2019 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-30278423

RESUMO

Little is known about the effects of nitrogen (N) fertilization rates on ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) and their differential contribution to nitrous oxide (N2O) production, particularly in greenhouse based high N input vegetable soils. Six N treatments (N1, N2, N3, N4, N5 and N6 representing 0, 293, 587, 880, 1173 and 1760 kg N ha-1 yr-1, respectively) were continuously managed for three years in a typically intensified vegetable field in China. The aerobic incubation experiment involving these field-treated soils was designed to evaluate the relative contributions of AOA and AOB to N2O production by using acetylene or 1-octyne as inhibitors. The results showed that the soil pH and net nitrification rate gradually declined with increasing the fertilizer N application rates. The AOA were responsible for 44-71% of the N2O production with negligible N2O from AOB in urea unamended control soils. With urea amendment, the AOA were responsible for 48-53% of the N2O production in the excessively fertilized soils, namely the N5-N6 soils, while the AOB were responsible for 42-55% in the conventionally fertilized soils, namely the N1-N4 soils. Results indicated that overdose fertilization induced higher AOA-dependent N2O production than AOB, whereas urea supply led to higher AOB-dependent N2O production than AOA in conventionally fertilized soils. Additionally, a positive relationship existed between N2O production and NO2- accumulation during the incubation. Further mechanisms for NO2--dependent N2O production in intensive vegetable soils therefore deserve urgent attention.


Assuntos
Amônia/metabolismo , Archaea/metabolismo , Fertilizantes , Nitrogênio/administração & dosagem , Óxido Nitroso/metabolismo , Microbiologia do Solo , China , Relação Dose-Resposta a Droga , Oxirredução , Estações do Ano , Verduras/crescimento & desenvolvimento
18.
Sci Total Environ ; 654: 863-871, 2019 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-30448675

RESUMO

Global nitrogen (N) enrichment likely alters plant community composition and increases productivity, consequently affecting ecosystem stability. Meanwhile, the effects of N addition on plant community composition and productivity are often influenced by phosphorus (P) nutrition, as the effects of N and P addition and interactions between N and P on plant community structure and productivity are still not well understood. An in situ experiment with N and P addition was conducted in a temperate meadow in northeastern China from 2013 to 2016. The responses of plant community composition, structure, functional group cover, richness and productivity to N and P additions were examined. N addition significantly reduced species richness and diversity but increased aboveground net primary productivity (ANPP) during the four-study-year period. P addition exerted no significant impact on species richness, diversity or ANPP but reduced cover of grasses and increased legume cover. Under N plus P addition, P addition alleviated the negative effects of N addition on community structure by increasing species richness and covers of legume and forbs. N and P additions significantly altered plant community structure and productivity in the functional groups. N addition significantly increased the cover of gramineous and reduced the cover of legume, P addition significantly increased legume cover. Our observations revealed that soil nutrient availability regulates plant community structure and ANPP in response to nutrient enrichment caused by anthropogenic activities in the temperate meadow. Our results highlight that the negative influence of N deposition on plant community composition might be alleviated by P input in the future.


Assuntos
Biomassa , Biota/efeitos dos fármacos , Pradaria , Nitrogênio/metabolismo , Fósforo/metabolismo , China , Nitrogênio/administração & dosagem , Fósforo/administração & dosagem
19.
BMC Plant Biol ; 18(1): 353, 2018 Dec 13.
Artigo em Inglês | MEDLINE | ID: mdl-30545290

RESUMO

BACKGROUND: Nitrogen is one basic element of amino acids and grain protein in wheat. In field experiments, wheat plants were subjected to different timing of nitrogen topdressing treatments: at the stages of emergence of the top fifth leaf (TL5), top third leaf (TL3) and top first leaf (TL1) to test the regulatory effects of nitrogen topdressing timing on grain protein quality. The underlying mechanisms were elucidated by clarifying the relationship between proteolysis in vegetative organs and accumulation of amino acids in the endosperm cavity, conversion of amino acids, and storage protein synthesis in endosperm of wheat grain. RESULTS: Delayed nitrogen topdressing up-regulated gene expression related to nitrogen metabolism and protease synthesis in the flag leaf, followed by more free amino acids being transported to both the cavity and the endosperm from 7 days after anthesis (DAA) to 13 DAA in TL1. TL1 enhanced the conversion between free amino acids in endosperm and upregulated the expression of genes encoding high molecular weight (HMW) and low molecular weight (LMW) subunits and protein disulfide isomerases-like (PDIL) proteins, indicating that the synthesis and folding of glutenin were enhanched by delayed nitrogen topdressing. As a consequense, the content of glutenin macropolymers (GMP) and glutenin increased with delaying nitrogen topdressing. CONCLUSIONS: The results highlight the relationship between nitrogen remobilization and final grain protein production and suggest that the nitrogen remobilization processes could be a potential target for improving the quality of wheat grain. Additionally, specific gene expression related to nitrogen topdressing was identified, which conferred more detailed insights into underlying mechanism on the modification protein quality.


Assuntos
Aminoácidos/metabolismo , Grão Comestível/metabolismo , Nitrogênio/metabolismo , Proteínas de Plantas/metabolismo , Triticum/metabolismo , Aminoácidos/análise , Grão Comestível/química , Endosperma/química , Endosperma/metabolismo , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Nitrogênio/administração & dosagem , Folhas de Planta/metabolismo , Reação em Cadeia da Polimerase em Tempo Real
20.
World J Gastroenterol ; 24(43): 4862-4869, 2018 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-30487696

RESUMO

Endoscopic cryotherapy is a relatively new thermal ablative modality used for the treatment of neoplastic lesions of the esophagus. It relies on cycles of rapid cooling and thawing to induce tissue destruction with a cryogen (liquid nitrogen or carbon dioxide) leading to intra and extra-cellular damage. Surgical treatment was once considered the standard therapeutic intervention for neoplastic diseases of the esophagus and is associated with considerable rates of morbidity and mortality. Several trials that evaluated cryotherapy in Barrett's esophagus (BE) associated neoplasia showed reasonable efficacy rates and safety profile. Cryotherapy has also found applications in the treatment of esophageal cancer, both for curative and palliative intent. Cryotherapy has also shown promising results as salvage therapy in cases refractory to radiofrequency ablation treatment. Cryoballoon focal ablation using liquid nitrogen is a novel mode of cryogen delivery which has been used for the treatment of BE with dysplasia and squamous cell carcinoma. Most common side effects of cryotherapy reported in the literature include mild chest discomfort, esophageal strictures and bleeding. In conclusion, cryotherapy is an effective and safe method for the treatment of esophageal neoplastic processes, ranging from early stages of low grade dysplasia to esophageal cancer.


Assuntos
Esôfago de Barrett/cirurgia , Criocirurgia/métodos , Neoplasias Esofágicas/cirurgia , Esofagoscopia/métodos , Lesões Pré-Cancerosas/cirurgia , Esôfago de Barrett/patologia , Criocirurgia/efeitos adversos , Neoplasias Esofágicas/patologia , Neoplasias Esofágicas/prevenção & controle , Esofagoscopia/efeitos adversos , Esôfago/diagnóstico por imagem , Esôfago/patologia , Humanos , Nitrogênio/administração & dosagem , Cuidados Paliativos/métodos , Complicações Pós-Operatórias/epidemiologia , Complicações Pós-Operatórias/etiologia , Lesões Pré-Cancerosas/patologia , Terapia de Salvação/efeitos adversos , Terapia de Salvação/métodos , Resultado do Tratamento
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