964 resultados para Coffee husk


Relevância:

10.00% 10.00%

Publicador:

Resumo:

Hundreds of plant species have been studied in order to find out the active ingredient responsible for their insecticidal activity against the pests of economic importance. To verify the insecticidal activity in the husk of stem of Croton urucurana Baillon 1864 (Euphorbiaceae) against Anagasta kuehniella Zeller 1879 (Lepidoptera: Pyralidae), the methanolic (EMeOH) extract, dichloromethane fraction (FDM), ethyl acetate fraction (FAE) and crude resin, incorporated into an artificial diet were evaluated. EMeOH (0.5, 1.0 and 2.0%) and crude resin (2.0%) interfered with neither the weight nor the survival of fourth instar larvae and other analyzed parameters. FDM (2.0%) fraction caused mortality of 65%, and the artificial diet containing 2.0, 1.0 and 0.5% FAE caused 100, 55 and 68% mortality respectively when compared with the control, confirming the least efficiency rates of food conversion for FDM(2.0%) and FAE(1.0%). The tryptic analysis performed with the midgut fluid of fourth-instar larvae demonstrated that tryptic and chymiotryptic activities for the larvae fed artificial diet containing EMeOH and crude resin were not different.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

This work describes the preparation and characterization of biogenic modified silica from rice hull ash and its use as a sorbent of cadmium ions. Thus, an agro-industrial residue has been used to produce a new adsorbent product which is able to remove toxic elements. Mesoporous biogenic silica was obtained by alkaline extraction of sodium silicate by hydrolysis with the sol-gel process, and it was modified with salen using 1,2-dichloroethane as a spacer. The surface area of the silica was measured by nitrogen adsorption/desorption analysis. Surface modification was measured by Fourier transform infrared spectroscopy. The degree of functionalization was obtained by elemental analysis. This work showed that biogenic modified silica can be produced in aqueous media from rice hull ash using a simple method, providing an alternative method for adsorbent preparation. Thermogravimetric analysis showed that the salen-modified silica is stable up to 209 C. The modified silica displays appropriate structural characteristics for an adsorbent. The cylindrical pores, open at both ends, allow free diffusion of cadmium ions to the adsorption sites on the silica surface. The surface modification increases cadmium adsorption on the silica surface 100-fold. The salen-modified silica showed specific adsorption for Cd2+ of 44.52 mg/g SiO2 at cadmium concentration of 100 mg/l.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Fluoride (F) is an air pollutant that causes phytotoxicity. Besides the importance of this, losses of agricultural crops in the vicinity of F polluting industries in Brazil have been recently reported. Injuries caused to plant leaf cell structures by excess F are not well characterized. However, this may contribute to understanding the ways in which plant physiological and biochemical processes are altered. A study evaluated the effects of the atmospheric F on leaf characteristics and growth of young trees of sweet orange and coffee exposed to low (0.04 mol L(-1)) or high (0.16 mol L(-1)) doses of HF nebulized in closed chamber for 28 days plus a control treatment not exposed. Gladiolus and ryegrass were used as bioindicators in the experiment to monitor F exposure levels. Fluoride concentration and dry mass of leaves were evaluated. Leaf anatomy was observed under light and electron microscopy. High F concentrations (similar to 180 mg kg(-1)) were found in leaves of plants exposed at the highest dose of HF. Visual symptoms of F toxicity in leaves of citrus and coffee were observed. Analyses of plant tissue provided evidence that F caused degeneration of cell wall and cytoplasm and disorganization of bundle sheath, which were more evident in Gladiolus and coffee. Minor changes were observed for sweet orange and ryegrass. Increase on individual stomatal area was also marked for the Gladiolus and coffee, and which were characterized by occurrence of opened ostioles. The increased F absorption by leaves and changes at the structural and ultrastructural level of leaf tissues correlated with reduced plant growth.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The behaviour of cis isomers of selected mono- and di-acyl chlorogenic acids produced by UV-irradiation has been investigated by LC-MSn. cis Isomers fragment identically to the more common trans isomers. cis-5-Acyl chlorogenic acids are more hydrophobic and elute later than their mono- or di-trans counterparts whereas the reverse is true for cis-3-acyl and cis-4-acyl chlorogenic acids. The cis isomers of 1,3-dicaffeoylquinic acid, the only I-acyl chlorogenic acid investigated, are also more hydrophobic than the di-trans isomer. Coffee leaves had a proportionately greater content of cis isomers relative to trans isomers compared with coffee beans suggesting that UV-irradiation in vivo may also cause geometric isomerisation. (c) 2007 Elsevier Ltd. All rights reserved.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Brevipalpus-transmitted viruses (BTV) cause chlorotic, necrotic and/or ringspot lesions in leaves and stems of orchids, citrus, coffee and several other plant species. There are two different types of BTVs, the nuclear and the cytoplasmic, based on maturation locale in the cell and particle morphology. The orchid fleck virus (OFV) is a BTV that infects orchids. Its short rodlike particles are 32-40 nm in diameter, 100-150 nm in length. OFV is found in the nucleus and is associated with intranuclear electronlucent viroplasms. In 1999, transmission electron microscopy analysis revealed a distinct type of virus causing orchid fleck symptoms. The bacilliform particles, 70-80 nm in diameter and 110-120 nm in length, induced electron-dense viroplasm inclusions in infected cells and resembled the cytoplasmic type associated with BTV, such as the citrus leprosis virus C. Our objective in the present study was to verify whether the cytoplasmic type virus found in orchids could be amplified using primers for other cytoplasmic BTVs, such as CiLV-C and Solanum violaefolium ringspot virus (SvRSV). Additionally, we aimed to differentiate the two BTVs found in orchids: the nuclear and the cytoplasmic types of OFV using microscopy and molecular and serological tools. This virus was not amplified by the CiLV-C and SvRSV primers, and neither the molecular nor the serological tools available to the OFV diagnosis reacted with it, demonstrating that they are definitely different viruses.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Parkinson’s disease (PD) is a progressive, degenerative, neurological disease. The progressive disability associated with PD results in substantial burdens for those with the condition, their families and society in terms of increased health resource use, earnings loss of affected individuals and family caregivers, poorer quality of life, caregiver burden, disrupted family relationships, decreased social and leisure activities, and deteriorating emotional well-being. Currently, no cure is available and the efficacy of available treatments, such as medication and surgical interventions, decreases with longer duration of the disease. Whilst the cause of PD is unknown, genetic and environmental factors are believed to contribute to its aetiology. Descriptive and analytical epidemiological studies have been conducted in a number of countries in an effort to elucidate the cause, or causes, of PD. Rural residency, farming, well water consumption, pesticide exposure, metals and solvents have been implicated as potential risk factors for PD in some previous epidemiological studies. However, there is substantial disagreement between the results of existing studies. Therefore, the role of environmental exposures in the aetiology of PD remains unclear. The main component of this thesis consists of a case-control study that assessed the contribution of environmental exposures to the risk of developing PD. An existing, previously unanalysed, dataset from a local case-control study was analysed to inform the design of the new case-control study. The analysis results suggested that regular exposure to pesticides and head injury were important risk factors for PD. However, due to the substantial limitations of this existing study, further confirmation of these results was desirable with a more robustly designed epidemiological study. A new exposure measurement instrument (a structured interviewer-delivered questionnaire) was developed for the new case-control study to obtain data on demographic, lifestyle, environmental and medical factors. Prior to its use in the case-control study, the questionnaire was assessed for test-retest repeatability in a series of 32 PD cases and 29 healthy sex-, age- and residential suburb-matched electoral roll controls. High repeatability was demonstrated for lifestyle exposures, such as smoking and coffee/tea consumption (kappas 0.70-1.00). The majority of environmental exposures, including use of pesticides, solvents and exposure to metal dusts and fumes, also showed high repeatability (kappas >0.78). A consecutive series of 163 PD case participants was recruited from a neurology clinic in Brisbane. One hundred and fifty-one (151) control participants were randomly selected from the Australian Commonwealth Electoral Roll and individually matched to the PD cases on age (± 2 years), sex and current residential suburb. Participants ranged in age from 40-89 years (mean age 67 years). Exposure data were collected in face-to-face interviews. Odds ratios and 95% confidence intervals were calculated using conditional logistic regression for matched sets in SAS version 9.1. Consistent with previous studies, ever having been a regular smoker or coffee drinker was inversely associated with PD with dose-response relationships evident for packyears smoked and number of cups of coffee drunk per day. Passive smoking from ever having lived with a smoker or worked in a smoky workplace was also inversely related to PD. Ever having been a regular tea drinker was associated with decreased odds of PD. Hobby gardening was inversely associated with PD. However, use of fungicides in the home garden or occupationally was associated with increased odds of PD. Exposure to welding fumes, cleaning solvents, or thinners occupationally was associated with increased odds of PD. Ever having resided in a rural or remote area was inversely associated with PD. Ever having resided on a farm was only associated with moderately increased odds of PD. Whilst the current study’s results suggest that environmental exposures on their own are only modest contributors to overall PD risk, the possibility that interaction with genetic factors may additively or synergistically increase risk should be considered. The results of this research support the theory that PD has a multifactorial aetiology and that environmental exposures are some of a number of factors to contribute to PD risk. There was also evidence of interaction between some factors (eg smoking and welding) to moderate PD risk.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

There is substantial disagreement among published epidemiological studies regarding environmental risk factors for Parkinson’s disease (PD). Differences in the quality of measurement of environmental exposures may contribute to this variation. The current study examined the test–retest repeatability of self-report data on risk factors for PD obtained from a series of 32 PD cases recruited from neurology clinics and 29 healthy sex-, age-and residential suburb-matched controls. Exposure data were collected in face-to-face interviews using a structured questionnaire derived from previous epidemiological studies. High repeatability was demonstrated for ‘lifestyle’ exposures, such as smoking and coffee/tea consumption (kappas 0.70–1.00). Environmental exposures that involved some action by the person, such as pesticide application and use of solvents and metals, also showed high repeatability (kappas>0.78). Lower repeatability was seen for rural residency and bore water consumption (kappa 0.39–0.74). In general, we found that case and control participants provided similar rates of incongruent and missing responses for categorical and continuous occupational, domestic, lifestyle and medical exposures.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Objective The objective of the study was to investigate whether depression is a predictor of postdischarge smoking relapse among patients hospitalized for myocardial infarction (MI) or unstable angina (ILIA), in a smoke-free hospital. Methods Current smokers with MI or UA were interviewed while hospitalized; patients classified with major depression (MD) or no humor disorder were reinterviewed 6 months post discharge to ascertain smoking status. Potential predictors of relapse (depression; stress; anxiety; heart disease risk perception; coffee and alcohol consumption; sociodemographic, clinical, and smoking habit characteristics) were compared between those with MD (n = 268) and no humor disorder (n = 135). Results Relapsers (40.4%) were more frequently and more severely depressed, had higher anxiety and lower self-efficacy scale scores, diagnosis of UA, shorter hospitalizations, started smoking younger, made fewer attempts to quit, had a consort less often, and were more frequently at the `precontemplation` stage of change. Multivariate analysis showed relapse-positive predictors to be MD [odds ratio (OR): 2.549; 95% confidence interval (CI): 1.519-4.275] (P<0.001); `precontemplation` stage of change (OR: 7.798; 95% CI: 2.442-24.898) (P<0.001); previous coronary bypass graft surgery (OR: 4.062; 95% CI: 1.356-12.169) (P=0.012); and previous anxiolytic use (OR: 2.365; 95% CI: 1.095-5.107) (P=0.028). Negative predictors were diagnosis of MI (OR: 0.575; 95% CI: 0.361-0.916) (P=0.019); duration of hospitalization (OR: 0.935; 95% CI: 0.898-0.973) (P=0.001); smoking onset age (OR: 0.952; 95% CI: 0.910-0.994) (P=0.028); number of attempts to quit smoking (OR: 0.808; 95% CI: 0.678-0.964) (P=0.018); and `action` stage of change (OR: 0.065; 95% CI: 0.008-0.532) (P= 0.010). Conclusion Depression, no motivation, shorter hospitalization, and severity of illness contributed to postdischarge resumption of smoking by patients with acute coronary syndrome, who underwent hospital-initiated smoking cessation.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

This in vitro research verified the possibility of eliminating staining caused by coffee and red wine in five composite resins, after being submitted to thermal cycling. Thirty-six specimens were prepared and immersed in water at 37 degrees C for 24 hours. After polishing, specimen color was measured in a spectrophotometer Cintra 10 UV (Visible Spectrometer, GBC, Braeside, VIC, Australia). All specimens were submitted to thermal cycling at temperatures of 5 and 55 degrees C with a dwell time of 1 minute, for 1,000 cycles in a 75% ethanol/water solution. After thermal cycling, the specimens were immersed in water at 37 degrees C until 7 days had elapsed from the time the specimens were prepared. All specimens were then taken to the spectrophotometer for color measurement. The specimens were divided into three groups (N = 12): distilled water (control), coffee, and red wine. For the staining process to occur on only one surface, all the sides, except one, of the surfaces were isolated with white wax. The specimens were immersed in one of the solutions at 37 degrees C for 14 days. The specimens were dried and taken to the spectrophotometer for color measurement. After this, the specimens were submitted to 20 mu m wear three times, and the color was measured after each one of the wear procedures. Calculation of the color difference was made using CIEDE2000 formula. According to the methodology used in this research, it was concluded that the staining caused by coffee and red wine was superficial and one wear of 20 mu m was sufficient to remove the discoloration.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Objectives: We studied the association between cigarette smoking and ovarian cancer in a population-based case-control study. Methods: A total of 794 women with histologically confirmed epithelial ovarian cancer who were aged 18-79 years and resident in one of three Australian states were interviewed, together with 855 controls aged 18-79 years selected at random from the electoral roll from the same states. Information was obtained about cigarette smoking and other factors including age, parity, oral contraceptive use, and reproductive factors. We estimated the relative risk of ovarian cancer associated with cigarette smoking, accounting for histologic type, using multivariable logistic regression to adjust for confounding factors. Results: Women who had ever smoked cigarettes were more likely to develop ovarian cancer than women who had never smoked (adjusted odds ratio (OR) = 1.5; 95% confidence interval (CI) = 1.2-1.9). Risk was greater for ovarian cancers of borderline malignancy (OR = 2.4; 95% CI = 1.4-4.1) than for invasive tumors (OR = 1.7; 95% CI = 1.2-2.4) and the histologic subtype most strongly associated overall was the mucinous subtype among both current smokers (OR = 3.2; 95% CI = 1.8-5.7) and past smokers (OR = 2.3; 95% CI = 1.3-3.9). Conclusions: These data extend recent findings and suggest that cigarette smoking is a risk factor for ovarian cancer, especially mucinous and borderline mucinous types. From a public health viewpoint, this is one of the few reports of a potentially avoidable risk factor for ovarian cancer.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Purpose: This study evaluated the effect of the incorporation of the antimicrobial monomer methacryloyloxyundecylpyridinium bromide (MUPB) on the hardness, roughness, flexural strength, and color stability of a denture base material. Materials and Methods: Ninety-six disk-shaped (14-mm diameter x 4-mm thick) and 30 rectangular (65 x 10 x 3.3 mm(3)) heat-polymerized acrylic resin specimens were divided into three groups according to the concentration of MUPB (w/w): (A) 0%, (B) 0.3%, (C) 0.6%. Hardness was assessed by a hardness tester equipped with a Vickers diamond penetrator. Flexural strength and surface roughness were tested on a universal testing machine and a surface roughness tester, respectively. Color alterations (Delta E) were measured by a portable spectrophotometer after 12 and 36 days of immersion in water, coffee, or wine. Variables were analyzed by ANOVA/Tukey HSD test (alpha = 0.05). Results: The following mean results (+/-SD) were obtained for hardness (A: 15.6 +/- 0.6, B: 14.6 +/- 1.7, C: 14.8 +/- 0.8 VHN; ANOVA: p = 0.061), flexural strength (A: 111 +/- 17, B: 105 +/- 12, C: 88 +/- 12 MPa; ANOVA: p = 0.008), and roughness (A: 0.20 +/- 0.11, B: 0.20 +/- 0.11, C: 0.24 +/- 0.08 mu m; ANOVA: p = 0.829). Color changes of immersed specimens were significantly influenced by solutions and time (A: 9.1 +/- 3.1, B: 14.8 +/- 7.5, C: 13.3 +/- 6.1 Delta E; ANOVA: p < 0.05). Conclusions: The incorporation of MUPB affects the mechanical properties of a denture base acrylic resin; however, the only significant change was observed for flexural strength and may not be critical. Color changes were slightly higher when resin containing MUPB was immersed in wine for a prolonged time; however, the difference has debatable clinical relevance.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Purpose: This study evaluated the effect of different microwave polymerization cycles on the color changes of a microwave-processed denture base resin after accelerated aging and immersion in beverages. Materials and Methods: Specimens of light pink acrylic resin were divided into three groups according to polymerization cycle: (A) 500 W for 3 minutes, (B) 90 W for 13 minutes + 500 W for 90 seconds, and (C) 320 W for 3 minutes + 0 W for 4 minutes + 720 W for 3 minutes. Control groups were a heat-processed acrylic resin (T) and a chemically activated denture repair resin (Q). Eight specimens per group were aged in an artificial aging chamber and evaluated at 20, 192, and 384 hours. Another series of 40 specimens per group were immersed in water, coffee, tea, cola, or red wine and evaluated at 1, 12, and 36 days. Color was measured by a spectrophotometer before and after aging or immersion. Color changes (Delta E) were analyzed by ANOVA/Bonferroni t-test (alpha = 0.05). Results: Mean Delta E (+/- SD) after 384 hours of accelerated aging were (A) 2.51 +/- 0.50; (B) 3.16 +/- 1.09; (C) 2.89 +/- 1.06; (T) 2.64 +/- 0.34; and (Q) 9.03 +/- 0.40. Group Q had a significantly higher Delta E than the other groups. Color changes of immersed specimens were significantly influenced by solutions and time, but the five groups showed similar values. Mean Delta E at 36 days were (water) 1.4 +/- 0.8; (coffee) 1.3 +/- 0.6; (tea) 1.7 +/- 0.5; (cola) 1.4 +/- 0.7; and (red wine) 10.2 +/- 2.7. Results were similar among the five test groups. Conclusions: Color changes of the microwave-polymerized denture base resin tested were not affected by different polymerization cycles after accelerated aging or immersion in beverages. These changes were similar to the conventional heat-polymerized acrylic resin test, but lower than the repair resin after accelerated aging.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Adultos de Cephalonomia stephanoderis Betrem foram detectados em novembro de 2003 durante amostragem de frutos de Coffea canephora Pierre ex A. Froehner danificados por Hypothenemus hampei Ferrari (Coleoptera: Scolytidae) em Ouro Preto D'Oeste, RO (10º45'S e 62º15'W). De janeiro a julho de 2004, o parasitóide foi amostrada mensalmente em 200 frutos danificados por H. hampei. Provavelmente, C. stephanoderis exerça alguma pressão de parasitismo sobre a população da broca-do-café. A ocorrência do parasitóide em condições naturais aponta para outra alternativa de controle biológico de H. hampei em Rondônia. Este é o primeiro registro de C. stephanoderis em plantações de café na Amazônia brasileira.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Rede é o nome dado para se referenciar qualquer forma que seja composta por linhas interligadas por pontos, sendo assim essa denominação é utilizada para participar de nomes e conceitos em diversas área do conhecimento. Na geografia isso não ocorre de forma diferente. As redes geográficas são a denominação dada as ligações feitas no espaço articuladas por pontos, notadamente são usadas para se fazer referência a redes materiais, mas podem ser mais imateriais ou abstratas a depender do objeto de pesquisa e do adjetivo adotado. A noção de redes urbanas nasceu vinculada aos objetos materiais, entretanto com a evolução da técnica passou a abranger objetos cada vez mais virtuais. As redes urbanas são compostas pelo conjunto de cidades, cada qual com sua centralidade representadas por pontos ou nós na rede, e pelas ligações entre elas, rodovias, hidrovias, infovias etc. As cidades que compõem a rede, por mais semelhanças que possam ter entre si, tem diferentes tipos e graus de centralidade, de poder de atração de pessoas, de recursos; sendo uma região de influência singular, que muda de tempos em tempos, face a evolução do território onde se insere. Tanto as centralidades quanto as redes de urbanas estão em constante mudança, necessitando sempre de atualização tornando o estudo das redes e das centralidades uma questão sempre nova; em especial quando considerado um território tão vasto e complexo como o brasileiro. Neste trabalho relatamos os resultados do estudo das especificidades da centralidade da cidade de Viçosa, que está localizada no interior do estado de Minas Gerais, Brasil. Este estudo fez uso de dados numéricos, fotográficos e cartográficos coletados em diversos momentos da evolução do município e da região onde este se insere, que revelaram as mudanças de qualidade e de intensidade na centralidade dessa cidade, hoje tipificada como média ou intermediária, inserida na rede urbana mineira. No período compreendido entre os anos de 1850 e 1930, Viçosa passou de uma inexpressiva localidade rural, a importante centro de produção de café, galgando ganhos políticos nesse período. Seguiu-se um período de menor pujança, por cerca de setenta anos, para depois, na virada do século XX para XXI, ressurgi como uma localidade especializada em oferecer serviços, notadamente vinculados ao ensino superior e à produção de ciência e tecnologia. Essa nova centralidade, ao contrário do que muitas vezes ocorre, não foi fruto nem de um recurso natural inerente ao território e nem, tão pouco, pela atuação de grandes grupos capitalistas. Foi galgado principalmente pela atuação do Estado que construiu ali as bases de uma especialização funcional, através da implantação de uma universidade pública.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

A cultura do cafeeiro sempre ocupou lugar de destaque na economia do país, dada sua importância na área econômica e social, buscando cada vez mais, um mercado diferenciado, com novas tecnologias para a melhoria da qualidade da bebida. A atividade de lavagem e despolpa de frutos do cafeeiro, necessária para a redução do custo de secagem e a melhoria da qualidade de bebida, é geradora de grandes volumes de resíduos sólidos e líquidos, ricos em material orgânico e inorgânico. A água residuária da atividade de beneficiamento do café (ARC) é gerada anualmente em grande volume no Espírito Santo, e aliado aos nutrientes existentes nesse efluente indica a sua viabilidade de reaproveitamento na fertirrigação de culturas agrícolas. O objetivo do presente trabalho foi avaliar o efeito de diferentes doses de água residuária de café no crescimento, na absorção e interação entre nutrientes e no estado nutricional do milho. Para tanto, foi conduzido um experimento em casa de vegetação utilizando-se o delineamento experimental inteiramente casualizado, onde foram aplicadas 7 doses de ARC, com 3 repetições, em unidades experimentais constituídas por vasos com 2 dm³ de solo. As doses foram equivalentes a 0,00, 15,17, 30,35, 45,52, 60,70, 75,87 e 91,05 litros de ARC por m² de solo. Realizou-se a semeadura de cinco sementes de milho híbrido BR 206 por vaso e cinco dias após a germinação das plantas foi feito o desbaste, mantendo-se três plantas por vaso. Aos trinta dias após a germinação determinou-se o diâmetro do caule (DC), área foliar (AF), matéria seca da parte aérea (MSPA), matéria seca do sistema radicular (MSR), relação parte aérea/raiz (MSPA/MSR), razão massa radicular (matéria seca raiz/matéria seca total) e razão área foliar (área foliar/matéria seca total). Na parte aérea das plantas foi determinado os teores dos macronutrientes (N, P, K, Ca, Mg e S). Os dados foram submetidos a análise de variância e as variáveis em função das doses de ARC submetidas a análise de regressão. Para as variáveis dependentes foi calculado o coeficiente de correlação linear de Pearson. A ARC serviu como fonte de nutrientes para as plantas de milho, aumentou o rendimento da maioria das variáveis de crescimento e os teores de N, K e S. Porém diminuiu o teor de Ca, Mg e P da parte aérea das plantas além de indicar que altas doses promovem desbalanceamento na relação entre nutrientes.