A fuzzy knowledge-based model for assessing risk of pesticides into the air in cropping systems.

Pesticide use in current cropping systems has become a key input to improve productivity. However, their potential risk to nature demands tools for designing a sustainable use. In this work, a fuzzy knowledge-based model was developed for assessing risk of pesticides into the air. The model was based on fuzzy logic theory which provides a means for representing uncertainty by including knowledge about different processes related to pesticide dynamics using functions, control rules and logical inference systems. All these elements were built through a literature review. Results from the sensitivity analysis on the final model structure showed that the Henry's law constant was the most influential input variable related to the active ingredient identity, while the most influential management and environmental input variables on the pesticide air risk values were the droplet size together with the application method and the current wet bulb temperature depression value, respectively. Results from an independent model validation showed a significant goodness-of-fit between the simulated risk of drift and volatilization and the observed values under experimental conditions. Long-term simulations in a real soybean production system in Argentina showed results of drift reduction in post-emergence conditions of the crop under aerial application condition, and a significant effect of the identity of the active ingredient in the risk values. Simulated risk values from the developed model allow to identify ex ante the combination of agronomic decisions, together with environmental conditions that can reduce the risk of pesticides in the air in real production systems. Further combination with ecotoxicological classification tools should improve pesticide use assessment in agricultural systems.

Geological and hydrogeological review of a semi-arid region with conflicts to water availability (southeastern Brazil).

Groundwater consumption has become increasingly relevant for urban development. The city of Montes Claros (Minas Gerais, Brazil) is located in the border region of the Brazilian semi-arid polygon and has registered conflicts of water use for decades ago. The study area contains a complex karst system responsible for the heterogeneous permeability of water recharge and groundwater flow. The urban area of Montes Claros is located in the Vieira River watershed and contains different groundwater wells used to agro-industrial and human consumption. Almost groundwater captions have a low specific capacity with a consequent groundwater depletion. On the region, there are significant areas with a negative water balance concerning to water recharge and groundwater exploitation. Groundwater flow has a regional dominant direction of SW-NE, however locally, groundwater flow varies and could be identified some clusters with high hydrological potential. The contrast between hydrogeological features of the outcropping lithotypes added to the geological structures contribute to variations in the potentiometric level and in the productivity of aquifers. The main aim of this study is a reviewer of the regional hydrogeology of the municipality of Montes Claros to evaluate a potential groundwater availability on the urban area and minimize a groundwater overexploitation and scarcity. A detailed characterization of the local hydrogeology from Montes Claros region will be crucial to a definition of more efficient water supply policies on the management of water resources, particularly in a scenario of climate change and water scarcity in semi-arid areas.

Rhodamine B oxidation promoted by P450-bioinspired Jacobsen catalysts/cellulose systems.

In this work, we investigated the preparation of P450-bioinspired Mn(iii)-Schiff base complexes supported on DEAE-cellulose ((R,R)-Jacobsen/Cell(NEt2) and (S,S)-Jacobsen/Cell(NEt2), respectively) to oxidize substrates of biological interest. Catalysts were characterized by several physical techniques. UV-Vis spectroscopy with diffuse reflectance (DR/UV-Vis) analysis featured peculiar electronic transitions for both complexes. Fourier transform infrared (FTIR) spectra evidenced the characteristic band of imine groups (HC[double bond, length as m-dash]N) for bioinspired/Cell(NEt2) materials. Immobilization ratios in cellulose fibres were confirmed by atomic absorption spectroscopic (GF-AAS) analyses. Catalytic essays were conducted during rhodamine B (RhB) oxidation. Supported materials attained oxidative yields close to those of homogeneous systems, and cellulose may be stabilizing the active intermediate catalytic species. Reactions may be driven through two different intermediates: MnV(O) and MnIII(O-OH)salen. Homogeneous reactions suggest an asymmetric catalysis. Heterogeneous system reaction yields are similar, and salen complexes anchored on cellulose conformation would interfere on complex intermediate species configuration. The four possible RhB-oxidation products obtained by the reaction with the homogeneous (S,S)-Jacobsen catalyst and meta-chloroperoxybenzoic acid (m-CPBA) system were suggested by 1H NMR analysis, and a catalytic mechanism was proposed.

Historical trends of the ecotoxicological pesticide risk from the main grain crops in Rolling Pampa (Argentina).

We showed the results of the first long-term analysis (1987-2019) of pesticide (herbicides, fungicides and insecticides) impact in the Rolling Pampa, one of the main agricultural areas of Argentina. Using a clear and meaningful tool, based not only on acute toxicity but also on scaling up the results to total sown area, we identified time trends for both pesticide impact and the ecoefficiency of modal pesticide profiles. By the end of the time series, soybean showed a pesticide impact four times greater than maize crop in the studied area. However, the time trend in the subperiod (2012-2019) showed a sustainable pattern of pesticide use in soybean crop, with an improvement in its ecoefficiency. Oppositely, maize showed a relatively constant ecoefficiency value during most of the time series, suggesting a possible path towards an unsustainable cropping system. Findings from this study suggest that some efforts have to be made to improve the pest management decisions towards a more efficient pesticide profiles in maize crop and to keep improving the ecotoxicity pesticide profile in soybean crops because of its large sown area in the studied area.

Leaching and persistence of ametryn and atrazine in red-yellow latosol.

This study evaluated the mobility and persistence of atrazine and ametryn in red-yellow latosols using polyvinyl chloride columns with a diameter of 100 mm and a height of 15 cm. The assays simulated 60-mm rainfall events at 10-day intervals for 70 days. The persistence and leaching were evaluated for these two herbicides. The analytes obtained from the samples were quantified by gas chromatography using flame ionization detection. Compared with ametryn, atrazine showed a greater potential to reach depths below 15 cm over 30 days of simulated rain. Ametryn, however, showed greater persistence in soil at 70 days after application. The persistence of atrazine and ametryn in soil under sunlight was 10 and 144 days respectively. Atrazine was more susceptible to sunlight than ametryn because sunlight favored atrazine degradation in hydroxyatrazine. The results indicate that in red-yellow latosol, atrazine has a high leaching potential in short term, but that ametryn is more persistent and has a high leaching potential in long term.

Imidazole and imidazolium porphyrins: gas-phase chemistry of multicharged ions.

Electrospray ionization mass spectrometry/mass spectrometry in the positive ion mode was used to investigate the gas-phase chemistry of multicharged ions from solutions of porphyrins with 1,3-dimethylimidazolium-2-yl (DMIM) and 1-methylimidazol-2-yl (MIm) meso-substituents. The studied compounds include two free bases and 12 complexes with transition metals (Cu(II), Zn(II), Mn(III), and Fe(III)). The observed multicharged ions are either preformed or formed during the electrospraying process by reduction or protonation and comprise closed-shell and hypervalent mono-radical and bi-radical ions. The observed extensive and abundant fragmentation of the DMIM and MIm meso-substituents is a characteristic feature of these porphyrins. Fragments with the same mass values can be lost from the meso-substituents either as charged or neutral species and from closed-shell and hypervalent radical ions. Reduction processes are observed for both the free bases and the metallated DMIM porphyrins and occur predominantly by formation of hypervalent radicals that fragment, at low energy collisions, by loss of methyl radicals with formation of the corresponding MIm functionalities. These findings confirm that, when using electrospray ionization, reduction is an important characteristic of cationic meso-substituted tetrapyrrolic macrocycles, always occurring when delocalization of the formed hypervalent radicals is possible. For the Fe(III) and Mn(III) complexes, reduction of the metal centers is also observed as the predominant fragmentation of the corresponding reduced ions through losses of charged fragments testifies. The fragmentation of the closed-shell ions formed by protonation of the MIm porphyrins mirrors the fragmentation of the closed-shell ions of their DMIM counterparts.

Spectroscopic properties and singlet oxygen production by the compound ethyl 3,12-dioxopyran[3,2-a]xanthone-2-carboxylate.

The steady state and time resolved experiments together with absorption and emission spectroscopies and quantum chemical calculations have been employed to investigate spectroscopic properties of a xanthone-type compound (ethyl 3,12-dioxopyran[3,2-a]xanthone-2-carboxylate). The spectroscopic data show good agreement with results obtained from quantum chemical calculations. Additionally, this compound shows expressive quantum efficiency for triplet population and a quantum efficiency of singlet oxygen generation very close to unity. Correlations between the nature of singlet and triplet excited states and spectroscopic properties were performed in order to understand the high quantum efficiency of singlet oxygen generation by this compound.

Synthesis and spectroscopic characterization of two tetrasubstituted cationic porphyrin derivatives.

An imidazolium tetrasubstituted cationic porphyrin derivative (the free base and its Zn(II) complex) with five-membered heterocyclic groups in the meso-positions were synthesized using microwave irradiation, and the compounds obtained characterized by (1)H-NMR and mass spectrometry. We observed that under microwave irradiation the yield is similar to when the synthesis is performed under conventional heating, however, the time required to prepare the porphyrins decreases enormously. In order to investigate the electronic state of these compounds, we employed UV-Vis and fluorescence spectroscopy combined with quantum chemical calculations. The results reveal the presence, in both compounds, of a large number of electronic states involving the association between the Soret and a blue-shifted band. The Soret band in both compounds also shows a considerable solvent dependence. As for emission, these compounds present low quantum yield at room temperature and no solvent influence on the fluorescence spectra was observed.

Solvent effects on the photophysics of 3-(benzoxazol-2-yl)-7-(N,N-diethylamino)chromen-2-one.

The photophysics of 3-(benzoxazol-2-yl)-7-(N,N-diethylamino)chromen-2-one was studied in different solvents and in SDS micelles. This compound presents characteristics which include an S(0)---> S(1) ( pi,pi*) transition with a (1)(n,pi*) perturbative component, due to the electronic coupling between the diethylamino group and the coumarin ring, considerable solvatochromism, dual fluorescence and high fluorescence quantum yields in almost all solvents studied. The electronic structure of the S(1) and S(2) excited states permits vibronic coupling between them, making configurational changes of the S(2) excited state possible, leading to the formation of an S(2)(TICT) state. Analysis of the TCSPC data indicates an equilibrium between the S(2)(TICT) and S(1)(LE) states in favour of the former. In protic solvents, the hydrogen bonding between the solvent and the diethylamino moiety results in the formation of an S(2)(HICT) state, making internal conversion an important deactivation process. Quantum mechanical calculations for the isolated molecule show that the diethylamino group in the S(2)(TICT) state is twisted at least 56 degree from the plane of the coumarin ring, with partial electronic decoupling between -NEt(2) and the coumarin ring. This twisting angle must be positively influenced by solute-solvent interactions. [capital Phi](ST) is found to be small, but not negligible. However, Phi (delta) can be considered negligible, an indication that T(1) is a short-lived state. Based on the experimental data and theoretical calculations, the most probable sequence for the first excited states, including the TICT state, is T(1)(n, pi*) < S(2)(TICT) < S(1)(pi,pi*) approximate S(2) (n,pi*).

Not telling the truth in the patient-physician relationship.

The presence of truth and honesty is a permanent demand, and becomes vital the more committed and intimate a relationship is. Medical practice is relevant to this discussion when one questions whether or not a physician should always tell their patient the truth in the face of a progressive or potentially fatal disease, regarding their diagnosis, outcome, therapy and evolution of the specific disease. From this discussion we aim, with the present report, to look at the truth applicable to the patient-physician relationship, and its ethical and moral implications; and also to look at where the Brazilian Code of Medical Ethics (BCME) and the medical literature stand regarding this issue. One concludes that there are only two moments not to tell a patient the truth: when the patient does not want to be informed, and when the truth could be iatrogenic. The question now is, when would the truth be iatrogenic? Physicians, in our opinion, would not be able to judge solitarily when the truth might be deleterious to their patient. Alternatively, we proposed the appointment of a multidisciplinary commission to help the doctor with such a decision.