Investigation of the occurrence of pesticide residues in rural wells and surface water following application to tobacco

In this work the exposure of wells and surface water to pesticides, commonly used for tobacco cropping, was assessed. Water consumption wells and surface water flows were sampled at different times. After a preconcentration step with solid phase extraction (SPE), the selected pesticides were determined by gas chromatography with electron capture detection (GC-ECD) or high performance liquid chromatography with diode array detection (HPLC-DAD). No pesticides were detected in the well water samples and surface water flow in the winter season. However, in the spring and summer higher concentrations of chlorpyrifos and imidacloprid were found in the water source samples. Atrazine, simazine and clomazone were also found. The occurrence of pesticides in collected water samples was related with the application to tobacco.

Self-condensation of n-(N-propyl)butanimine: NMR and mass spectral analyses and investigation by theoretical calculation

The stability of N-propylbutanimine (1) was investigated under different experimental conditions. The acid-catalyzed self-condensation that produced the E-enimine (4) and Z-inimine (5) was studied by experimental analyses and theoretical calculations. Since the calculations for the energy of 5 indicated that it had a lower energy than 4, yet 4 was the principal product, the self-condensation of 1 must be kinetically controlled.

Theoretical investigation of electronic excitation transfer between chlorophylls in light-harvesting antenna of photosystem ii using quantum computers

The excitation energy transfer between chlorophylls in major and minor antenna complexes of photosystem II (PSII) was investigated using quantum Fourier transforms. These transforms have an important role in the efficiency of quantum algorithms of quantum computers. The equation 2n=N was used to make the connection between excitation energy transfers using quantum Fourier transform, where n is the number of qubits required for simulation of transfers and N is the number of chlorophylls in the antenna complexes.

A Theoretical investigation of a potential high energy density compound 3,6,7,8-tetranitro-3,6,7,8-tetraaza-tricyclo[3.1.1.1(2,4)]octane

The B3LYP/6-31G (d) density functional theory (DFT) method was used to study molecular geometry, electronic structure, infrared spectrum (IR) and thermodynamic properties. Heat of formation (HOF) and calculated density were estimated to evaluate detonation properties using Kamlet-Jacobs equations. Thermal stability of 3,6,7,8-tetranitro-3,6,7,8-tetraaza-tricyclo [3.1.1.1(2,4)]octane (TTTO) was investigated by calculating bond dissociation energy (BDE) at the unrestricted B3LYP/6-31G(d) level. Results showed the N-NO2 bond is a trigger bond during the thermolysis initiation process. The crystal structure obtained by molecular mechanics (MM) methods belongs to P2(1)/C space group, with cell parameters a = 8.239 Å, b = 8.079 Å, c = 16.860 Å, Z = 4 and r = 1.922 g cm-3. Both detonation velocity of 9.79 km s-1 and detonation pressure of 44.22 GPa performed similarly to CL-20. According to the quantitative standards of energetics and stability, TTTO essentially satisfies this requirement as a high energy density compound (HEDC).

LC-MS/MS method applied to preclinical pharmacokinetic investigation of olanzapine-loaded lipid-core nanocapsules

In spite of different methods reported in the literature to determine olanzapine in biological fluids, all of them used high volumes of plasma. Therefore, the purpose of this paper was to develop an LC-MS/MS method using small plasma volume (0.1 mL) to apply in a preclinical pharmacokinetic investigation. The method was linear over the concentration ranges of 10 - 1000 ng mL-1. Extraction recoveries, stability, and validation parameters were evaluated. Results were within the acceptable limits of international guidelines. A significant decrease in clearance led to a significant 2.26-times increase in AUC0 - 6h of olanzapine-loaded lipid-core nanocapsules compared with free-olanzapine.

Phytochemical investigation of Wissadula periplocifolia (L.) C. Presl and evaluation of its antibacterial activity

A phytochemical study on the aerial parts of Wissadula periplocifolia using chromatographic techniques has led to the isolation of sitosterol (1a), stigmasterol (1b), sitosterol 3-O-β-D-glucopyranoside (2a), stigmasterol 3-O-β-D-glucopyranoside (2b), phaeophytin A (3), 13²-hydroxy-(13²-S)-phaeophytin A (4), phaeophytin B (5), 17³-ethoxyphaeophorbide (6), 3,4-seco-urs-4(23),20(30)-dien-3-oic acid (7), 3-oxo-21β-H-hop-22(29)-ene (8), dammaradienone (9a), and taraxastenone (9b). The isolated compounds were characterised by spectroscopic analysis. A preliminary assay to evaluate the antibacterial activity of W. periplocifolia extracts and fractions showed that the dichloromethane, ethyl acetate, and n-butanol fractions were active against Enterococcus faecalis.

CHEMICAL STUDY OF Hortia superba (Rutaceae) AND INVESTIGATION OF THE ANTIMYCOBACTERIAL ACTIVITY OF CRUDE EXTRACTS AND CONSTITUENTS ISOLATED FROM Hortia SPECIES

In this paper, the chemical study of Hortia superba and antimycobacterial potential of Hortia species were investigated. Crude extracts and limonoids, alkaloids, dihydrocinnamic acid derivatives and coumarins isolated from Hortia superba, Hortia oreadica and Hortia brasiliana were evaluated against Mycobacterium tuberculosis H37Rv, Mycobacterium kansasii and Mycobacterium avium. The results obtained demonstrated an inhibitory effect of the dichloromethane extract of leaves of H. oreadica (MIC 31.25 µg mL-1), indolequinazoline (15.62 µg mL-1) and furoquinoline (31.25 µg mL-1) alkaloids, and dihydrocinnamic acid derivatives (62.50 µg mL-1), on the growth of M. tuberculosis. These results are promising in relation to the search for biologically active natural products and could be useful in the development of effective new drugs against mycobacteria.

Experimental and theoretical investigation of the IR spectra and thermochemistry of four isomers of 2-N,N-dimethylaminecyclohexyl 1-N',N'-dimethylcarbamate

A combined experimental and Density functional theory (DFT) B3LYP/6-311+G* study on the IR spectra of four stable isomers of 2-N,N-dimethylaminecyclohexyl 1-N',N'-dimethylcarbamate was performed. Our theoretical calculations reveal that two new isomers of this compound exist and may be more stable than the known isomers. In addition the entropy, heat capacity, and the enthalpy content of the stable isomers are computed by fitting the calculated data to a standard Shomate equation and IR spectra for the two new isomers are presented.

Serological investigation and PCR in detection of pathogenic leptospires in snakes

Detection of Leptospira by PCR had not yet been described in snakes. This study investigated, by microscopic agglutination test (MAT) and PCR, the presence of antibodies to Leptospira spp. and Leptospira spp., respectively, in venomous and non-venomous wildlife and captivity snakes. All snakes were divided into three groups to be compared: Group 1 (wildlife snakes - WS); Group 2 (snakes in intensive captivity - IC), and Group 3 (collective semi-extensive captivity -CC). Of the 147 snakes studied, 52 (35.4%) were positive for leptospirosis by MAT, 8 (15.4%) belonging to Group 1 (WS), 34 (65.4%) to Group 2 (IC) and 10 (19.2%) to Group 3 (CC). Jararaca (Bothrops jararaca) presented the highest average titer (66.7%, N=22/33) among the three group studied, and Hardjo prajtino was the most prevalent serovar (88.5%, N=46/52), with titers varying from 100 to 3200. Leptospira interrogans was revealed by PCR in kidney and liver of caiçaca (Bothrops moojeni) and jararaca-pintada (Bothrops pauloensis), showing 100% and 93% identity respectively. Future studies should be carried out for better understanding of the role of snakes as a reservoir of Leptospira in nature.

An experimental investigation of the effects of nozzle ellipticity on the flow structure of co-flow jet diffusion flames

The flow structure of cold and ignited jets issuing into a co-flowing air stream was experimentally studied using a laser Doppler velocimeter. Methane was employed as the jet fluid discharging from circular and elliptic nozzles with aspect ratios varying from 1.29 to 1.60. The diameter of the circular nozzle was 4.6 mm and the elliptic nozzles had approximately the same exit area as that of the circular nozzle. These non-circular nozzles were employed in order to increase the stability of attached jet diffusion flames. The time-averaged velocity and r.m.s. value of the velocity fluctuation in the streamwise and transverse directions were measured over the range of co-flowing stream velocities corresponding to different modes of flame blowout that are identified as either lifted or attached flames. On the basis of these measurements, attempts were made to explain the existence of an apparent optimum aspect ratio for the blowout of attached flames observed at higher values of co-flowing stream velocities. The insensitivity of the blowout limits of lifted flames to nozzle geometry observed in our previous work at low co-flowing stream velocities was also explained. Measurements of the fuel concentration at the jet centerline indicated that the mixing process was enhanced with the 1.38 aspect ratio jet compared with the 1.60 aspect ratio jet. On the basis of the obtained experimental data, it was suggested that the higher blowout limits of attached flames for an elliptic jet of 1.38 aspect ratio was due to higher entrainment rates.

Numerical and experimental investigation of thermal louvers for space applications

Thermal louvers, using movable or rotating shutters over a radiating surface, have gained a wide acceptance as highly efficient devices for controlling the temperature of a spacecraft. This paper presents a detailed analysis of the performance of a rectangular thermal louver with movable blades. The radiative capacity of the louver, determined by its effective emittance, is calculated for different values of the blades opening angle. Experimental results obtained with a prototype of a spacecraft thermal louver show good agreement with the theoretical values.

Investigation on diamond turning of silicon crystal - generation mechanism of surface cut with worn tool

This paper discusses the effect of tool wear on surface finish in single-point diamond turning of single crystal silicon. The morphology and topography of the machined surface clearly show the type of cutting edge wear reproduced onto the cutting grooves. Scanning electron microscopy is used in order to correlate the cutting edge damage and microtopography features observed through atomic force microscopy. The possible wear mechanisms affecting tool performance and surface generation during cutting are also discussed. The zero degree rake angle single point diamond tool presented small nicks on the cutting edge. The negative rake angle tools presented more a type of crater wear on the rake face. No wear was detected on flank face of the diamond tools.

An Investigation into Mechanisms of Loss of Safe Basins in a 2 D.O.F. Nonlinear Oscillator

In this work we consider the transient stability of coupled motions of a 2 D.O.F. nonlinear oscillator that can represent, for example, the motions of a sea vessel under the action of trains of regular lateral waves. Instability is studied as the escape of the system from a safe potential well. The set of initial conditions in phase space that lead to acceptable motions constitutes its safe basin. We investigate the evolution of these safe basins under variation of parameters such as frequency and amplitude of waves, and an internal tuning parameter. Complex nonlinear phenomena are known to play an important role in determining the loss of safe basins as, say, wave amplitude is increased. We therefore investigate those processes, and attempt to classify them in terms of their speed relative to changes in parameter values. "Mechanism basins" are produced depicting regions of parameter space in which rapid or slow losses of safe basin are observed. We propose that a comprehensive understanding of mechanisms of loss of safe basins can be a valuable tool in assessing stability properties of these systems, and we give a conceptual view of how such information could be used.

Effects of condensation in microchannels with a porous boundary: analytical investigation on heat transfer and meniscus shape

In two-phase miniature and microchannel flows, the meniscus shape must be considered due to effects that are affected by condensation and/or evaporation and coupled with the transport phenomena in the thin film on the microchannel wall, when capillary forces drive the working fluid. This investigation presents an analytical model for microchannel condensers with a porous boundary, where capillary forces pump the fluid. Methanol was selected as the working fluid. Very low liquid Reynolds numbers were obtained (Re~6), but very high Nusselt numbers (Nu~150) could be found due to the channel size (1.5 mm) and the presence of the porous boundary. The meniscus calculation provided consistent results for the vapor interface temperature and pressure, as well as the meniscus curvature. The obtained results show that microchannel condensers with a porous boundary can be used for heat dissipation with reduced heat transfer area and very high heat dissipation capabilities.