Efficient synthesis of benzothiazine and acrylamide compounds

This article describes the synthesis of the new (2Z)-2-(4-methoxybenzylidene)-6-nitro-4H -benzo[1,4]thiazin-3-one, (2Z)-2-(4-methoxybenzylidene)-4-methyl-6-nitro-4H-benzo[1,4]thiazin-3-one, (2Z)-6-amino-2-(4-methoxybenzylidene)-4H -benzo[1,4]thiazin-3-one, (2Z)-6-butylamino-2-(4-methoxybenzylidene)-4-methyl-4H-benzo[1,4]-thiazin-3-one and (2E)-N-alkyl-N-(2-hydroxy-5-nitrophenyl)-3-phenylacrylamides and the spectroscopic data. The arylidenebenzothiazine compounds were prepared using the Knoevenagel condensation with substituted benzaldehydes in the presence of sodium methoxide in DMF. The presence of a nitro substituent in the 4-position, water and a slightly acid reaction medium in this condensation caused the rupture of the benzothiazine ring and subsequent formation of the phenylacrylamide compounds. A crystallographic data was presented for (2E)-3-(4-bromophenyl)-N-dodecyl-N -(2-hydroxy-5-nitrophenyl) acrylamide.

Development of a flow through photo-reactor to study degradation of organic compounds by Sequential Injection Analysis (SIA)

This work describes a photo-reactor to perform in line degradation of organic compounds by photo-Fenton reaction using Sequential Injection Analysis (SIA) system. A copper phthalocyanine-3,4',4²,4²¢-tetrasulfonic acid tetrasodium salt dye solution was used as a model compound for the phthalocyanine family, whose pigments have a large use in automotive coatings industry. Based on preliminary tests, 97% of color removal was obtained from a solution containing 20 µmol L-1 of this dye.

Volatile compounds in the thermoplastic extrusion of bovine rumen

The volatile compounds of raw and extruded bovine rumen, extracted by dynamic headspace, were separated by gas chromatography and analyzed by GC-MS. Raw and extruded materials presented thirty-two volatile compounds. The following compounds were identified in raw bovine rumen: heptane, 1-heptene, 4-methyl-2-pentanone, toluene, hexanal, ethyl butyrate, o-xylene, m-xylene, p-xylene, heptanal, limonene, nonanal, dodecane, tridecane, tetradecane, pentadecane, hexadecane, heptadecane and octadecane. The following compounds were identified in the extruded material: 1-heptene, 2,4-dimethylhexane, toluene, limonene, undecane, tetradecane, pentadecane, hexadecane, heptadecane, octadecane and nonadecane. Mass spectra of some unidentified compounds indicated the presence of hydrocarbons with branched chains or cyclic structure.

Selenium and Mercury in the Brazilian Amazon: Opposing Influences on Age-Related Cataracts

BACKGROUND: Age-related cataracts (ARCs) are an important cause of blindness in developing countries. Although antioxidants may be part of the body's defense to prevent ARC, environmental contaminants may contribute to cataractogenesis. In fish-eating populations of the lower Tapajos region, elevated exposure to mercury (Hg) has been reported, and blood levels of selenium (Se) range from normal to very high (> 1,000 mu g/L). OBJECTIVES: We examined ARCs in relation to these elements among adults (>= 40 years of age) from 12 riverside communities. METHODS: Participants (n = 211) provided blood samples and underwent an extensive ocular examination. Inductively coupled plasma mass spectrometry was used to assess Hg and Se in blood and plasma. RESULTS: One-third (n = 69; 32.7%) of the participants had ARC. Lower plasma Se (P-Se; < 25th percentile, 110 mu g/L) and higher blood Hg (B-Hg; >= 25th percentile, 25 mu g/L) were associated with a higher prevalence odds ratio (POR) of ARC [adjusted POR (95% confidence interval), 2.69 (1.11-6.56) and 4.45 (1.43-13.83), respectively]. Among participants with high P-Se, we observed a positive but nonsignificant association with high B-Hg exposure, whereas among those with low B-Hg, we observed no association for P-Se. However, compared with the optimum situation (high P-Se, low B-Hg), the POR for those with low P-Se and high B-Hg was 16.4 (3.0-87.9). This finding suggests a synergistic effect. CONCLUSION: Our results suggest that persons in this population with elevated Hg, the cataractogenic effects of Hg may be offset by Se. Because of the relatively small sample size and possible confounding by other dietary nutrients, additional studies with sufficient power to assess multiple nutrient and toxic interactions are required to confirm these findings.

Antileishmanial Activity of the Hydroalcoholic Extract of Miconia langsdorffii, Isolated Compounds, and Semi-Synthetic Derivatives

The in vitro activity of the crude hydroalcoholic extract of the aerial parts of Miconia langsdorffii Cogn. was evaluated against the promastigote forms of L. amazonensis, the causative agent of cutaneous leishmaniasis in humans. The bioassay-guided fractionation of this extract led to identification of the triterpenes ursolic acid and oleanolic acid as the major compounds in the fraction that displayed the highest activity. Several ursolic acid semi-synthetic derivatives were prepared, to find out whether more active compounds could be obtained. Among these ursolic acid-derived substances, the C-28 methyl ester derivative exhibited the best antileishmanial activity.

Aspergillus nidulans as a biological system to detect the genotoxic effects of mercury fumes on eukaryotes

Mercury (Hg) pollution is one of the most serious environmental problems. Due to public concern prompted by the symptoms displayed by people who consumed contaminated fish in Minamata, Japan in 1956, Hg pollution has since been kept under constant surveillance. However, despite considerable accumulation of knowledge on the noxious effects of ingested or inhaled Hg, especially for humans, there is virtually nothing known about the genotoxic effects of Hg. Because increased mitotic crossing over is assumed to be the first step leading to carcinogenesis, we used a sensitive short-term test (homozygotization index) to look for DNA alterations induced by Hg fumes. In one Aspergillus nidulans diploid strain (UT448//UT184), the effects of the Hg fumes appeared scattered all over the DNA, causing 3.05 times more recombination frequencies than the mean for other strains. Another diploid (Dp II- I//UT184) was little affected by Hg. This led us to hypothesize that a genetic factor present in the UT184 master strain genome, close to the nicB8 genetic marker, is responsible for this behavior. These findings corroborate our previous findings that the homozygotization index can be used as a bioassay for rapid and efficient assessment of ecotoxicological hazards.

Polar organic marker compounds in atmospheric aerosols during the LBA-SMOCC 2002 biomass burning experiment in Rondonia, Brazil: sources and source processes, time series, diel variations and size distributions

Measurements of polar organic marker compounds were performed on aerosols that were collected at a pasture site in the Amazon basin (Rondonia, Brazil) using a high-volume dichotomous sampler (HVDS) and a Micro-Orifice Uniform Deposit Impactor (MOUDI) within the framework of the 2002 LBA-SMOCC (Large-Scale Biosphere Atmosphere Experiment in Amazonia - Smoke Aerosols, Clouds, Rainfall, and Climate: Aerosols From Biomass Burning Perturb Global and Regional Climate) campaign. The campaign spanned the late dry season (biomass burning), a transition period, and the onset of the wet season (clean conditions). In the present study a more detailed discussion is presented compared to previous reports on the behavior of selected polar marker compounds, including levoglucosan, malic acid, isoprene secondary organic aerosol (SOA) tracers and tracers for fungal spores. The tracer data are discussed taking into account new insights that recently became available into their stability and/or aerosol formation processes. During all three periods, levoglucosan was the most dominant identified organic species in the PM(2.5) size fraction of the HVDS samples. In the dry period levoglucosan reached concentrations of up to 7.5 mu g m(-3) and exhibited diel variations with a nighttime prevalence. It was closely associated with the PM mass in the size-segregated samples and was mainly present in the fine mode, except during the wet period where it peaked in the coarse mode. Isoprene SOA tracers showed an average concentration of 250 ng m(-3) during the dry period versus 157 ng m(-3) during the transition period and 52 ng m(-3) during the wet period. Malic acid and the 2-methyltetrols exhibited a different size distribution pattern, which is consistent with different aerosol formation processes (i.e., gas-to-particle partitioning in the case of malic acid and heterogeneous formation from gas-phase precursors in the case of the 2-methyltetrols). The 2-methyltetrols were mainly associated with the fine mode during all periods, while malic acid was prevalent in the fine mode only during the dry and transition periods, and dominant in the coarse mode during the wet period. The sum of the fungal spore tracers arabitol, mannitol, and erythritol in the PM(2.5) fraction of the HVDS samples during the dry, transition, and wet periods was, on average, 54 ng m(-3), 34 ng m(-3), and 27 ng m(-3), respectively, and revealed minor day/night variation. The mass size distributions of arabitol and mannitol during all periods showed similar patterns and an association with the coarse mode, consistent with their primary origin. The results show that even under the heavy smoke conditions of the dry period a natural background with contributions from bioaerosols and isoprene SOA can be revealed. The enhancement in isoprene SOA in the dry season is mainly attributed to an increased acidity of the aerosols, increased NO(x) concentrations and a decreased wet deposition.

Logarithmic contribution to the electrical resistivity in (Ru(1-x)Ir(x))Sr(2)GdCu(2)O(8) compounds

A systematic study of magnetoresistance and dc magnetization was conducted in polycrystalline (Ru(1-x)Ir(x))Sr(2)GdCu(2)O(8) [(Ru,Ir)-1212] compounds, for 0 <= x <= 0.15. We found that a deviation from linearity in the normal-state electrical resistivity (rho) curves for temperatures below the magnetic transition temperature T(M) < 130 K can be properly described by a logarithmic term. The prefactor C(x, H) of this anomalous ln T contribution to rho(T) increases linearly with the Ir concentration, and diminishes rapidly with increasing applied magnetic field up to H approximate to 4 T, merging with the C(0,H) curve at higher magnetic fields. Correlation with magnetic susceptibility measurements supports a scenario of local perturbations in the orientation of Ru moments induced in the neighborhood of the Ir ions, therefore acting as scattering centers. The linear dependence of the prefactor C(x,H=0) and the superconducting transition temperature T(SC) on x points to a common source for the resistivity anomaly and the reduction in T(SC), suggesting that the CuO(2) and RuO(2) layers are not decoupled.

Two-photon absorption spectra of carotenoids compounds

Carotenoids are biosynthetic organic pigments that constitute an important class of one-dimensional pi-conjugated organic molecules with enormous potential for application in biophotonic devices. In this context, we studied the degenerate two-photon absorption (2PA) cross-section spectra of two carotenoid compounds (beta-carotene and beta-apo-8'-carotenal) employing the conventional and white-light-continuum Z-scan techniques and quantum chemistry calculations. Because carotenoids coexist at room temperature as a mixture of isomers, the 2PA spectra reported here are due to samples containing a distribution of isomers, presenting distinct conjugation length and conformation. We show that these compounds present a defined structure on the 2PA spectra, that peaks at 650 nm with an absorption cross-section of approximately 5000 GM, for both compounds. In addition, we observed a 2PA band at 990 nm for beta-apo-8'-carotenal, which was attributed to a overlapping of I(I)B(u) +-like and 2(I)Ag(-)-like states, which are strongly one- and two-photon allowed, respectively. Spectroscopic parameters of the electronic transitions to singlet-excited states, which are directly related to photophysical properties of these compounds, were obtained by fitting the 2PA spectra using the sum-over-states approach. The analysis and interpretations of the 2PA spectra of the investigated carotenoids were supported by theoretical predictions of one- and two-photon transitions carried out using the response functions formalism within the density functional theory framework, using the long-range corrected CAM-B3LYP functional. (C) 2011 American Institute of Physics. [doi:10.1063/1.3590157]

Experimental and theoretical study of two-photon absorption in nitrofuran derivatives: Promising compounds for photochemotherapy

We report experimental and theoretical studies of the two-photon absorption spectrum of two nitrofuran derivatives: nitrofurantoine, (1-(5-nitro-2-furfurilideneamine)-hidantoine) and quinifuryl, 2-(5`-nitro-2`-furanyl) ethenyl-4-{N-[4`-(N,N-diethylamino)-1`-methylbutyl]carbamoyl} quinoline. Both molecules are representative of a family of 5-nitrofuran-ethenyl-quinoline drugs that have been demonstrated to display high toxicity to various species of transformed cells in the dark. We determine the two-photon absorption cross-section for both compounds, from 560 to 880 nm, which present peak values of 64 GM for quinifuryl and 20 GM for nitrofurantoine (1 GM = 1 x 10(-50) cm(4).s.photon(-1)). Besides, theoretical calculations employing the linear and quadratic response functions were carried out at the density functional theory level to aid the interpretations of the experimental results. The theoretical results yielded oscillator strengths, two-photon transition probabilities, and transition energies, which are in good agreement with the experimental data. A higher number of allowed electronic transitions was identified for quinifuryl in comparison to nitrofurantoine by the theoretical calculations. Due to the planar structure of both compounds, the differences in the two-photon absorption cross-section values are a consequence of their distinct conjugation lengths. (c) 2011 American Institute of Physics. [doi:10.1063/1.3514911]

Theoretical study of one- and two-photon absorption spectra of azoaromatic compounds

In this study, the one- and two-photon absorption spectra of seven azoaromatic compounds (five pseudostilbenes-type and two aminoazobenzenes) were theoretically investigated using the density functional theory combined with the response functions formalism. The equilibrium molecular structure of each compound was obtained at three different levels of theory: Hartree-Fock, density functional theory (DFT), and Moller-Plesset 2. The effect of solvent on the equilibrium structure and the electronic transitions of the compounds were investigated using the polarizable continuum model. For the one-photon absorption, the allowed pi ->pi(*) transition energy showed to be dependent on the molecular structures and the effect of solvent, while the n ->pi(*) and pi ->pi(*)(n) transition energies exhibited only a slight dependence. An inversion between the bands corresponding to the pi ->pi(*) and n ->pi(*) states due to the effect of solvent was observed for the pseudostilbene-type compounds. To characterize the allowed two-photon absorption transitions for azoaromatic compounds, the response functions formalism combined with DFT using the hybrid B3LYP and PBE0 functionals and the long-range corrected CAM-B3LYP functional was employed. The theoretical results support the previous findings based on the three-state model. The model takes into account the ground and two electronic excited states and has already been used to describe and interpret the two-photon absorption spectrum of azoaromatic compounds. The highest energy two-photon allowed transition for the pseudostilbene-type compounds shows to be more effectively affected (similar to 20%) by the torsion of the molecular structure than the lowest allowed transition (similar to 10%). In order to elucidate the effect of the solvent on the two-photon absorption spectra, the lowest allowed two-photon transition (dipolar transition) for each compound was analyzed using a two-state approximation and the polarizable continuum model. The results obtained reveal that the effect of solvent increases drastically the two-photon cross-section of the dipolar transition of the pseudostilbene-type compounds. In general, the features of both one- and two-photon absorption spectra of the azoaromatic compounds are well reproduced by the theoretical calculations.

Short-range structure of Pb(1-x)Ba(x)Zr(0.65)Ti(0.35)O(3) ceramic compounds probed by XAS and Raman scattering techniques

Ti K-edge x-ray absorption near-edge spectroscopy (XANES) and Raman scattering were used to study the solid solution effects on the structural and vibrational properties of Pb(1-x)Ba(x)Zr(0.65)Ti(0.35)O(3) with 0.0 < x < 0.40. Compared with x-ray diffraction techniques, which indicates that the average crystal symmetry changes with the substitution of Pb by Ba ions or with temperature variations for samples with x=0.00, 0.10, and 0.20, local structural probes such as XANES and Raman scattering results demonstrate that at local level, the symmetry changes are much less prominent. Theoretical XANES spectra calculation corroborate with the interpretation of the XANES experimental data.

Effective coordination concept applied for phase change (GeTe)(m)(Sb(2)Te(3))(n) compounds

In this work, we employed the effective coordination concept to study the local environments of the Ge, Sb, and Te atoms in the Ge(m)Sb(2n)Te(m+3n) compounds. From our calculations and analysis, we found an average effective coordination number (ECN) reduction of 1.59, 1.42, and 1.37, for the Ge, Sb, Te atoms in the phase transition from crystalline, ECN=5.55 (Ge), 5.73 (Sb), 4.37 (Te), to the amorphous phase, ECN=3.96 (Ge), 4.31 (Sb), 3.09 (Te), for the Ge(2)Sb(2)Te(5) composition. Similar changes are observed for other compositions. Thus, our results indicate that the coordination changes from the crystalline to amorphous phase are not large as previously assumed in the literature, i.e., from sixfold to fourfold for Ge, which can contribute to obtain a better understanding of the crystalline to amorphous phase transition. (C) 2011 American Institute of Physics. [doi:10.1063/1.3533422]

Total and inorganic mercury determination in fish tissue by flow injection cold vapour atomic fluorescence spectrometry

A simple and reliable method for Hg determination in fish samples has been developed. Lyophilised fish tissue samples were extracted in a 25% (w/v) tetramethylammonium hydroxide (TMAH) solution; the extracts were then analysed by FI-CVAFS. This method can be used to determine total and inorganic Hg, using the same FI manifold. For total Hg determination, a 0.1% (w/v) KMnO(4) solution was added to the FI manifold at the sample zone, followed by the addition of a 0.5% (w/v) SnCl(2) solution, whereas inorganic Hg was determined by adding a 0.1% (w/v) L-cysteine solution followed by a 1.0% (w/v) SnCl(2) solution to the FI system. The organic fraction was determined as the difference between total and inorganic Hg. Sample preparation, reagent consumption and parameters that can influence the FI-CVAFS performance were also evaluated. The limit of detection for this method is 3.7 ng g(-1) for total Hg and 4.3 ng g(-1) for inorganic Hg. The relative standard deviation for a 1.0 mu gL(-1) CH(3)Hg standard solution (n = 20) was 1.1%, and 1.3% for a 1.0 mu gL(-1) Hg(2+) standard solution (n = 20). Accuracy was assessed by the analysis of Certified Reference Material (dogfish: DORM-2, NRCC). Recoveries of 99.1% for total Hg and 93.9% inorganic Hg were obtained. Mercury losses were not observed when sample solutions were re-analysed after a seven day period of storage at 4 degrees C.

Low nanomolar concentration of mercury chloride increases vascular reactivity to phenylephrine and local angiotensin production in rats

Exposure to mercury at nanomolar level affects cardiac function but its effects on vascular reactivity have yet to be investigated. Pressor responses to phenylephrine (PHE) were investigated in perfused rat tail arteries before and after treatment with 6 nM HgCl2 during 1 h,,in the presence (E+) and absence (E-) of endothelium, after L-NAME (10(-4) M), indomethacin (10(-5) M), enalaprilate (1 mu M), tempol (1 mu M) and deferoxamine (300 mu M) treatments. HgCl2 increased sensitivity (pD(2)) without modifying the maximum response (Em) to PHE, but the pD(2) increase was abolished after endothelial damage. L-NAME treatment increased pD(2) and Emax. However, in the presence of HgCl2, this increase was smaller, and it did not modify Emax. After indomethacin treatment, the increase of pD(2) induced by HgCl2 was maintained. Enalaprilate, tempol and deferoxamine reversed the increase of pD(2) evoked by HgCl2. HgCl2 increased the angiotensin converting enzyme (ACE) activity explaining the result obtained with enalaprilate. Results suggest that at nanomolar concentrations HgCl2 increase the vascular reactivity to PHE. This response is endothelium mediated and involves the reduction of NO bioavailability and the action of reactive oxygen species. The local ACE participates in mercury actions and depends on the angiotensin 11 generation. (c) 2007 Elsevier Inc. All rights reserved.