Influence from the sulfonate group (RSO(3)(-)) on the conversion process and emission efficiency of poly(p-phenylene vinylene)

The discovery of an alternative route to convert poly(xylyliden tetrahydrothiophenium chloride) (PTHT) into poly(p-phenylene vinylene) (PPV) using dodecylbenzenesulfonate (DBS) has allowed the formation of ultrathin films with unprecedented control of architecture and emission properties. In this work, we show that this route may be performed with several sufonated compounds where RSO(3)(-) replaces the counter-ion (Cl(-)) of PTHT, some of which are even more efficient than DBS. Spin-coating films were produced from PTHT and azo-dye molecules, an azo-polymer and organic salts as counter-ions of PTHT. The effects of the thermal annealing step of PTHT/RSO(3)(-) films at 110 and 230 degrees C were monitored by measuring the absorption and emission spectra. The results indicate that the exchange of the counterion Cl(-) of PTHT by a linear long chain with RSO(3)(-) group is a general procedure to obtain PPV polymer at lower conversion temperature (ca. 110 degrees C) with significant increase in the emission efficiency, regardless of the chemical position and the number of sulfonate groups. With the enhanced emission caused by Congo Red and Tinopal as counter-ions, it is demonstrated that the new synthetic route is entirely generic, which may allow accurate control of conversion and emission properties. (C) 2010 Elsevier B.V. All rights reserved.

Effect of Lithium Nitrate on the Alkali-Silica Reaction Gel

Lithium nitrate has been used to prevent and to mediate the expansion caused by alkali-silica reaction (ASR). However, there is limited information on how it affects the existing reaction products caused by ASR. The aim of the present work is to determine the modifications caused by the LiNO3 treatment on the structure of the gel produced by ASR. ASR gel samples obtained from a concrete dam were exposed to an aqueous solution of lithium nitrate and sodium hydroxide with molar LiNO3/NaOH = 0.74, and the resulting products were analyzed by X-ray diffraction, infrared spectroscopy, and solid-state nuclear magnetic resonance of Si-29, Na-23, and Li-7. The treatment of the gel samples produces significant structural modifications in ASR products. A new amorphous silicate compound incorporating Li+ ions is formed, with an average silicate network that can be described as linear in contrast with the layered structure of the original gel. This elimination of the layered structure after the Li-based treatments may be related to the reduction of the tendency of the gel to expand. Also, several crystalline compounds containing potassium indicate the release of this species from the original ASR gel.

Novel ruthenium complexes as potential drugs for Chagas`s disease: enzyme inhibition and in vitro/in vivo trypanocidal activity

Background and purpose: The discovery of the pharmacological functions of nitric oxide has led to the development of NO donor compounds as therapeutic agents. A new generation of ruthenium NO donors, cis-[Ru(NO)(bpy)(2)L]X(n) , has been developed, and our aim was to show that these complexes are able to lyse Trypanosoma cruzi in vitro and in vivo. Experimental approach: NO donors were incubated with T. cruzi and their anti-T. cruzi activities evaluated as the percentage of lysed parasites compared to the negative control. In vivo, trypanocidal activity was evaluated by observing the levels of parasitaemia, survival rate and elimination of amastigotes in mouse myocardial tissue. The inhibition of GAPDH was monitored by the biochemical reduction of NAD+ to NADH. Key results: The NO donors cis-[Ru(NO)(bpy)(2)L]X(n) presented inhibitory effects on T. cruzi GAPDH (IC(50) ranging from 89 to 153 mu M). The crystal structure of the enzyme shows that the inhibitory mechanism is compatible with S-nitrosylation of the active cysteine (cys166) site. Compounds cis-[Ru(NO)(bpy)(2)imN](PF(6))(3) and cis-[Ru(NO)(bpy)(2)SO(3)]PF(6), at a dose of 385 nmol center dot kg-1, yielded survival rates of 80 and 60%, respectively, in infected mice, and eradicated any amastigotes from their myocardial tissue. Conclusions and implications: The ruthenium compounds exhibited potent in vitro and in vivo trypanocidal activities at doses up to 1000-fold lower than the clinical dose for benznidazole. Furthermore, one mechanism of action of these compounds is via the S-nitrosylation of Cys166 of T. cruzi GAPDH. Thus, these compounds show huge potential as candidates for the development of new drugs for the treatment of Chagas`s disease. This article is commented on by Machado et al., pp. 258-259 of this issue. To view this commentary visit http://dx.doi.org/10.1111/j.1476-5381.2010.00662.x and to view a related paper in this issue by Guedes et al. visit http://dx.doi.org/10.1111/j.1476-5381.2010.00576.x.

Occupational airborne contamination in South Brazil: 2. Oxidative stress detected in the blood of workers of incineration of hospital residues

One of the most useful methods for elimination of solid residues of health services (SRHS) is incineration. However, it also provokes the emission of several hazardous air pollutants such as heavy metals, furans and dioxins, which produce reactive oxygen species and oxidative stress. The present study, which is parallel to an accompanied paper (Avila Jr. et al., this issue), investigated several enzymatic and non-enzymatic biomarkers of oxidative stress in the blood (contents of vitamin E, lipoperoxidation = TBARS, reduced glutathione = GSH, oxidized glutathione = GSSG, and activities of glutathione S-transferase = GST, glutathione reductase = GR, glutathione peroxidase = GPx, catalase = CAT and superoxide dismutase = SOD), in three different groups (n = 20 each) exposed to airborne contamination associated with incineration of SRHS: workers directly (ca. 100 m from the incinerator) and indirectly exposed (residents living ca. 5 km the incineration site), and controls (non-exposed subjects). TBARS and GSSG levels were increased whilst GSH, TG and alpha-tocopherol contents were decreased in workers and residents compared to controls. Increased GST and CAT activities and decreased GPx activities were detected in exposed subjects compared to controls, while GR did not show any difference among the groups. In conclusion, subjects directly or indirectly exposed to SRHS are facing an oxidative insult and health risk regarding fly ashes contamination from SRHS incineration.

Characterization of O(2) ((1)Delta(g))-Derived Oxidation Products of Tryptophan: A Combination of Tandem Mass Spectrometry Analyses and Isotopic Labeling Studies

The fragmentation mechanisms of singlet oxygen [O(2) ((1)Delta(g))]-derived oxidation products of tryptophan (W) were analyzed using collision-induced dissociation coupled with (18)O-isotopic labeling experiments and accurate mass measurements. The five identified oxidized products, namely two isomeric alcohols (trans and cis WOH), two isomeric hydroperoxides (trans and cis WOOH), and N-formylkynurenine (FMK), were shown to share some common fragment ions and losses of small neutral molecules. Conversely, each oxidation product has its own fragmentation mechanism and intermediates, which were confirmed by (18)O-labeling studies. Isomeric WOH lost mainly H(2)O + CO, while WOOH showed preferential elimination of C(2)H(5)NO(3) by two distinct mechanisms. Differences in the spatial arrangement of the two isomeric WOHs led to differences in the intensities of the fragment ions. The same behavior was also found for trans and cis WOOH. FMK was shown to dissociate by a diverse range of mechanisms, with the loss of ammonia the most favored route. MS/MS analyses, (18)O-labeling, and H(2)(18)O experiments demonstrated the ability of FMK to exchange its oxygen atoms with water. Moreover, this approach also revealed that the carbonyl group has more pronounced oxygen exchange ability compared with the formyl group. The understanding of fragmentation mechanisms involved in O(2) ((1)Delta(g))-mediated oxidation of W provides a useful step toward the structural characterization of oxidized peptides and proteins. (J Am Soc Mass Spectrom 2009, 20, 188-197) (C) 2009 Published by Elsevier Inc. on behalf of American Society for Mass Spectrometry

A theoretical and mass spectrometry study of the fragmentation of mycosporine-like amino acids

In the present study, the mycosporine-like amino acids (MAAs) were isolated from the marine red alga Gracilaria tenuistipitata and analysed by high-resolution accurate-mass sequential mass spectrometry (MSn). In addition to the proposed fragmentation mechanism based on the MSn analysis, it is clearly demonstrated that the elimination of mass 15 is a radical processes taking place at the methoxyl substituent of the double bond. This characteristic loss of a methyl radical was studied by theoretical calculations and the homolytic cleavage of the O-C bond is suggested to be dependent on the bond weakening. The protonation site of the MAAs was indicated by analysis of the Fukui functions and the relative Gibbs energies of the several possible protonated forms. (C) 2008 Elsevier B.V. All rights reserved.

Insights into the mechanism of progressive RNA degradation by the archaeal exosome

Initially identified in yeast, the exosome has emerged as a central component of the RNA maturation and degradation machinery both in Archaea and eukaryotes. Here we describe a series of high-resolution structures of the RNase PH ring from the Pyrococcus abyssi exosome, one of them containing three 10-mer RNA strands within the exosome catalytic chamber, and report additional nucleotide interactions involving positions N5 and N7. Residues from all three Rrp41-Rrp42 heterodimers interact with a single RNA molecule, providing evidence for the functional relevance of exosome ring-like assembly in RNA processivity. Furthermore, an ADP-bound structure showed a rearrangement of nucleotide interactions at site N1, suggesting a rationale for the elimination of nucleoside diphosphate after catalysis. In combination with RNA degradation assays performed with mutants of key amino acid residues, the structural data presented here provide support for a model of exosome-mediated RNA degradation that integrates the events involving catalytic cleavage, product elimination, and RNA translocation. Finally, comparisons between the archaeal and human exosome structures provide a possible explanation for the eukaryotic exosome inability to catalyze phosphate-dependent RNA degradation.

Detection and Characterization of Cholesterol-Oxidized Products Using HPLC Coupled to Dopant Assisted Atmospheric Pressure Photoionization Tandem Mass Spectrometry

Oxidation of cholesterol (Ch) by a variety of reactive oxygen species gives rise mainly to hydroperoxides and aldehydes. Despite the growing interest in Ch-oxidized products, the detection and characterization of these products is still a matter of concern. In this work, the main Ch-oxidized products, namely, 3 beta-hydroxycholest-5-ene-7 alpha-hydroperoxide (7 alpha-OOH), 3 beta-5 alpha-cholest-6-ene-5-hydroperoxide (5 alpha-OOH), 3 beta-hydroxycholest-4-ene-6 alpha-hydroperoxide (6 alpha-OOH), 3 beta-hydroxycholest-4-ene-6 beta-hydroperoxide (6 beta-OOH), and 3 beta-hydroxy-5 beta-hydroxy-B-norcholestane-6 beta-carboxaldehyde (ChAld), were detected in the same analysis using high-performance liquid chromatography (HPLC) coupled to dopant assisted atmospheric pressure photoionization tandem mass spectrometry. The use of selected reaction monitoring mode (SRM) allowed a sensitive detection of each oxidized product, while the enhanced product ion mode (EPI) helped to improve the confidence of the analyses. Isotopic labeling experiments enabled one to elucidate mechanistic features during fragmentation processes. The characteristic fragmentation pattern of Ch-oxidized products is the consecutive loss of 1120 molecules, yielding cationic fragments at m/z 401, 383, and 365. Homolytic scissions of the peroxide bond are also seen. With (18)O-labeling approach, it was possible to establish a fragmentation order for each isomer. The SRM transitions ratio along with EPI and (18)O-labeled experiments give detailed information about differences for water elimination, allowing a proper discrimination between the isomers:Phis is of special interest considering the emerging role of Ch-oxidized products in the development of diseases.

Thermal analysis of prednicarbate and characterization of thermal decomposition product

In the present work, the thermal behavior of prednicarbate was studied using DSC and TG/DTG. The solid product remaining at the first decomposition step of the drug was isolated by TG, in air and N(2) atmospheres and was characterized using LC-MS/MS, NMR, and IR spectroscopy. It was found that the product at the first thermal decomposition step of prednicarbate corresponds to the elimination of the carbonate group bonding to C(17), and a consequent formation of double bond between C(17) and C(16). Structure elucidation of this degradation product by spectral data has been discussed in detail.

Lithium butylchalcogenolate induced Michael-aldol tandem sequence: easy and rapid access to highly functionalized organochalcogenides and unsaturated compounds

Lithium ""butylchalcogenolates are generated in situ by reacting the elements (S, Se, and Te) with (n)butyl-lithium at 0 degrees C. Reaction of the lithium alkylchalcogenolates with activated alkenes and aldehydes gives the corresponding aldol adducts. The selenium-containing products give Morita-Baylis-Hillman adducts after the oxidation/elimination of the selenoxide. The whole sequence can be performed in a one-pot procedure. (C) 2009 Elsevier Ltd. All rights reserved.

Gas-Phase Acylium Ion Transfer Reactions Mediated by a Proton Shuttle Mechanism

The mechanism and the energy profile of the gas-phase reaction that mimics esterification under acidic conditions have been investigated at different levels of theory. These reactions are known to proceed with rate constants close to the collision limit in the gas-phase and questions have been raised as to whether the typical addition-elimination mechanism via a tetrahedral intermediate can explain the ease of these processes. Because these reactions are common to many organic and biochemical processes it is important to understand the intrinsic reactivity of these systems. Our calculations at different levels of theory reveal that a stepwise mechanism via a tetrahedral species is characterized by energy barriers that are inconsistent with the experimental results. For the thermoneutral exchange between protonated acetic acid and water and the exothermic reaction of protonated acetic acid and methanol our calculations show that these reactions proceed initially by a proton shuttle between the carbonyl oxygen and the hydroxy oxygen of acetic acid mediated by water, or methanol, followed by displacement at the acylium ion center. These findings suggest that the reactions in the gas-phase should be viewed as an acylium ion transfer reaction. (C) 2010 Wiley Periodicals, Inc. Int J Quantum Chem 111: 1596-1606, 2011

Hybrid photocatalysts for the degradation of trichloroethylene in air

Hybrid photocatalysts based on an adsorbent SiMgOx and a photocatalyst TiO(2) were developed in a plate shape. The ceramic surface was coated with TiO(2) by the slip-casting technique. The effect of the support in the photocatalytic degradation of trichloroethylene (TCE) was analyzed by modifying TiO(2) loading and the layer thickness. Photocatalysts were characterised by N(2) adsorption-desorption, mercury intrusion porosimetry, SEM, UV-vis spectroscopy and XRD. A direct relationship between the TiO(2) content and the photocatalytic activity was observed up to three layers of TiO(2) (0.66 wt.%). Our results indicate that intermediate species generated on the TiO(2) layer can migrate through relatively long distances to react with the OH(-) surface groups of the support. By increasing the TiO(2) loading of the photocatalyst two effects were observed: trichloroethylene conversion is enhanced, while the efficiency of the oxidation process is decreased at expenses of increasing the selectivity to COCl(2) and dichloroacetylchloride (DCAC). The results are discussed in terms of the layer thickness, TiO(2) amount, TCE conversion and CO(2), and COCl(2) selectivity. (C) 2009 Elsevier B.V. All rights reserved.

Investigation of the CO tolerance mechanism at several Pt-based bimetallic anode electrocatalysts in a PEM fuel cell

The electrocatalysis of CO tolerance of Pt/C, PtRu/C, PtFe/C, PtMo/C, and PtW/C at a PEM fuel cell anode has been investigated using single cell polarization and online electrochemical mass spectrometry (EMS) measurements, and cyclic voltammetry, X-ray diffraction (XRD), in situ X-ray absorption near edge structure (XANES) analyses of the electrocatalysts. For all bimetallic electrocatalysts, which presented higher CO tolerance, EMS results have shown that the production of CO(2) start at lower hydrogen electrode overpotentials as compared to Pt/C, confirming the occurrence of the so-called bifunctional mechanism. On the other hand, XANES results indicate an increase in the Pt 5d-band vacancies for the bimetallic catalysts, particulary for PtFe/C, this leading to a weakening of the Pt-CO bond, helping to increase the CO tolerance (the so-called electronic effect). For PtMo/C and PtRu/C supplied with H(2)/CO, the formation of CO(2) is observed even when the cell is at open circuit, confirming some elimination of CO by a chemical process, most probably the water gas shift reaction. (C) 2008 Elsevier Ltd. All rights reserved.

A Contour-based Separation of VerticallyAttached Traffic Signs

This report presents an algorithm for locating the cut points for and separatingvertically attached traffic signs in Sweden. This algorithm provides severaladvanced digital image processing features: binary image which representsvisual object and its complex rectangle background with number one and zerorespectively, improved cross correlation which shows the similarity of 2Dobjects and filters traffic sign candidates, simplified shape decompositionwhich smoothes contour of visual object iteratively in order to reduce whitenoises, flipping point detection which locates black noises candidates, chasmfilling algorithm which eliminates black noises, determines the final cut pointsand separates originally attached traffic signs into individual ones. At each step,the mediate results as well as the efficiency in practice would be presented toshow the advantages and disadvantages of the developed algorithm. Thisreport concentrates on contour-based recognition of Swedish traffic signs. Thegeneral shapes cover upward triangle, downward triangle, circle, rectangle andoctagon. At last, a demonstration program would be presented to show howthe algorithm works in real-time environment.

Björk på åkermark : - beståndsetablering eller betesbeskogning

I ett bestånd med björk, planterad 1990 på nedlagd åkermark i 3x1 m förband har en jämförande studie gjorts. Halva arealen har traditionell skogsproduktion, vilken jämförts med en del med skötsel för kombinerad betesdrift och skogsproduktion. I arbetet redovisas utnyttjad metodik vid anläggning, markbehandling, ogräsbekämpning, stängsling och djurhållning, röjning och gallring, nuvarande och beräknad total produktion, grenrensning samt skador. Tre viktiga regler som har bidragit till den lyckosamma etableringen vid beskogningen av denna betesmark är kontinuerlig ogräsbekämpning, tidig och kraftfull röjning/gallring samt stängsling.In a birch stand established in 1990 on former agricultural land in a 3x1 m spacing a comparative study was made. Half the accerage has ad a traditional silviculture while the other half has been managed aiming at future grace land combined with wood production. In this paper we describe the establishment method used, soil treatment, weed protection, fencing and animal treatment, thinning, productivity and yield, furthermore pruning and occurrence of damages. Three important rules for establishment of silvipastures are continuous weed elimination, early, forceful thinning and good fencing.