64 resultados para compound semiconductors
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Histamine release from guinea pig heart treated with compound 48/80 was potentiated by the cyclooxygenase inhibitors indomethacin and piroxicam but not by aspirin or phenylbutazone. This differential effect suggests that the potentiation is not merely due to an inhibition of prostaglandin synthesis. Piroxicam potentiated the histamine release induced by cardiac anaphylaxis whereas indomethacin reduced this effect. The SRS-A antagonist FPL 55712 inhibited histamine release induced by cardiac anaphylaxis, but not that evoked by compound 48/80, and also prevented the potentiation due to indomethacin and piroxicam. In total, these data suggest that the potentiation of histamine release by piroxicam and indomethacin is probably due to a diversion of arachidonic acid metabolism from the cyclooxygenase to the lipoxygenase pathways. The resulting lipoxygenase products may then regulate histamine release, with the secretion due to antigen being more sensitive to such modulation than that evoked by compound 48/80.
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Cassava is a widely grown root crop which accumulates two cyanogenic glucosides, linamarin and lotaustralin. Linamarin accounts for more than 80% of the cassava cyanogenic glucosides. It is a β-glucoside of acetone cyanohydrin and ethyl-methyl-ketone-cyanohydrin. Linamarin β-linkage can only be broken under high pressure, high temperature and use of mineral acids, while its enzymatic break occurs easily. Linamarase, an endogenous cassava enzyme, can break this β-linkage. The enzymatic reaction occurs under optimum conditions at 25°C, at pH 5.5 to 6.0. Linamarin is present in all parts of the cassava plant, being more concentrated on the root and leaves. If the enzyme and substrate are joined, a good detoxification can occur. All the cassava plant species are known to contain cyanide. Toxicity caused by free cyanide (CN-) has already been reported, while toxicity caused by glucoside has not. The lethal dose of CN- is 1 mg/kg of live weight; hence, cassava root classification into toxic and non-toxic depending on the amount of cyanide in the root. Should the cyanide content be high enough to exceed such a dose, the root is regarded as toxic. Values from 15 to 400 ppm (mg CN-/kg of fresh weight) of hydrocyanic acid in cassava roots have been mentioned in the literature. However, more frequent values in the interval 30 to 150 ppm have been observed. Processed cassava food consumed in Brazil is safe in regard to cyanide toxicity.
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We present a theoretical description of ligand field effects in the di-μ-azido- bis[{azido(N,N-diethylethylenediamine)} copper(II)] compound by the Simple Overlap Model. The ligand field Hamiltonian is expressed in terms of irreducible tensor operators for an assumed D3h site symmetry occupied by the copper ion. The ligand field parameters, calculated from the available structural data, indicate that the copper ion is under the influence of a very strong ligand field. The energy of the d-d absorption band is well reproduced phenomenologically by the model.
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A new palladium chelate compound is described for the determination of sulfide in aqueous samples. The reagent, bis(2-aminobenzoate)palladium(II) (PdA 2), was prepared by reaction of tetrachloropalladate (PdCl 4 -) with 2-aminobenzoic acid. The compound was characterized by infrared spectroscopy and CHN elemental analysis. The measurement was based on the selective reaction of PdA 2 with sulfide in an aqueous medium, which quantitatively produced fluorescent 2-aminobenzoate (λ ex=245nm, λ em=410nm). The analytical response was linear in the range 0.10-20.0μmol (S 2-) L -1 (r>0.99), with a limit of detection of 0.075μmolL -1 and repeatability (RSD) of 3.4%. There was no interference from CO 3 2-, NO 3 -, Cl -, SO 4 2-, Br -, NO 2 -, K +, NH 4 +, Na +, citrate or S 2O 8 2-. The fluorescence intensity decreased in the presence of H 3CCOO -, PO 4 3- and SCN -, while OH - caused a positive interference. The new fluorescent compound was successfully applied for the determination of sulfide in synthetic wastewater and natural water sample. The advantages of the proposed palladium chelate are absence of toxic by-products, simple synthesis procedure of reagent and yield reaction of about 85%, easy handling and fast acquirement of analytical signal. © 2012 Elsevier B.V.
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Sugarcane bagasse was pretreated with ozone to increase lignocellulosic material digestibility. Bagasse was ozonated in a fixed bed reactor at room temperature, and the effect of the two major parameters, ozone concentration and sample moisture, was studied. Acid insoluble and total lignin decreased whereas acid soluble lignin increased in all experiments. Pretreatment barely attacked carbohydrates, with cellulose and xylan recovery rates being >92%. Ozonolysis increased fermentable carbohydrate release considerably during enzymatic hydrolysis. Glucose and xylose yields increased from 6.64% and 2.05%, for raw bagasse, to 41.79% and 52.44% under the best experimental conditions. Only xylitol, lactic, formic and acetic acid degradation compounds were found, with neither furfural nor HMF (5-hydroxymethylfurfural) being detected. Washing detoxification provided inhibitor removal percentages above 85%, increasing glucose hydrolysis, but decreasing xylose yield by xylan solubilization. SEM analysis showed structural changes after ozonization and washing. © 2013 Elsevier Ltd.
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One of the most important subjects of debate in the formation of the solar system is the origin of Earth's water. Comets have long been considered as the most likely source of the delivery of water to Earth. However, elemental and isotopic arguments suggest a very small contribution from these objects. Other sources have also been proposed, among which local adsorption of water vapor onto dust grains in the primordial nebula and delivery through planetesimals and planetary embryos have become more prominent. However, no sole source of water provides a satisfactory explanation for Earth's water as a whole. In view of that, using numerical simulations, we have developed a compound model incorporating both the principal endogenous and exogenous theories, and investigating their implications for terrestrial planet formation and water delivery. Comets are also considered in the final analysis, as it is likely that at least some of Earth's water has cometary origin. We analyze our results comparing two different water distribution models, and complement our study using the D/H ratio, finding possible relative contributions from each source and focusing on planets formed in the habitable zone. We find that the compound model plays an important role by showing greater advantage in the amount and time of water delivery in Earth-like planets. © 2013. The American Astronomical Society. All rights reserved.
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Iron (Fe) is essential for chlorophyll formation and plant growth. Irondeficiency chlorosis is a major nutritional disorder in several fruit trees cultivated in calcareous and alkaline soils, reducing fruit yield and quality and causing heavy economic losses. Since chelated Fe, the most widespread fertilizers used for preventing or curing Fe deficiency, pose risks of environmental pollution, the development of sustainable agronomic alternatives represents a priority for the fruit industry. In this work, we investigated the effectiveness of a bovine blood-derived product (BB; 0,125% Fe) for preventing Fe-deficiency in grapevine plants. During the vegetative season 2011 potted plants of five graft combinations: Sangiovese/S4O, Cabernet Sauvignon/S4O and Cabernet Sauvignon/140 Ruggeri, 140 Ruggeri/Cabernet Sauvignon, Vitis riparia/Cabernet Sauvignon were grown on calcareous soil. Soil treatments included: 1) Control; 2) Fe-EDDHA (Fe 6%); 3) Bovine-Blood (5 g/L); 4) Bovine-Blood (20 g/L). With the exception of Cabernet Sauvignon/S4O plants, Fe-EDDHA increased SPAD units (leaf chlorophyll content). Bovine-blood at low concentrations had similar or higher SPAD units than Fe-EDDHA. Increasing concentration resulted in further increases in SPAD units only in some graft combinations. Data highlight the efficiency of Fe blood-compound in the prevention of grapevine Fe-deficiency over one growing season.
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Background: Brown propolis is the major type of propolis found in Cuba; its principal component is nemorosone, the major constituent of Clusia rosea floral resins. Nemorosone has received increasing attention due to its strong in vitro anti-cancer action. The citotoxicity of nemorosone in several human cancer cell lines has been reported and correlated to the direct action it has on the estrogen receptor (ER). Breast cancer can be treated with agents that target estrogen-mediated signaling, such as antiestrogens. Phytoestrogen can mimic or modulate the actions of endogenous estrogens and the treatment of breast cancer with phytoestrogens may be a valid strategy, since they have shown anti-cancer activity.Methods: The aim of the present investigation was to assess the capacity of nemorosone to interact with ERs, by Recombinant Yeast Assay (RYA) and E-screen assays, and to determine by comet assay, if the compound causes DNA-damaging in tumoral and non-tumoral breast cells.Results: Nemorosone did not present estrogenic activity, however, it inhibited the 17-β-estradiol (E2) action when either of both methods was used, showing their antiestrogenicity. The DNA damage induced by the benzophenone in cancer and normal breast cells presented negative results.Conclusion: These findings suggest that nemorosone may have therapeutic application in the treatment of breast cancer. © 2013 Camargo et al.; licensee BioMed Central Ltd.
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We present results of ultrasonic measurements on a single crystal of the distorted diamond-chain compound azurite Cu-3(CO3)(2)(OH)(2). Pronounced elastic anomalies are observed in the temperature dependence of the longitudinal elastic mode c(22) which can be assigned to the relevant magnetic interactions in the system and their couplings to the lattice degrees of freedom. From a semiquantitative analysis of the magnetic contribution to c(22) the magnetoelastic coupling G = partial derivative J(2)/partial derivative epsilon(b) can be estimated, where J(2) is the intradimer coupling constant and epsilon(b) the strain along the intrachain b axis. We find an exceptionally large coupling constant of | G| similar to 3650 K highlighting an extraordinarily strong sensitivity of J(2) against changes of the b-axis lattice parameter. These results are complemented by measurements of the hydrostatic pressure dependence of J2 by means of thermal expansion and magnetic susceptibility measurements performed both at ambient and finite hydrostatic pressure. We propose that a structural peculiarity of this compound, in which Cu2O6 dimer units are incorporated in an unusually stretched manner, is responsible for the anomalously large magnetoelastic coupling.
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The complexity of biological samples poses a major challenge for reliable compound identification in mass spectrometry (MS). The presence of interfering compounds that cause additional peaks in the spectrum can make interpretation and assignment difficult. To overcome this issue, new approaches are needed to reduce complexity and simplify spectral interpretation. Recently, focused on unknown metabolite identification, we presented a new approach, RANSY (ratio analysis of nuclear magnetic resonance spectroscopy; Anal. Chem. 2011, 83, 7616-7623), which extracts the signals related to the same metabolite based on peak intensity ratios. On the basis of this concept, we present the ratio analysis of mass spectrometry (RAMSY) method, which facilitates improved compound identification in complex MS spectra. RAMSY works on the principle that, under a given set of experimental conditions, the abundance/intensity ratios between the mass fragments from the same metabolite are relatively constant. Therefore, the quotients of average peak ratios and their standard deviations, generated using a small set of MS spectra from the same ion chromatogram, efficiently allow the statistical recovery of the metabolite peaks and facilitate reliable identification. RAMSY was applied to both gas chromatography/MS and liquid chromatography tandem MS (LC-MS/MS) data to demonstrate its utility. The performance of RAMSY is typically better than the results from correlation methods. RAMSY promises to improve unknown metabolite identification for MS users in metabolomics or other fields.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Biological security and the absence of residues in meat Effectiveness, and/or eggs must be considered when recommending options for the control Alphitobius diaperinus in poultry production environments. This research study evaluated the effectiveness of cypermethrin+chlorpyrifos+citronellal in the control of A. diaperinus, including analysis for the presence of residues of this compound in poultry carcasses (experimental farm). Two studies were carried out under laboratory conditions. One used paper filters a four dilutions of the compound, and the other used a container including with pulverized broiler litter and the compound. The analysis of carcasses for residues was conducted in broilers that raised in a broiler house treated (floor and/or litter) with the compound at a dilution of 1:800. Birds were regularly sacrificed, submitted to necropsy, and liver, muscle and fat fragments were collected. Gas chromatography was used to identify the possible presence of any chemical residue in these samples. High effectiveness rates against A.diaperinus were observed in the two laboratory studies, as well as the absence of residues in the carcasses. This compound, can be recommended as a valuable used in the studied concentrations, alternative for the control and treatment of A. diaperinus.