997 resultados para C .net
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N-3-(1-Methylindol-3-yl)propan-N-(2,2,2-trichloroethoxysulfonyl)guanidine was synthesized from 3-formyl-1-methylindole in six steps and subjected to conditions intended to convert the side-chain into a 2-iminotetrahydropyrimidine- containing product, of relevance to a possible synthesis of the aplicyanins. An alternative reaction course was observed, resulting in the formation of a new tetracyclic system.
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Postprint (published version)
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The singular properties of hydrogenated amorphous carbon (a-C:H) thin filmsdeposited by pulsed DC plasma enhanced chemical vapor deposition (PECVD), such as hardness and wear resistance, make it suitable as protective coating with low surface energy for self-assembly applications. In this paper, we designed fluorine-containing a-C:H (a-C:H:F) nanostructured surfaces and we characterized them for self-assembly applications. Sub-micron patterns were generated on silicon through laser lithography while contact angle measurements, nanotribometer, atomic force microscopy (AFM), and scanning electron microscopy (SEM) were used to characterize the surface. a-C:H:F properties on lithographied surfaces such as hydrophobicity and friction were improved with the proper relative quantity of CH4 and CHF3 during deposition, resulting in ultrahydrophobic samples and low friction coefficients. Furthermore, these properties were enhanced along the direction of the lithographypatterns (in-plane anisotropy). Finally, self-assembly properties were tested with silicananoparticles, which were successfully assembled in linear arrays following the generated patterns. Among the main applications, these surfaces could be suitable as particle filter selector and cell colony substrate.
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For full access to the document pleasecontact: idea@fbg.ub.edu
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Un dels objectius plantejats pel Comissionat per a la Participaci, Ocupabilitat i Emprenedoria Social de la Universitat de Barcelona s desenvolupar, conjuntament amb els centres i les facultats, estratgies i accions encaminades a millorar locupabilitat i la inserci laboral i professional destudiants i egressats. A ms, l equip deganal de la Facultat de Farmcia t com a una de les seves prioritats implementar accions per a la Millora de les competncies professionals dels estudiants del Grau de Farmcia.
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Un dels objectius plantejats pel Comissionat per a la Participaci, Ocupabilitat i Emprenedoria Social de la Universitat de Barcelona s desenvolupar, conjuntament amb els centres i les facultats, estratgies i accions encaminades a millorar locupabilitat i la inserci laboral i professional destudiants i egressats. A ms, l equip deganal de la Facultat de Farmcia t com a una de les seves prioritats implementar accions per a la Millora de les competncies professionals dels estudiants del Grau de Farmcia.
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Un dels objectius plantejats pel Comissionat per a la Participaci, Ocupabilitat i Emprenedoria Social de la Universitat de Barcelona s desenvolupar, conjuntament amb els centres i les facultats, estratgies i accions encaminades a millorar locupabilitat i la inserci laboral i professional destudiants i egressats. A ms, l equip deganal de la Facultat de Farmcia t com a una de les seves prioritats implementar accions per a la Millora de les competncies professionals dels estudiants del Grau de Farmcia.
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Estudi estructural per reurbanitzar el carrer Sant Francesc dAsss de Les Planes, que sassenta en una configuraci de mitja vessant sobre un conjunt triple destrats de terreny. Al llarg dels anys shan produt esllavissaments que han afectat lmbit de reblert i algun fins i tot activant els sols quaternaris. La soluci proposada s basa en una pantalla curta encastada al substrat rocs, situat al voltant dels 5m. de profunditat, i superiorment lligada per una nova llosa solidria amb lexistent (fregament), per fonamentalment vinculada a un petit mort costat muntanya que, per empenta passiva del terreny, acaba conformant el suport fix de lesquema estructural en T.
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The net radiation (Rn) represents the main source of energy for physical and chemical processes that occur in the surface-atmosphere interface, and it is used for air and soil heating, water transfer, in the form of vapor from the surface to the atmosphere, and for the metabolism of plants, especially photosynthesis. If there is no record of net radiation in certain areas, the use of information is important to help determine it. Among them we can highlight those provided by remote sensing. In this context, this work aims to estimate the net radiation, with the use of products of MODIS sensor, in the sub-basins of Entre Ribeiros creek and Preto River, located between the Brazilian states of Gois and Minas Gerais. The SEBAL (Surface Energy Balance Algorithm for Land) was used to obtain the Rn in four different days in the period of July to October, 2007. The Rn results obtained were consistent with others cited in the literature and are important because the orbital information can help determine the Rn in areas where there are not automatic weather stations to record the net radiation.
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The effect of iron-ore particles on the propagule release and growth of Sargassum vulgare C. Agardh was tested under treatments with different concentrations of iron-ore particles: 0.1, 1.0, 10.0 g.L-1 and a solution of 10.0 g.L-1 of filtered iron-ore. Filtered seawater was used as control. Photosynthesis vs. irradiance (P-I) curves were calculated for S. vulgare in the presence of iron-ore and in seawater. There was no significant difference in the number of propagules released by the receptacles or in the percentage of zygote formation among the treatments. The released propagules acted like aggregation centers for the particles, those more heavily coated with iron (10.0 g.L-1) exhibiting the highest sinking velocity (32.6 9.8 mm.s-1). No difference in the percentage of embryo survival was detected during the first week in culture. After four weeks the embryos grew in all treatments. Maximum frond development (5.3 0.8 mm) was observed in treatment of seawater enriched with Provasoli's medium (PES) while initial filoids did not develop in three treatments without PES and with iron-ore (0.1 g.L-1, 1.0 g.L-1 and 10.0 g.L-1). The values for Pmax, alpha and respiration showed no significant differences between the P-I curves. The calculated value for I K was 106.26 mol.m-2.s-1 to the control curve and 981.49 mol.m-2.s-1 to the iron-ore curve. The results indicate that the iron-ore particles in high concentration reduce the growth of S. vulgare as they recovered the embryos, juveniles and young plants. In contrast, the presence of the particles did not affect the release of gametes, percentage of zygote formation or the percentage of embryo survival.
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The present study analyzes Na+ and K+ disturbances caused by low pH in two catfish species from the Amazon River. Corydoras adolfoi inhabits ion-poor, black-stained, low pH (3.5-4.0) waters, while C. schwartzi is native to ion-rich waters at circumneutral pH. Fish were exposed to pH 3.5 Ca2+-free, and Ca2+-enriched (~500 mol/l) water to determine the protective effects of calcium. Net Na+ and K+ fluxes were measured in the water collected from the fish experimental chambers. C. adolfoi was unable to control the Na+ efflux at low pH, exhibiting Na+ loss up to -594 84 nmol g-1 h-1 during the first hour. After 3 and 6 h, net Na+ flux increased by 7- and 23-fold, respectively. In C. schwartzi, at pH 3.5, the initial high Na+ loss (-1,063 73 nmol g-1 h-1) was gradually attenuated. A K+ loss occurred in both species, but remained relatively constant throughout exposure. High [Ca2+] affected ion losses in both species. C. adolfoi had 70% loss attenuation, indicating incapacity to control Na+ efflux. In C. schwartzi, elevated [Ca2+] completely prevented the Na+ losses caused by exposure to low pH. Rather different patterns were seen for K+ fluxes, with C. adolfoi showing no K+ disruption when exposed to low pH/high [Ca2+]. Thus, C. adolfoi loses Na+ during acid exposure, but has the ability to control K+ loss, while C. schwartzi controls diffusive Na+ loss but exhibits a slightly higher K+ loss. Ion balance was influenced by [Ca2+] at low pH in C. schwartzi but not in C. adolfoi.
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Shiga toxin (Stx)-producing Escherichia coli (STEC) colonizes the large intestine causing a spectrum of disorders, including watery diarrhea, bloody diarrhea (hemorrhagic colitis), and hemolytic-uremic syndrome. It is estimated that hemolytic-uremic syndrome is the most common cause of acute renal failure in infants in Argentina. Stx is a multimeric toxin composed of one A subunit and five B subunits. In this study we demonstrate that the Stx2 B subunit inhibits the water absorption (Jw) across the human and rat colonic mucosa without altering the electrical parameters measured as transepithelial potential difference and short circuit current. The time-course Jw inhibition by 400 ng/ml purified Stx2 B subunit was similar to that obtained using 12 ng/ml Stx2 holotoxin suggesting that both, A and B subunits of Stx2 contributed to inhibit the Jw. Moreover, non-hemorrhagic fluid accumulation was observed in rat colon loops after 16 h of treatment with 3 and 30 ng/ml Stx2 B subunit. These changes indicate that Stx2 B subunit induces fluid accumulation independently of A subunit activity by altering the usual balance of intestinal absorption and secretion toward net secretion. In conclusion, our results suggest that the Stx2 B subunit, which is non-toxic for Vero cells, may contribute to the watery diarrhea observed in STEC infection. Further studies will be necessary to determine whether the toxicity of Stx2 B subunit may have pathogenic consequences when it is used as a component in an acellular STEC vaccine or as a vector in cancer vaccines.
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A copy of a letter sent to a Mr. [C. Morgan] Arnold from the St. Catharines Garrison Club offering condolences on the death of his son, Major Henry M. Arnold, at the battle of Paardeberg, South Africa.
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View of the ceiling and skylights found in C Block.
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The mechanism whereby cytochrome oxidase catalyses elec-. tron transfer from cytochrome to oxygen remains an unsolved problem. Polarographic and spectrophotometric activity measurements of purified, particulate and soluble forms of beef heart mitochondrial cytochrome c oxidase presented in this thesis confirm the following characteristics of the steady-state kinetics with respect to cytochrome : (1) oxidation of ferrocytochrome c is first order under all conditions. -(2) The relationship between sustrate concentration and velocity is of the Michaelis-Menten type over a limited range of substrate. concentrations at high ionic strength. (3) ~he reaction rate is independent from oxygen concentration until very low levels of oxygen. (4) "Biphasic" kinetic plots of enzyme activity as a function of substrate concentration are found when the range of cytochrome c concentrations is extended; the biphasicity ~ is more apparent in low ionic strength buffer. These results imply two binding sites for cytochrome on the oxidase; one of high affinity and one of low affinity with Km values of 1.0 pM and 3.0 pM, respectively, under low ionic strength conditions. (5) Inhibition of the enzymic rate by azide is non-c~mpetitive with respect to cytochrome under all conditions indicating an internal electron transfer step, and not binding or dissociation of from the enzyme is rate limiting. The "tight" binding of cytochrome ' to cytochrome c oxidase is confirmed in column chromatographic experiments. The complex has a cytochrome :oxidase ratio of 1.0 and is dissociated in media of high ionic strength. Stopped-flow spectrophotometric studies of the reduction of equimolar mixtures and complexes of cytochrome c and the oxidase were initiated in an attempt to assess the functional relevance of such a complex. Two alternative routes -for reduction of the oxidase, under conditions where the predominant species is the - aa3 complex, are postulated; (i) electron transfer via tightly bound cytochrome , (ii) electron transfer via a small population of free cytochrome c interacting at the "loose" binding site implied from kinetic studies. It is impossible to conclude, based on the results obtained, which path is responsible for the reduction of cytochrome a. The rate of reduction by various reductants of free cytochrome in high and low ionic strength and of cytochrome electrostatically bound to cytochrome oxidase was investigated. Ascorbate, a negatively charged reagent, reduces free cytochrome with a rate constant dependent on ionic strength, whereas neutral reagents TMPD and DAD were relatively unaffected by ionic strength in their reduction of cytochrome c. The zwitterion cysteine behaved similarly to uncharged reductants DAD and TI~PD in exhibiting only a marginal response to ionic strength. Ascorbate reduces bound cytochrome only slowly, but DAD and TMPD reduce bound cytochrome rapidly. Reduction of cytochrome by DAD and TMPD in the - aa3 complex was enhanced lO-fold over DAD reduction of free and 4-fold over TMPD reduction of free c. Thus, the importance of ionic strength on the reactivity of cytochrome was observed with the general conclusion being that on the cytochrome molecule areas for anion (ie. phosphate) binding, ascorbate reduction and complexation to the oxidase overlap. The increased reducibility for bound cytochrome by reductants DAD and TMPD supports a suggested conformational change of electrostatically bound c compare.d to free .. In addition, analysis of electron distribution between cytochromes and a in the complex suggest that the midpotential of cytochrome ~ changes with the redox state of the oxidase. Such evidence supports models of the oxidase which suggest interactions within the enzyme (or c - enzyme complex) result in altered midpoint potentials of the redox centers.
