1000 resultados para Ossido di grafene, poliuretani, espansi rigidi
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Soitinnus: lauluääni, orkesteri.
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Soitinnus: orkesteri.
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The ligand di-2-pyridyl ketone benzoylhydrazone (DPKBH) is widely used for the determination of transition metal ions in environmental samples. Due to its low solubility in water it is used in aqueous-ethanol (1:1) solvent and for higher sensitivity the pH must be properly adjusted. The properties of DPKBH solutions must be known at different ethanol-water percentages in order to achieve higher sensitivity and/or selectivity for metal analysis. The acid-base behavior of this reagent in aqueous-ethanol solvent and the dissociation/ionization constants (pK1 and pK2) of DPKBH have been determined in different aqueous-ethanol solvent mixtures (10, 20, 30 and 50 % V/V of ethanol) from potentiometric titrations at 25.0 ± 0.1° C. As the amount of ethanol increases from 10 to 30% the pK1 and pK2 values increased, but they decreased in 50% of the organic solvent. The results are correlated with the medium composition and its effects.
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O ácido 6alfa,7beta-di-hidroxivouacapan-17beta-óico foi isolado das sementes de Pterodon polygalaeflorus Benth (Leguminosae) e então dez novas amidas derivadas deste ácido foram preparadas. Os efeitos destas amidas na germinação de sementes de Sorghum bicolor L. e Cucumis sativus L. foram avaliados. Nove compostos, a uma concentração de 100 ppm, mostraram um efeito inibitório (5-21%) no crescimento radicular de C. sativus L.. A N-(t-butil)-6alfa,7beta-di-hidroxivouacapan-17beta-amida mostrou a maior ação inibitória (33%) para S. bicolor L.. Somente a N-benzil-6alfa,7beta-di-hidroxivouacapan-17beta-amida mostrou efeito estimulatório no crescimento radicular para C. sativus L. e S. bicolor L., de 16% e 34% respectivamente.
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Soitinnus: lauluääni, piano.
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In this paper, a new, simple and sensitive method for arsenic determination in soil is proposed. This is based on the reduction of silver (I) and iron (III) ions by arsine followed by a complexation reaction of iron (II) with the spectrophotometric reagent Br-PADAP 2-(5-bromo-2-pyridylazo)-5-di-ethylaminophenol. Arsenic determination with a Sandell's sensitivity of 3.1 10-4 cm-2, linear range from 0.1 µg ml-1 to 2.0 µg ml-1 (r560 = 0.9995), molar absorptivity of 2.45 10(5) l mol-1 cm-1 and a concentration detection limit of 1.4 ng ml-1 (3s) were obtained using a 10 ml sample volume. Selectivity was increased with the use of EDTA as a masking agent. The proposed method was applied for arsenic determination in the presence of several ions amounts in digested soil samples. The results revealed that antimony (III), mercury (II), germanium (IV), platinum (IV) interferes at all analyzed proportions. The interferences can be easily removed by the use of EDTA. Precision and accuracy obtained were satisfactory with a R.S.D. < 5 %. Recovery of arsenic in soil samples varied from 95.55 to 102.70 % with a mean of 99.63 %. These results demonstrated that the proposed method is applicable for arsenic analysis in different soil samples.
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The use of microorganisms to induce chemical modifications in organic molecules is a very useful tool in organic synthesis, to obtain biologically active substances. The fungus Cephalosporium aphidicola is known by its ability to hydroxylate several skeleton positions of many classes of organic compounds. In this work, the microbial transformation of ent-kaur-16-en-19-ol (1) by C. aphidicola, afforded two hydroxylated compounds, ent-kauran-16β,19-diol (2) and ent-kauran-16β,17,19-triol (3). Their structures were established by 1D and 2D-NMR studies. Both compounds were tested for their action on the growth of radical and shoot of Lactuca sativa.
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The complexes of silver(I) with 2,3-, 2,4-, 2,6-, 3,4-, 3,5-dimethoxy-, and 2,3,4- and 3,4,5-trimethoxybenzoic acid anions have been synthesized and characterized by elemental analysis, IR spectroscopy, thermogravimetric and X-ray studies. Their solubility in water has been also determined at 293K. All analysed complexes were found to be crystalline, anhydrous compounds with low symmetry. The carboxylate groups act as bidentate or monodentate ligands. The thermal stability of compounds has been examined in air in temperature range of 293-1173K. The analysed complexes were found to be stable at room temperature and their solubilities in water at 293K to be in the order of 10-4 mol.dm-3.
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O objetivo deste artigo é examinar o conceito agostiniano de futuro tal como aparece em "Confissões", XI. Buscaremos mostrar que a noção de futuro é tanto uma parte constitutiva quanto uma expressão própria do conceito agostiniano de tempo. Vamos analisar inicialmente a reflexão agostiniana concernente à criação do mundo e à pergunta acerca do ser do tempo. Em seguida, vamos examinar o conceito de instante e sua natureza cinética. A terceira parte tratará da reflexão agostiniana sobre a medida do tempo, isto é, sobre o tempo como objeto de quantificação. Finalmente, voltaremos à noção agostiniana de futuro e sua ligação com o conceito de movimento.
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Tutkimus tarkastelee käännösstrategioita, joita on hyödynnetty kulttuurisidonnaisten viittausten käännöksessä televisiodubbauksessa englannin kielestä italiaan. Tutkimusmateriaaliksi on valittu tv-sarjan Gilmore Girls (2000–2007) kolmannelta tuotantokaudelta poimittuja kulttuurisidonnaisia viittauksia. Kaikkiaan viittauksia on 172, joista 125 luokitellaan alluusioiksi, eli kielensisäisiksi elementeiksi, ja 47 katsotaan realioiksi, eli kielenulkoisiksi elementeiksi. Tutkimus pyrkii selvittämään, millaisia käännösstrategioita italialaiset jälkiäänittäjät ovat hyödyntäneet kohdatessaan kulttuurisidonnaisia viittauksia sekä pohtimaan käännösvalintojen syitä ja tarjoamaan vaihtoehtoisia ratkaisuja. Käännösanalyysissä tutkimusmateriaali luokitellaan Ritva Leppihalmeen jaottelun mukaisesti realioihin sekä kahdentyyppisiin alluusioihin, eli erisnimiä ja avainlauseita sisältäviin alluusioihin. Leppihalme on luonut jaottelun mainituille viittaustyypeille sopivista käännösstrategioista, jotka esitellään tutkimusaineiston avulla. Aineisto luokitellaan ja analysoidaan käännösstrategioiden perusteella. Lisäksi luokittelun pohjalta luodaan tilasto eri käännösstrategioiden osuudesta tutkitun materiaalin jälkiäänityksessä. Tutkimuksessa käy ilmi, että yleisimmät sarjan jälkiäänityksessä käytetyt käännösstrategiat ovat vieraannuttavia ja neutralisoivia, mutta kotouttavia strategioita käytettiin vähän. Käännös todettiin tyypilliseksi esimerkiksi italialaisista dubbauskäytännöistä, ja tekstin laatu on sinällään hyvä. Neutraloitu dialogi on kuitenkin menettänyt jälkiäänityksessä erityispiirteitään eikä se vastaa tyyliltään alkuperäisen tv-dialogin henkeä. Analyysin perusteella suositellaan korvaavien käännösstrategioiden käyttöä. Tällä tavalla teksti sisältäisi yhä viittauksia, vaikka ne olisikin mukautettu kohdekielisen yleisön tarpeisiin.
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Soitinnus: lauluääni (sopraano), orkesteri.
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Stochastic differential equation (SDE) is a differential equation in which some of the terms and its solution are stochastic processes. SDEs play a central role in modeling physical systems like finance, Biology, Engineering, to mention some. In modeling process, the computation of the trajectories (sample paths) of solutions to SDEs is very important. However, the exact solution to a SDE is generally difficult to obtain due to non-differentiability character of realizations of the Brownian motion. There exist approximation methods of solutions of SDE. The solutions will be continuous stochastic processes that represent diffusive dynamics, a common modeling assumption for financial, Biology, physical, environmental systems. This Masters' thesis is an introduction and survey of numerical solution methods for stochastic differential equations. Standard numerical methods, local linearization methods and filtering methods are well described. We compute the root mean square errors for each method from which we propose a better numerical scheme. Stochastic differential equations can be formulated from a given ordinary differential equations. In this thesis, we describe two kind of formulations: parametric and non-parametric techniques. The formulation is based on epidemiological SEIR model. This methods have a tendency of increasing parameters in the constructed SDEs, hence, it requires more data. We compare the two techniques numerically.
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Soitinnus: lauluääni (mezzosopraano), orkesteri.