Transformações químicas da matéria orgânica durante a compostagem de resíduos da indústria madeireira

Composting of sawdust and paper mill sludge, using a "Kneer" process reactor, was studied in an attempt to elaborate upon organic matter (OM) transformation during the process and to define parameters to measure the compost maturity level. Temperature, electron paramagnetic resonance (EPR) data, ash and C, H, N and S contents, and a spectroscopic method using ultraviolet-visible (UV-VIS) for alkaline (pH = 8.5) and solid samples was used to study the maturity of the compost samples. These parameters were measured in 6 humic acids (HA) extracted from the compost samples during 29 days. The results of this work show that the "Kneer" process is efficient in transforming ligno-celulitic residues in a short time (29 days), into an organic fertilizer material with application perspectives.

O uso do forno de microondas na síntese orgânica em fase sólida

Solid-phase organic synthesis (SPOS) has been considered the main strategy for the construction of combinatorial libraries, because its simplicity leads to faster synthetic procedures. In addition to that, a series of reports in the specialized literature show great advantages in the use of microwave activation, when compared to classical heating, for instance: shorter reaction times, in some cases from several hours to a few minutes, increase of selectivity and product yields, energy economy and reduction and/or elimination of solvent. This review describes the use of microwave ovens/reactors in solid phase organic synthesis, describing the advantages, equipment and reactions using both techniques.

Extração de pigmentos das sementes de Bixa orellana L.: uma alternativa para disciplinas experimentais de química orgânica

This paper describes methodologies for the extraction and characterization by TLC, UV-VIS, IR and NMR of bixin from Bixa orellana L. (urucum) seeds. Based on the results, the extraction with NaOH 5% is the fastest, uses low-cost materials, requires two to four laboratory hours and is a useful alternative for an experimental Organic Chemistry discipline.

Craqueamento térmico de alcanos: uma aula prática de química orgânica para a graduação

In this work we describe an experiment for the thermal cracking of octane and heptane and the qualitative analyses of the products using the Baeyer test for unsaturated compounds and gas chromatographic analyses. The experiment is very simple and requires one period of two hours and is suitable for undergraduate organic chemistry experimental courses.

Reparar y sustituir cosas en la compraventa : evolución y últimas tendencias

International texts recognise the buyer's right to the repair or replacement if the goods do not conform with the contract, and at the same time, establish exceptions to their application and certain rules of protection for the seller (Art. 46 CISG, Art. 7.2.3 UNIDROIT Principles of International Commercial Contracts, Art.9:102 PECL and Arts. 4:202 y 4:204 (1) PEL S). This approach is a result of a compromise between civil law systems and the common law and it has been widely extended to the regulation of consumer sales over the last decade (Art. 3.3 of the Directive 1999/44/CE, Art. III.-3:302 DCFR, Art. 26 of the proposal for a Directive on Consumer Rights). These norms regulate the different ways of requiring the fulfilment of a contractual obligation from a new paradigm which has little to do with a need to protect the weak consumer which governed the origins of consumer policy in the European Community. Now the idea of the consumer who shall behave economically efficiently prevails in Art. 3.3 of the Directive 1999/44/CE, a norm which is clearly influenced by the international texts and whose transposing into the national legislation of Member States has created important problems for traditional dogmas. In this sense there are still some unclear issues, such as the possibility of replacing in sales of goods of specific nature or second-hand goods, some aspects on the exercise of repair and replacement, and, even, their use as primary remedies rather than a reduction in price or a rescission of the contract. With regard to this, in England the possibility of offering the consumer free choice between these measures if the goods do not conform with the contract has been raised. This is far from the principle of pacta sunt servanda and is clearly contrary to the economic approach of the proposal for a Directive on Consumer Rights. Up to now Spain has limited itself to implementing Art. 3.3 Directive 1999/44/CE into its legal system in almost literal terms and the case law on the issue has completely turned out to be insufficient. By contrast with Germany, the Spanish legislator has not extended the application of the rules of repair and replacement of Directive 1999/44/CE to nonconsumer sales, even though two draft bill proposals along these lines presented by the General Commission for Codifying (“Comisión General de Codificación”), the last one being in January, 2009

Aerossóis atmosféricos: perspectiva histórica, fontes, processos químicos de formação e composição orgânica

This work starts with a historical perspective of the social and scientific progress related to the understanding of the atmospheric aerosol. Its origin, physical, chemical and optical characteristics, as well as its environmental behaviour are described, retracing the evolution of the concepts related to this subject over the last centuries. The main sources that contribute to atmospheric particulate matter and the modern understanding of its formation processes and constitution, focusing on the chemical pathways leading to it and on its organic components are presented. This discussion is complemented with recent evaluations of the quantities emitted by primary, secondary, biogenic and anthropogenic sources and the effects due to accumulation or dispersion of aerosols, justifying the chemical and environmental interest they engender.

Atualizando a química orgânica experimental da licenciatura

The present contribution describes three different modern experiments for possible adoption in undergraduate organic chemistry laboratories. These are: 1. electrocatalytic hydrogenation of benzaldehyde to benzyl alcohol; 2. identification of three volatile components, obtained from pineapple fruit, by mass spectrometry and 3. microwave mediated fast synthesis of N-(p-chlorophenyl)phthalamic acid from phthalic anhydride and p-chloroaniline under solvent-free conditions. The experiments can be executed in a short period of time, putting the undergraduate student in contact with a variety of topics in organic chemistry and several techniques of analysis, showing multidisciplinarity in organic chemistry.

Cloreto isocianúrico e cloreto cianúrico: aspectos gerais e aplicações em síntese orgânica

The aromatic six-membered heterocycles having three nitrogen atoms are denominated triazines. Among these heterocycles, isocyanuric chloride and cyanuric chloride are inexpensive and readily available 1,3,5-triazine derivatives, which have been attracting significant attention of organic chemists due to their different kinds of applications, which vary from pharmaceuticals to explosives. This short overview explores their uses in synthetic methods, as chlorinating and oxidating agents and some procedures for their preparation.

Origen y evolución de los dientes: de los cordados primitivos a los humanos modernos

Los dientes de los vertebrados, y especialmente de los mamíferos, muestran una gran diversidad de formas como resultado de las adaptaciones ecológicas y alimentarias de las especies en función del hábitat y las condiciones ecológicas. La anatomía dental es de gran utilidad para definir especies y caracterizar poblaciones, y se ha utilizado extensamente para definir nuevos taxones y establecer relaciones filogenéticas. Nuestras investigaciones sobre la evolución morfológica de la dentición de los homininos han puesto de relieve la importancia de los dientes en la caracterización de las adaptaciones ecológicas de nuestros antepasados. El presente trabajo es el primero de una serie de tres trabajos que nos planteamos sobre la importancia de las características anatómicas en la interpretación de la evolución de nuestro linaje. En él se describen los principales eventos evolutivos que dieron origen a los dientes y su diversificación.

N-halossacarinas: reagentes úteis (e alternativos) em síntese orgânica

N-halosaccharins proved to be useful and alternative reagents for diverse organic transformations, such as halogenation of aromatic compounds, benzylic and alpha-carbonylic positions, cohalogenation of alkenes, oxidation of secondary alcohols, etc. Their preparation from saccharin, a cheap and readly available starting material, is simple.

Distribuição de mercúrio em diferentes solos da Bacia do médio Rio Negro-AM: influência da matéria orgânica no ciclo biogeoquímico do mercúrio

Soils play an important role in the biogeochemical cycle of mercury as a sink for and source of this metallic species to atmospheric and hydrological compartments. In the study reported here, various types of soil were evaluated to ascertain the influence of parameters such as pH, organic matter content, Fe, Al, sand, silt, clay, C/H, C/N, C/O atomic ratios, and cation exchange capacity on the distribution of Hg in Amazonia's mid-Negro River basin. The data obtained were interpreted by multivariate exploratory analyses (hierarchical cluster analysis and principal component analysis), which indicated that organic matter plays an important role in mercury uptake in the various soils studied. The soils in floodable areas were found to contain 1.5 to 2.8-fold higher Hg concentrations than those in non-floodable areas. Since these soils are flooded almost year-round, they are less available to participate in redox processes at the soil/atmosphere interface. Hence, floodable areas, which comprise humic-rich soils, accumulate more mercury than non-floodable soils, thus playing an important role in the biogeochemical cycle of Hg in Amazonia's mid-Negro River basin.

Cromatografando em coluna com resina de almécega: um projeto para química orgânica experimental

The use of natural products to demonstrate the silica gel column chromatography technique is proposed in the present article. It describes the separation of the triterpenes alpha- and beta-amirin from the diol breine and maniladiol, obtained from almécega resin (Protium heptaphyllum March.). The experiment uses an accessible material, was accomplished in 4 h, and can be applied with success an the experimental course of organic chemistry for undergraduate students.

El Palacio de Qasr ibn Wardan (Siria) y la evolución de la arquitectura palacial bizantina (siglos VI-XV)

El palacio conocido con el nombre de Qasr ibn Wardan se encuentra hoy día en el interior de la zona esteparia siria. Aunque nosotros nos vamos a centrar en el palacio en sí, en realidad es un complejo de edificios que también incluye una iglesia y un posible cuartel. Aparte del alto grado de conservación, su importancia radica en ser uno de los pocos ejemplos de arquitectura civil de época justinianea en todo Oriente Próximo. Redescubierto a finales del siglo xix, el palacio ha sido estudiado parcialmente desde entonces. Gracias a los trabajos de restauración llevados a cabo entre las décadas de 1970 y 1990, se pudieron volver a estudiar los restos, destacando en ello la obra de F. De’Maffei publicada en 1995. Nuestro trabajo pretende retomar el estudio de este edificio, ofrecer una restitución en 3D para una mejor comprensión de sus fases edilicias y plantear nuevas hipótesis acerca de las motivaciones que llevaron a su construcción a partir del año 561.

Biodiesel de soja: reação de transesterificação para aulas práticas de química orgânica

The transesterification procedure of triacylglycerides from soybean oil (in natura and waste oil) to give biodiesel was adapted to semi-micro laboratory scale as an additional experimental technique of nucleophilic acyl substitution for undergraduate courses in Chemistry and related areas.

La evolución de la financiación de las comunidades autónomas de régimen común, 2002-2011

En este trabajo se construyen series de financiación a competencias homogéneas e igual esfuerzo fiscal para las comunidades autónomas de régimen común durante el período 2002-11, así como series complementarias de financiación por caja y financiación destinada a competencias singulares. También se recopilan otros agregados de interés que pueden servir para relativizar la financiación autonómica, incluyendo la población ajustada regional. Estas series se utilizan en la segunda parte del trabajo para ilustrar algunos rasgos de interés de la evolución de la financiación agregada regional y de la posición relativa de las distintas comunidades autónomas en términos de financiación por unidad de necesidad.