A esterificação direta de naftoquinonas mostrou-se uma tarefa difícil. Metodologias mais comuns envolvem a aplicação de cloretos de acila em piridina ou anidridos, entretanto, quando ácidos de cadeia longa são utilizados tais metodologias se mostram ineficientes devido aos baixos rendimentos obtidos. Apresentamos uma nova síntese de ésteres de cadeia longa de juglona baseado na esterificação de Steglich utilizando um ácido de Lewis barato como cocatalisador. Rendimentos obtidos são consideravelmente maiores do que os reportados previamente. Química computacional foi utilizada para avaliar os efeitos do CeCl3 como cocatalisador. Os compostos preparados foram testados como inibidores de deposição de parafinas em petróleo. Éster palmítico da juglona foi capaz de reduzir 4 ºC na temperatura de início de aparecimento de cristais (WAT) do óleo estudado, representando uma redução de 1,5% m/m de parafinas normais precipitadas.

Direct esterification on naphthoquinone presented itself as a hard task. Usual methodologies apply acyl chloride in pyridine or anhydrides but with long-chain esters this procedure proved to be ineffective because of the low yields obtained. We present a new synthesis of long-chain esters of juglone based on Steglich esterification using a cheap Lewis acid as cocatalyst. Yields obtained are considerably better than those found previously. Computational chemistry was used to evaluate the effects of CeCl3 as cocatalyst. Prepared compounds were tested as wax deposition inhibitors in crude oil. Palmitic ester of juglone was able to lower 4 ºC on the wax appearance temperature (WAT) of the studied oil, representing a reduction of precipitated normal paraffin of 1.5% m/m.

Aeglids are freshwater anomurans that are endemic from southern South America. While their population biology at the species-level is relatively well understood, intraspecific variation within populations has been poorly investigated. Our goal was to investigate the population biology of Aegla platensis Schmitt, 1942 from the Uruguay River Basin, and compare our data with data from other populations. We estimated biometric data, sex ratio, population density and size-class frequencies, and frequencies of ovigerous females and juveniles, from the austral spring of 2007 until autumn 2008. Sexual dimorphism was present in adults, with males being larger than females. Furthermore, males and females were significantly larger than previously recorded for the species. The overall sex ratio was 1.33:1 (male:female), and population density ranged from 1.8 (spring) to 3.83 ind.m-² (winter). Data from this population differ from published information about A. platensis in almost all parameters quantified except for the reproductive period, which happens in the coldest months, and a population structure with two distinct cohorts. Difference among studies, however, may be in part due to methodological differences and should be further investigated in order to determine their cause. In addition to different methodologies, they may result from ecological plasticity or from the fact that the different populations actually correspond to more than one species.

De acordo com a literatura, a reação de Diels-Alder de furano sem uso de catalisador pode durar várias semanas e apresenta baixo rendimento devido à baixa reatividade do dieno. O uso de catalisadores ácidos de Lewis ou de altas pressões são descritos como métodos eficazes para melhorar o rendimento da reação. Este trabalho descreve nosso estudo recente sobre a utilização de pentacloreto de nióbio, como catalisador em reações de Diels-Alder entre furano e alguns dienófilos reativos, entre os quais o acrilato de metila apresentou bons rendimentos, especialmente sob temperaturas mais baixas. Outros dienófilos apresentaram rendimentos mais baixos devido a problemas, tais como a formação de produtos secundários e de elevado caráter de reversibilidade da reação.

According to the relevant literature, the Diels-Alder reaction of furan without a catalyst can last several weeks and shows a low yield due to the diene's low reactivity. The use of Lewis acid catalysts or high pressures is described as an effective method for improving the reaction yields. This paper describes our recent study on the use of niobium pentachloride as the catalyst in Diels-Alder reactions between furan and several reactive dienophiles, among which methyl acrylate showed good yields, especially at lower temperatures. Other dienophiles have shown lower yields because of problems such as byproduct formation and the high reversibility of the reaction.

To choose among the variety of oleaginous plants for biodiesel production, the oil content of several matrices was determined through different low-field ¹H nuclear magnetic resonance (NMR) experiments with varied pulse sequences, namely single-pulse, spin-echo, CPMG, and CWFP. The experiments that involved the first three sequences showed high correlation with each other and with the solvent extraction method. The quality of the vegetable oils was also evaluated on the basis of the existing correlation between the T2 values of the oils and their properties, such as viscosity, iodine index, and cetane index. These analyses were performed using HCA and PCA chemometric tools. The results were sufficiently significant to allow separation of the oleaginous matrices according to their quality. Thus, the low-field ¹H NMR technique was confirmed as an important tool to aid in the selection of oleaginous matrices for biodiesel production.

O objetivo deste trabalho foi avaliar a precisão do método de fotos digitais na estimativa da área foliar de meloeiro e encontrar modelos matemáticos de estimativa da área foliar em função de medidas lineares da folha para diferentes estádios fenológicos. Foram fotografadas todas as folhas ímpares de 8 plantas após transplante definitivo, através de câmera fotográfica digital, resultando, durante todo o ciclo da cultura, em 4.188 fotos, das quais mediu-se a área foliar, o comprimento e a largura da folha, por meio do software Sigma Scan Pro v. 5.0, Jandel Scientific. Para verificar a precisão do método de fotos digitais, retirou-se uma amostra de 40 folhas, de onde foram obtidas a área foliar através do método padrão de discos foliares e pelo método de fotos. Foi encontrada uma correlação de 0,99 entre o método padrão (discos) e o de fotos. O método de fotos digitais pode ser utilizado para estimar a área foliar da cultura de meloeiro, e a estimativa da área foliar de meloeiro por estádio fenológico apresenta maior precisão, sendo a maior variabilidade na estimativa da área da folha observada no período reprodutivo. A largura máxima da folha de meloeiro é a medida linear que melhor estima a área foliar.

This experiment was aimed at evaluating the precision of digital photos in estimating the leaf area of watermelon plants and to find mathematical models that estimates leaf area as a function of leaf linear measurements at different growth stages. All odd leaves of eight plants were photographed after being established on the field using a digital camera that resulted in 4,188 photos in which length and width were measured using a Sigma Scan Pro v. 5.0 Jandel Scientific software. In order to estimate the precision of the digital photos method, a sample consisting of 40 leaves was taken and leaf area measured using the standard leaf disks and the photo method. A 0.99 correlation coefficient was detected between the two methods. Therefore digital photos can be used to estimate leaf area of watermelon plants and estimation of leaf area per growth stage presents higher precision. The larger variability in leaf area was observed during reproductive growth. Maximum leaf width is the measure that best estimates leaf area.

FUNDAMENTOS: Úlcera de perna (UP) caracteriza-se por perda do tegumento nas extremidades dos membros inferiores causada geralmente por disfunção vascular. OBJETIVOS: Caracterizar clínica e epidemiologicamente a amostra populacional com UP atendida nos centros de saúde de Juiz de Fora. PACIENTES E MÉTODOS: Submetidos ao protocolo clínico 124 pacientes com UP, de Juiz de Fora e região de janeiro/1999 a agosto/2001. RESULTADOS: A média de idade foi 64 anos, 65,3% do sexo feminino, média de 3,7 indivíduos/família e renda inferior a R$540,00 (86,8%). Associavam-se às úlceras insuficiência venosa (90,3%), hipertensão arterial sistêmica (54%), obesidade (20,2%) e diabetes mellitus (16,1%). A associação insuficiência venosa e hipertensão arterial foi freqüente (43,7%) e significante (p<0.01) para predisposição às úlceras. Foram classificadas como venosas (79%), hipertensivas (15,4%), mistas e outras(5,6%). Acometiam terço distal das pernas (90%), de tamanho grande (5cm) em cerca de 90% da amostra, com médias de 8,7cm e 9,6cm para os eixos vertical e horizontal, respectivamente. Estavam acompanhadas de hipercromia (92,7%), lipodermatoesclerose (68,5%) e varicosidades (66,9%), com duração média de 94,2 meses, e 50% das úlceras eram recidivantes. CONCLUSÕES: Os dados sugerem que a úlcera de perna seja doença crônica significativa na população idosa e de baixa renda de Juiz de Fora e região.

BACKGROUND: Leg ulcers are characterized as tissue loss in the lower extremities, generally caused by vascular dysfunction. OBJECTIVES: Verify the clinical and epidemiological profiles of the population sample with leg ulcers treated at the health centers of Juiz de Fora (Brazil). MATERIAL AND METHODS: 124 leg-wound patients were evaluated between January 1999 and August 2001 and submitted to a clinical protocol. RESULTS: The mean age was 64 years, with females in the majority (65.3%). The mean family composition was 3.7 persons, and family income was around US$200.00 (86.8%). Venous insufficiency (90.3%), systemic arterial hypertension (54%), obesity (20.2%) and diabetes mellitus (16.1%) were the most frequent events associated with the ulcers. An association of venous insufficiency and arterial hypertension was frequent in 43.7% of the sample, and significant (p<0.01) to predisposition to the ulcers. These were classified as venous (79%), hypertensive (15.4%), mixed and other (5.6%). The ulcers were generally localized in the distal third of legs (90%) and considered large (5 cm) in about 90% of the sample, with means of 8.7 cm and 9.6 cm to vertical and horizontal axes, respectively. The ulcers were accompanied mainly by hyperpigmentation (92.7%), lipodermatosclerosis (68.5%) and varicose veins (66.9%), with a mean duration of 94.2 months and 50% of them recurrent. CONCLUSIONS: The data suggested that leg ulcer is an important chronic disease in the elderly and poor population of Juiz de Fora and region.