Síntese e emprego do ciclometalado [Pd(dmba)(N3)(PPh3)] em processos catalíticos envolvendo a n-carbonilação redutiva de nitroarenos a carbamatos e na síntese de derivados da uréia

This work deals with the use of the cyclometallated compound [Pd(dmba)(N3)(PPh3)] in homogeneous catalytic processes comprising the reductive N-carbonylation of nitrobenzene and p-nitrotoluene to ethyl-phenylcarbamate and ethyl-4-methylphenylcarbamate, respectively. The cyclopalladated compound was also employed in the synthesis of urea derivatives by reacting p-nitrotoluene and m-nitrotoluene, respectively, with p-toluidine and and m-chloroaniline.

Bias and standard error for social reciprocity measurements

The directional consistency and skew-symmetry statistics have been proposed as global measurements of social reciprocity. Although both measures can be useful for quantifying social reciprocity, researchers need to know whether these estimators are biased in order to assess descriptive results properly. That is, if estimators are biased, researchers should compare actual values with expected values under the specified null hypothesis. Furthermore, standard errors are needed to enable suitable assessment of discrepancies between actual and expected values. This paper aims to derive some exact and approximate expressions in order to obtain bias and standard error values for both estimators for round-robin designs, although the results can also be extended to other reciprocal designs.

Compostos organofosforados pentavalentes: histórico, métodos sintéticos de preparação e aplicações como inseticidas e agentes antitumorais

This paper is a review of the history, synthesis and application of organophosphorus compounds, especially of those of pentavalent phosphorus, such as phosphoramidates, phosphorothioates, phosphonates and phosphonic acids with insecticide and anticancer activities. The organophosphorus compounds with agrochemical applications show great structural variety, They include not only insecticides, but also fungicides, herbicides, and others. The large variety of commercially available organophosphorus pesticides is remarkable. Even more interesting is the high efficiency of some organophosphorus compounds as anticancer agents such as cyclophosphamide and its derivatives.

Diagnóstico espaço-temporal da ocorrência de herbicidas nas águas superficiais e sedimentos do Rio Corumbataí e principais afluentes

Residues of herbicides from sugarcane were monitored in waters and sediments of Corumbataí River and tributaries. Ametryne, atrazine, simazine, hexazinone, glyphosate, and clomazone were detected in water samples, with negligible levels of ametryne and glyphosate in sediment samples. The area of recharge of the Guarani aquifer presented the highest triazine and clomazone levels. The triazines were detected at higher levels, with atrazine above Brazil's potability and quality standards. Total herbicide levels at some sampling points were 13 times higher than the European Community potability limit. There is no Brazilian standard for ametryne, although the risk is larger due to ametryne's higher toxicity for the aquatic biota.

Análisi d'un sistema informatitzat d'avaluació continuada en grups d'alta densitat de matrícula

Desenvolupar un sistema de seguimentindividualitzat i grupal de les activitatsdocents dels estudiants en assignatures d’alta densitat de matricula per tal de fer efectius els pressupostos d’una veritable avaluació continuada en aquestes condicions.

Aprenentatge de l'estadística en salut

Podeu consultar la Setena trobada de professorat de Ciències de la Salut completa a: http://hdl.handle.net/2445/43352

Determinação de herbicidas usados no cultivo de arroz irrigado na região sul do estado de Santa Catarina através da SPME-GC-ECD

Evaluation of the pollution by the herbicides alachlor, propanil and atrazine in water samples from four rivers in the cities of Turvo and Meleiro, south of Santa Catarina State, was made using the SPME-GC-ECD method. The proposed method was optimized and validated. The correlation coefficients were higher than 0.997 and linear ranges of the analytical curves were 0.1-4; 0.1-2.5 and 0.1-5 µg L-1 for atrazine, alachlor and propanil, respectively. The herbicides were quantified by GC-ECD and identified by GC-MS. Both of the selected rivers presented contamination by at least one of the studied herbicides.

Biossíntese de goma xantana a partir da fermentação de soro de leite: rendimento e viscosidade

Xanthan is a polysaccharide synthesized by Xanthomonas bacteria and of extreme commercial importance as a microbial polysaccharide. The aim of this work was to produce xanthan using mozzarella cheese whey as substrate, by different isolates natives the Xanthomonas. The alternative medium for production was milk whey, urea and K2HPO4. The xanthan maximum productivity was 21.91 g L-1. Analysis of apparent viscosity was made in solutions of gum at 0.5-2.0%, 25-65 ºC with shear rate of 25-1000 s-1.The maximum viscosity found was 57.30 mPa.s. The isolates demonstrate capacity to degrade the lactose and to produce xanthan, being constituted an alternative for the industrial production.

Reações de organocatálise com aminas quirais: aspectos mecanísticos e aplicações em síntese orgânica

The philosophy of organocatalysis is based on the utilization of organic compounds to catalyze organic transformations without the intervention of metals. This area has attracted much attention of the synthetic chemistry community on the last years, which can be confirmed by the explosion of published papers dealing with this subject. Phosphorus compounds, urea and thiourea derivatives, alkaloids, guanidine derivatives, for example, have already been used as organocatalysts. In this review we have focused on the use of chiral amines as organocatalyst. We have also chosen some outstanding examples to demonstrate the potentiality of this strategy in the synthesis of natural products and biologically active compounds.

Adsorption of glyphosate in a forest soil: a study using Mössbauer and FT-IR spectroscopy

We studied the adsorption of glyphosate (GPS) onto soil mineral particles, using FT-IR and Mössbauer spectroscopy. From IR measurements for samples collected under native vegetation of a forest reserve, bands at 1632 and 1407 cm-1 could be attributed to the interaction between the carboxylic group of GPS and structural Al3+ and Fe3+ on the surface of mineral particles; bands at 1075 and 1000 cm-1 were observed only for cultivated soil. Mössbauer spectra for these soils were definitely fitted using a broad central doublet in addition to the magnetic component. This multiple quadrupolar component may be attributed to all non-magnetic Fe3+ contributions, including that of the GPS/Fe3+ complex.

Estudo de sorção de herbicidas pelos argilominerais vermiculita e montmorilonita

The clay minerals montmorillonite (MT) and vermiculite (VT), previously treated with Ca2+, K+ and Na+, were employed in a sorption study with herbicides. The herbicides 2,4-D, diuron, alachlor and metolachlor showed no interaction with MT and VT. On the other hand, the triazines presented a good sorption process, close to 100% for ametrine removal and near to 56 and 69% for atrazine and simazine, respectively, by MT. These results suggest that the MT specie may be a good material for triazines removal from aqueous medium and an alternative phase to preconcentration process, besides to exhibit a good selectivity.

Sorção de atrazina e de mesotriona em latossolos e estimativa do potencial de contaminação

Following application herbicides usually reach the soil and undergo several dissipation processes which determine their effects on target organisms and on the environment. This work aimed to evaluate atrazine and mesotrione sorption in Oxisols and estimate their potential impact on the environment. We observed that atrazine sorption was influenced by soil organic matter content and its hydrophobic character. Clay fraction was the main factor influencing mesotrione sorption followed in a lesser extent by soil organic matter content. In contrast to atrazine, mesotrione retention was favored by the higher carboxylic substitution in the aliphatic chains of soil organic matter. Atrazine and mesotrione were considered compounds that are likely to pose an appreciable risk of causing deleterious effects on the environment.

Determinação espectrofotométrica por injeção em fluxo de glifosato em formulações comerciais de herbicidas

A flow injection spectrophotometric procedure for the determination of glyphosate in commercial formulations of herbicides is proposed. The determination is based on the reaction of glyphosate and p-dimethylaminocinnamaldehyde, in acid medium, yielding a colored compound (l máx = 495 nm). Under optimal conditions, Beer's law is obeyed in a concentration range 40-640 mg mL-1 with a correlation coefficient of 0.9996. The detection limit was 8.60 mg mL-1 for glyphosate. The method was successfully applied for the determination of glyphosate in commercial formulations of herbicides. Recovery of glyphosate from various commercial samples of herbicides range from 91.0 to 110%.

Sorção de Diuron em minerais da fração argila

The objective of the present study was to evaluate the adsorption of the herbicide Diuron onto smectite and Fe oxides minerals. Ninety mg of each mineral, 1 mL of 0.15 mol L-1 CaCl2 and 8 mL of Diuron (0.25-10.00 mg L-1) were used in triplicates. These materials were shaken, ultra centrifuged and the supernatant collected and analysed on a UV-Vis spectrophotometer. The Diuron presented low adsorption onto clay mineral fractions. Adsorption was greater onto Fe oxides at pH 7.0, possibly due to proximity to the point of zero charge of these minerals.

Avaliação do transporte do ácido 2,4-diclorofenoxiacético através de um lisímetro

The objective of this study was to evaluate the transport of one of the most toxic and best-selling herbicides in Brazil. The active ingredient 2,4-dichlorophenoxyacetic acid (2,4-D) was applied onto the surface of a tank-type lysimeter, filled with undisturbed soil, in Curitiba, Parana State. Samples of infiltration and runoff water were obtained during rain simulations. The concentrations of the active ingredient 2,4-D showed a rapid decrease in the environment, with mass losses of 29.12% by infiltration and 0.87% by runoff.