Líquidos iônicos contendo o cátion dialquilimidazólio: estrutura, propriedades físico-químicas e comportamento em solução

Ionic liquids, in specially those based on the 1,3-dialkylimidazolium cation, have been receiving special attention in differents areas due to their interesting physical-chemical properties. In this work, some aspects of their structure (in both solid and liquid state) and its relationships with their properties are reviewed.

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.

Identificação de resíduos de disparos de armas de fogo por meio da técnica de espectrometria de massas de alta resolução com fonte de plasma indutivo

The violence derived from crimes involving firearms represents one of the main concerns of society. For this reason modern techniques have emerged in forensic science to identify suspects at crime scenes. This work describes a methodology to identify residues present in the hands of suspect by using a high resolution inductively coupled plasma mass spectrometry and collection procedure based on ethylenediaminetetraacetic acid (EDTA) solution as a complexing agent in moistened swabs. In order to distinguish real gunshot residues from others types of residues present in the hand of suspect, ternary ratio per cent diagrams were developed for antimony (Sb), barium (Ba) and lead (Pb) detected on the hands of volunteers, before and immediately after shooting tests, revealing a remarkable difference in both situations.

Conformações distorcida e planar do anel porfirínico em complexos e hemoproteínas: propriedades físico-químicas e implicações espectroscópicas

The different conformations of porphyrin rings are strongly related with the electronic configurations of the metallic center in the ferriheme coordination compounds and heme proteins. The usual electronic configuration, (d xy)²(d xz,d yz )³ presents a planar conformation of the porphyrin ring and the less common electronic configuration (d xz,d yz)4(d xy )¹ occurs in the case of a strongly ruffled ring. These states are responsible for distinct chemical and spectroscopic properties of the porphyrin systems. The importance of the ring conformations, their characteristics, implications and applications are discussed.

Bisfosfonatos: síntese, análises químicas e aplicações farmacológicas

Bisphosphonates are drugs that have been widely used in different bone diseases, and have recently been used successfully against many parasites. Various synthetic routes to prepare different types of bisphosphonates have been described, with distinct potency and pharmacological activity. A number of analytical techniques are currently being used to analyze these drugs; among these, the high performance liquid chromatography (HPLC), with different systems of detection, is worth highlighting. However, the development of more sensitive methods is still necessary, once they are essential for bioavailability and bioequivalence studies. This paper reports the major synthesis routes, chemical analysis methodologies and pharmacological applications of bisphosphonates.

Lipossomas: propriedades físico-químicas e farmacológicas, aplicações na quimioterapia à base de antimônio

The use of organoantimonial complexes in the therapeutic of leishmaniasis and schistosomiasis has been limited mainly by the need for daily parenteral administration, their adverse side-effects and the appearance of drug resistance. Liposome encapsulation has been so far the most effective means to improve the efficacy of pentavalent antimonials against visceral leishmaniasis. Pharmacologically- and pharmaceutically-acceptable liposomal compositions are still being investigated through manipulation of preparation method, lipid composition and vesicle size. Recently, the encapsulation of a trivalent antimonial within "stealth" liposomes was found to reduce its acute toxicity and effectively deliver this compound to the parasite in experimental schistosomiasis.

Alterações físico-químicas dos óleos de girassol, milho e soja em frituras

The aim of this study is to determine the influence of frying time on the alterations of sunflower, corn and soybean oils during deep fat frying of potato chips. The analytical methods used to evaluate the oil alterations are: free fatty acids, peroxide value, refractive index and total polar compounds. An increase of free fatty acids, refractive index and total polar compounds with frying time were observed. The different behaviors observed for the three vegetables oils can be explained by the differences in the initial composition and quality of them.

Sensores eletroquímicos: considerações sobre mecanismos de funcionamento e aplicações no monitoramento de espécies químicas em ambientes microscópicos

Electrochemical sensors have attracted considerable attention in recent years because they provide data about the chemical state of our surroundings and the dynamics of the chemical transformations in the form a spatially resolved image. Particular interest has been directed to measurements in restricted-volume samples as new technologies enable the fabrication of miniaturized versions of sensors with reproducible characteristics. Taking these aspects into consideration, this review focuses on the use of electrodes of micrometer dimensions to acquire chemical information in microdomains in which concentrations may not be spatially homogeneous. This is possible because microelectrodes allow fast-response measurements with micrometer resolution to be performed. On the other hand, the use of microelectrodes as amperometric sensors presents an inherent drawback owing to the insufficient specificity toward the substrate of interest. Hence, some comments on strategies to enhance the selectivity of amperometric sensors are also made. Finally, recent applications of structurally microscopic electrodes as in vivo sensors are shown, as well as a prospect of the future trend in this field.

Surfactina: propriedades químicas, tecnológicas e funcionais para aplicações em alimentos

Surfactin, a lipopeptide produced by strains of Bacillus subtilis, has been proved to be a suitable biosurfactant in several applications. For many years, it has been investigated mainly for oil recovery and environmental usage. Its chemical, technological and functional characteristics turn surfactin into an attractive compound for several utilizations. In this review we emphasize some aspects of surfactin as a new food ingredient and its potential pharmaceutical and health applications.

Composição centesimal do leite humano e caracterização das propriedades físico-químicas de sua gordura

Human milk fat is essential for development of newborn infants. Many studies detail chemical characteristics of human milk fat; however there are no studies about its physical properties. The objective of this work was to analyze the centesimal composition of human milk and to compare the calculated energy value with the estimated energy by the creamatocrit method. Chemical composition and physical properties of human milk lipids and Betapol - a structured lipid - were also studied. The results showed that energy values of human milk estimated by creamatocrit and calculated by the centesimal composition didn't present significant correlation. Human milk lipids and Betapol presented distinct physico-chemical properties.

Microssistemas de análises químicas: introdução, tecnologias de fabricação, instrumentação e aplicações

The amazing world of micro total analysis systems has provided a true revolution in analytical chemistry in recent years. The application of the microfluidic devices for chemical and biochemical processing has attracted considerable interest due to its advantages such as reduced sample and reagent consumption, processing time, energy, waste, cost, and portability. The aim of the present report is to disseminate the state of the art related to the miniaturization science in Analytical Chemistry. Historical progress, microfabrication technologies, required instrumentation and applications of the mTAS are presented in the current article, with special attention to the Brazilian contributions.

Alteraciones químicas y fitodisponibilidad de níquel en suelo tratado con lodo albañal

The alteration of soil chemicals and its influence on availability (DTPA extractant method) and phytoavailability (63Ni L-value, isotopic method) of Ni was studied in sewage sludge-amended soil at different pHs. The soil pHs were 4.3, 5.3 and 5.9 and the rates of sewage sludge (SS) 0, 15, 30, 45 and 60 Mg ha-1. The chemical and physicochemical soil characteristics were altered by the SS rate and increased the Ni availability and phytoavailability. The isotopic method (63Ni L-value) was more efficient in predicting the Ni phytoavailability that the Ni-DTPA extractant in soil pHs 5.3 and 5.9.

Caracterização do mel produzido por espécies de Melipona Illiger, 1806 (apidae: meliponini) da região nordeste do Brasil: 1. Características físico-químicas

Thirty three honey samples produced by four Melipona species from different areas of the State of Bahia, were analyzed with the aim to determine their physico-chemical characteristics, contributing to the establishment of standards for quality control. The majority of the average values for physico-chemical parameters fulfilled the quality criteria established by the Brazilian and international Legislations for Apis honey, except for moisture content, which afforded higher values. Concerning the high number of samples wich did not fit the limits for reducing sugars, it is necessary to define minimum values in order to characterize Melipona honeys, as well as criteria for use of diastasic activity.

Exposição humana a substâncias químicas potencialmente tóxicas na dieta e os riscos para saúde

Humans are exposed to a variety of chemicals from the consumption of food, including undesirable compounds such as pesticides and mycotoxins. Chemical human risk assessment is a process intended to estimate the risk to a given population from the exposure to a chemical (or to a chemical group having the same mechanism of action). The process consists of four steps, namely hazard identification, hazard characterization, exposure assessment and risk characterization. Chemical dietary risk assessment is an essential procedure to establish safe food standards. In this review the tools and data sources currently used in the risk assessment process will be discussed.

Influência de diferentes sistemas de solvente água-etanol sobre as propriedades físico-químicas e espectroscópicas dos compostos macrocíclicos feofitina e clorofila α

This work focus on the influence of solvent on the photophysical properties of chlorophyll α and pheophytin. Both compounds are related to the photosynthesis process and are considered prototypes of photosensitizers in Photodynamic Therapy. Fluorescence measurements were developed using water/ethanol mixtures at different compositions, since both solvents could be employed in biological applications. The spectroscopic properties of these compounds undergo profound changes depending on water content in the ethanol due to auto-aggregation processes. The major hydrophobicity and the lower dielectric constant of ethanol when compared with water precluded significantly the auto-aggregation process of these compounds.