Avaliação do teor e da estabilidade de vitaminas do complexo B e vitamina C em bebidas isotônicas e energéticas

Vitamin C stability and concentration was evaluated in isotonic beverages and B group vitamins (B1, B2, B3, B5 and B6) in power beverages. The amount of vitamins was found to be above of that declared on the labels, even after the shelf life had been exceeded. A small decrease in the amount of B group vitamins was observed during the shelf life of the products. In the case of vitamin C this decrease was slightly higher. The present research shows the need of increased quality control and inspection.

Monitoramento atmosférico passivo de SO2, NO2 e O3 em áreas urbanas e de influência industrial como prática de química ambiental para alunos de graduação

This study is a result of undergraduate student participation in the Environmental Chemistry discipline provided by the Chemistry Institute/UFBA. The students were involved in the development of passive samplers, a project of the LAQUAM (Environmental Analytical Chemistry Laboratory). The students' residences and other neighborhoods were used to create a passive sampling network, allowing the measurement of atmospheric levels of pollutants in urban areas and in those under industrial influence. The assembly of the passive samplers, including impregnation of filters and chemical analysis were part of the students' practice tasks. The results were analyzed taking into consideration the Brazilian legislation.

Síntese e caracterização de um novo complexo de platina (IV) a partir de seu análogo de platina (II) utilizando iodo molecular como agente oxidante: uma rota sintética interessante para obtenção de novos complexos de platina

In an attempt to reduce toxicity and widen the spectrum of activity of cisplatin and its analogues, much attention has been focused on designing new platinum complexes. This work reports the synthesis and characterization of novel compounds of the platinum (II) and platinum (IV) containing 2-furoic hydrazide acid and iodide as ligands. Although the prepared compounds do not present the classical structure of biologically active platinum analogues, they could be potentially active or useful as precursors to prepare antitumor platinum complexes. The reported compounds were characterized by ¹H NMR, 13C NMR, 195Pt NMR, IR and elemental analyses.

Enzimas termoestáveis: fontes, produção e aplicação industrial

REVIEW: Living organisms encountered in hostile environments that are characterized by extreme temperatures rely on novel molecular mechanisms to enhance the thermal stability of their proteins, nucleic acids, lipids and cell membranes. Proteins isolated from thermophilic organisms usually exhibit higher intrinsic thermal stabilities than their counterparts isolated from mesophilic organisms. Although the molecular basis of protein thermostability is only partially understood, structural studies have suggested that the factors that may contribute to enhance protein thermostability mainly include hydrophobic packing, enhanced secondary structure propensity, helix dipole stabilization, absence of residues sensitive to oxidation or deamination, and increased electrostatic interactions. Thermostable enzymes such as amylases, xylanases and pectinases isolated from thermophilic organisms are potentially of interest in the optimization of industrial processes due to their enhanced stability. In the present review, an attempt is made to delineate the structural factors that increase enzyme thermostability and to document the research results in the production of these enzymes.

Síntese de complexo ferro(II)-nitrogênio: abordagem dos conceitos de reatividade e retro-doação para alunos de graduação em química

There has been a considerable interest in coordination complexes of molecular nitrogen (N2), partly due to a possible relationship between such complexes and the nitrogen activation process in nature. The present paper describes the synthesis and infrared spectroscopic characterization of an iron-nitrogen derivative with ethylenediamine-N,N,N',N'-tetraacetate (edta) as an experiment for an undergraduate course. The topics covered here include synthesis, reactivity and spectroscopy.

Caracterização do complexo de inclusão ropivacaína: beta-ciclodextrina

Characteriza of the inclusion complex ropivacaine: beta-cyclodextrin. Ropivacaine (RVC) is a widely used local anesthetic. The complexation of RVC with beta-cyclodextrin (beta-CD) is of great interest for the development of more efficient local anesthetic formulations. The present work focuses on the characterization of the RVC:beta-CD complex by nuclear magnetic resonance (NMR). The stoichiometry of the complex is 1:2 RVC:beta-CD. DOSY-NMR shows that the association constant is 55.5 M-1. Longitudinal relaxation time results show that RVC changes its mobility in the presence of beta-CD. This study is focused on the physicochemical characterization of inclusion complexes that are potentials options for pain treatment.

Direcionamentos da tecnologia industrial de células a combustível de óxidos sólidos

This manuscript shows an overview of the solid oxide fuel cell (SOFC) technology based on industrial developments. The information presented has been collected mostly at conferences that the authors attended. It is observed that several companies have been pursuing the development of the SOFC technology. Significant advances in stability and power density have raised the economic interest in this technology recently. It is revealed that the SOFC materials are essentially the same ones that have been used in the past decades, and that the two most important designs of pre-commercial SOFC prototypes are the tubular and planar ones.

Caracterização físico-química de complexo de inclusão entre hidroximetilnitrofurazona e hidroxipropil-beta-ciclodextrina

Hydroxymethylnitrofurazone (NFOH) is a prodrug that is active against Trypanosoma cruzi. It however presents low solubility and high toxicity. Hydroxypropyl-beta-cyclodextrin (HP-beta-CD) can be used as a drug-delivery system for NFOH modifying its physico-chemical properties. The aim of this work is to characterize the inclusion complex between NFOH and HP-beta-CD. The rate of NFOH release decreases after complexation and thermodynamic parameters from the solubility isotherm studies revealed that a stable complex is formed (deltaGº= 1.7 kJ/mol). This study focuses on the physico-chemical characterization of a drug-delivery formulation that comes out as a potentially new therapeutic option for Chagas disease treatment.

Efeitos da poluição atmosférica (litorânea e industrial) em isoladores da rede elétrica da região metropolitana de Salvador

The performances of eight kinds of insulators from electrical distribution lines in Salvador-BA, Brazil, were evaluated considering the chemical and physical local environmental pollution. The parameters that were chosen as characteristic for the insulators' properties were leakage current and partial electrical discharge. A data storage processing system and a communication link to the lab were built for data acquisition. The results show that the main contribution to the poor performance of the insulators is settleable magnetite particulate matter on the insulator in addition to the long term wetness time, t4.

Alographia dos álkalis... de Frei Conceição Veloso: um manual de química industrial para produção da potassa no Brasil colonial

Potassium carbonate, or potash, was the most important industrial chemical of the 18th century. It was essential for producing glass, soap, saltpeter, dyes, several drugs, and also used for bleaching linens, paper, and sugar. We examine here a book in which Brazilian author José Mariano da Conceição Veloso gathered his translations into Portuguese of English and French articles, letters, patents, and pamphlets with instructions on how to prepare potash. We discuss especially his version of Richard Watson's essay entitled 'Of saline substances', and Veloso's own 'Flora Alographica', a description of the Brazilian plants that could be used to prepare potash.

Quitosana: biopolímero funcional com potencial industrial biomédico

The importance of chitosan has grown significantly over the last two decades due to its renewable and biodegradable source, and also because of the recent increase in the knowledge of its functionality in the technological and biomedical applications. The present article reviews the biopolymer chitosan and its derivatives as versatile biomaterials for potential drug delivery systems, as well as tissue engineering applications, analgesia and treatment of arthritis.

Óleo da castanha de caju: oportunidades e desafios no contexto do desenvolvimento e sustentabilidade industrial

The new millennium is marked by a growing search for renewable fuels and alternative raw materials from biomass in the petrochemicals industry. However, there are many challenges to overcome regarding technological and human resources aspects. In this scenario, cashew nut oil, which is rich in natural phenols, is considered to be very promising for the development of synthetic and functional products and as a feedstock for production of fine chemicals and a wide variety of new materials.

Metodologia AGOA: a modelagem de clusters de hidratação no complexo aziridina···ácido fluorídrico

We present a theoretical study of solvent effect on C2H5N···HF hydrogen-bonded complex through the application of the AGOA methodology. By using the TIP4P model to orientate the configuration of water molecules, the hydration clusters generated by AGOA were obtained through the analysis of the molecular electrostatic potential (MEP) of solute (C2H5N···HF). Thereby, it was calculated the hydration energies on positive and negative MEP fields, which are maxima (PEMmax) and minima (PEMmin) when represent the -CH2- methylene groups and hydrofluoric acid, respectively. By taking into account the higher and lower hydration energy values of -370.6 kJ mol-1 and -74.3 kJ mol-1 for PEMmax and PEMmin of the C2H5N···HF, our analysis shows that these results corroborate the open ring reaction of aziridine, in which the preferential attack of water molecules occurs at the methylene groups of this heterocyclic.

Estudo das interações entre o complexo polieletrolítico trimetilquitosana/carboximetilcelulose e Cu+2, ácido húmico e atrazina em solução aquosa

The polyelectrolyte complex (PEC) resulting from the reaction of sodium carboxymethylcellulose (CMC) and N,N,N-trimethylchitosan hydrochloride (TMQ) was prepared and then characterized by infrared spectroscopy and energy dispersive X rays analysis. The interactions involving the PEC and Cu2+ ions, humic acid and atrazine in aqueous medium were studied. From the adsorption isotherms the maximum amount adsorbed (Xmax) was determined as 61 mg Cu2+/g PEC, 171 mg humic acid/g PEC and 5 mg atrazine/g PEC. The results show that the CMC/TMQ complex has a high affinity for the studied species, indicating its potential application to remove them from aqueous media.

Síntese e caracterização estrutural do ligante isatina-3-(N4-benziltiossemicarbazona) e do seu complexo de mercúrio(II)

The reaction of 4-(phenyl)thiosemicarbazide with isatin yielded a new ligand, isatin-3-(N4-benzylthiosemicarbazone). Isatin-3-(N4-benzylthiosemicarbazone) deprotonated in ethanol/KOH reacts with an ethanolic solution of Hg(NO3)2 to give a mercury complex. The compounds were characterized by IR and X-ray single crystal structure determination. The X-ray studies revealed that the complex possesses a tetrahedral geometry with two deprotonated thiosemicarbazone ligands coordenated. The ligand and its mercury complex crystallize in the monoclinic (P2(1)/c) and triclinic (P-1) crystal system, respectively.