This is an initial study using infrared (IR) in silico data as a standard database in preliminary method for new synthetic seized drugs. For this purpose, ten of the most common synthetic illicit seized substances on the Brazilian market were compared and computational chemistry was used as a tool for theoretical standard database. Infrared data from standard electronic library, experimental data from seized samples and data simulated by Density Functional Theory (DFT) were evaluated. The feasibility of the method was based on the degree of correlation of evaluated data. The results suggest that the computational methodology can be a viable way to analyze the structures of new synthetic drugs and obtain preliminary infrared profiles. Correlations data indicated a presumptive identification of the analyzed samples and it was also possible to observe a preliminary identification of drugs in five classes. However, it was observed that some synthetic cathinones and phenylethylamines were confused with amphetamines. Therefore, new studies must be developed to optimize the use of these data, because the simulated IR spectra can be advantageous to evaluate the profile of possible substances that may be synthesized in the future. (IR purpose library DFT (DFT profiles classes However amphetamines Therefore future

Chemically modified imidazole molecules: 4-(1H-imidazol-1-yl)aniline, 4-(1H-imidazol-1-yl)benzaldehyde, 4-(1H-imidazol-1-yl)phenol and (4-(1H-imidazol-1-yl)phenyl)methanol were investigated as inhibitors of the copper (Cu0) corrosion in 0.5 mol L-1 H2SO4 medium. The electrochemical corrosion data were obtained by monitoring open circuit potential, linear potentiodynamic polarization and electrochemical impedance spectroscopy techniques, while the computational density functional theory (DFT) method was applied to correlate the electronic properties of the molecules with corrosion inhibition efficiencies. All molecules had inhibited the Cu corrosion, and the inhibition values lied between 80 and 94%. A good correlation between the inhibition efficiencies values and Gibbs adsorption energy was found, showing that the more negative Gibbs energy, better interaction between the corrosion inhibitor with the Cu0 surface, diminishing its corrosion in 0.5 mol L-1 H2SO4 medium. The DFT calculations showed significative differences in electronic and reactivity properties of imidazole and other molecules. The higher corrosion inhibition of imidazole derivates could be explained by electrophilic characteristic of these molecules, since there are empty molecular orbitals spread over mainly in benzene rings that make a metal-ligand charge transfer, receiving electronic density from the copper surface by backbonding, according to the electronic Fukui functions and the potential charge distribution considering the map of electrostatic potential.

Was supposed a numerical relationship between atoms of Hydrogen and Carbon in a hydrocarbon, assumption valid for all types of chains. In the proposed equation, variables such as number and types of carbon bonds are present, as well as the possible cycles. It was shown that the equation reduces to the known “general formulas” when applied to the type of chain in question. There is also a generalization of the equation to include elements of the group 16 (6A) of the Periodic Table, expanding its application to the molecules containing functional groups of this elements (we used functional groups containing oxygen as examples). This application generates an equation for each functional group, in an effort to study them algebraically; this effort points to the objective of the article, which is to provide algebraic foundations for the countable properties in chemical bonding. Finally, possible generalizations of the equation were mentioned, pointing out ways to be followed by those who are interested in this new subject. Even though it was done as a pure science research, it is easy to ignore non-interesting variables and introduce new interesting ones.

The corrosion behavior of austenitic and superaustenitic stainless steels was investigated in carbon dioxide-saturated synthetic oil field formation water using cyclic polarization tests. In order to measure the effect of carbon dioxide pressure, the samples were also exposed in a pressurized medium containing carbon dioxide and synthetic air. For this purpose, tests were performed for long exposure time at 80 °C under 8 MPa of a mixture of carbon dioxide and synthetic air both acting togethere. The results indicated that the type of corrosion on the surfaces of the samples after all the tests was pitting corrosion. According to the results, the AL-6XNPLUS™ steel presented the best performance in all experiments. The results also indicated that the conventional austenitic stainless steels are not suitable for the use in carbon dioxide containing environment in aqueous medium.

Nickel was electrodeposited from choline chloride (ChCl)-based deep eutectic solvents (DESs) containing ethylene glycol (EG) and urea (U) on Cu substrate. The influence of the temperature and of DESs nature was evaluated. The diffusion coefficients of nickel varied from 2.2 × 10-9 to 3.7 × 10-8 cm2 s-1 for ChCl:2U and from 1.3 × 10-8 to 5.8 × 10-8 cm2 s-1 for ChCl:2EG with increasing temperature. The nucleation process of Ni on Cu at 70 °C was determined as instantaneous in ChCl:2EG and progressive in ChCl:2U using Scharifker and Hills model. The SEM characterization showed that with increasing temperature, more compact coatings were obtained. Linear polarization and electrochemical impedance spectroscopy were used to evaluate the corrosion performance of the obtained deposits in 3.5% NaCl. The coatings were more protective as higher the temperature of deposition, with polarization resistance (Rp) values from 3.53 to 19.11 kΩ cm2.

Two new alkaloids containing Nb-methyl-triptamine units linked to bis-quinoline moieties, N-8”-formyl-calycosidine and N-8”-methyl-N-1’-demethyl-iso-calycosidine, were isolated from the aerial part of Margaritopsis carrascoana, along with known calycosidine and hodgkinsine. The cytotoxicity of the isolated alkaloids has been evaluated against cancer cell lines. The first two compounds showed only weak activity against HL-60 cell line, while hodgkinsine was the most active compound against HCT-116, OVCAR-8, HL-60 and SF-295 cancer cell lines. The structures of the isolated compounds were established by spectroscopic and molecular mechanical methods.

This paper reports the electrochemical degradation of the azo dye Ponceau 2R under galvanostatic electrolysis in the 1 to 200 mA cm-2 range at room temperature using dimensionally-stable anodes of oxygen (DSA-O2), chlorine (DSA-Cl2) and a titanium electrode of platinum coated with platinum oxide (Ti/Pt). The methodology applied was efficient for removing the color of the Ponceau 2R and the highest percentage removal of total organic carbon was obtained at 200 mA cm-2. Despite not having been observed complete mineralization, approximately80% removal of aromatic rings was estimated, resulting in drastic reduction of toxicity of the sample.

A eletrodeposição e as propriedades de dureza e resistência à corrosão de eletrodepósitos de Ni−Mo−P foram estudadas. A caracterização das camadas foi feita por microscopia eletrônica de varredura, difração de raios X e energia dispersiva de raios X. Os ensaios de corrosão foram feitos à temperatura ambiente em NaCl 10-1 mol dm-3 e por polarização linear potenciodinâmica. Camadas amorfas de Ni−Mo−P foram obtidas e a composição destas mostrou ser dependente da composição do banho, da densidade de corrente aplicada e da temperatura do banho. A dureza das camadas de Ni−Mo−P mostrou ser dependente dos teores de Mo e P e que a ausência de trincas é um requerimento necessário para obter eletrodepósitos de Ni−Mo−P com boas propriedades de dureza. A dureza das camadas tratadas termicamente aumentou com a temperatura de tratamento térmico devido à precipitação das fases Ni, Ni3P e NiMo durante o tratamento térmico. A resistência à corrosão dos eletrodepósitos de Ni−Mo−P aumentou com o teor de P na camada. A camada Ni78Mo10P12 apresentou os maiores valores de dureza a a maior resistência à corrosão. A adição de P mostrou ser benéfica para as propriedades de dureza e resistência à corrosão de eletrodepósitos de Ni−Mo.

The electrodeposition, hardness and corrosion resistance properties of Ni−Mo−P coatings were investigated. Characterisations of the electrodeposited coatings were carried out using scanning electron microscopy, X-ray diffraction and energy dispersive X-ray analysis techniques. Corrosion tests were performed at room temperature in 10-1 mol dm-3 NaCl solutions and by potentiodynamic linear polarisation. Amorphous Ni−Mo−P coatings were successfully obtained by electrodeposition using direct current. The coating composition showed to be dependent on the bath composition, current density and bath temperature. Both P and Mo contents contribute for the hardness properties of the Ni−Mo−P coatings and the absence of cracks is a requirement to produce electrodeposited Ni−Mo−P coatings with good hardness properties. The hardness values increase with heat-treatment temperature due to the precipitation of Ni, Ni3P and NiMo phases during the heat treatment. The corrosion resistance of the electrodeposited Ni−Mo−P amorphous coatings increases with P content in the layer. Among the electrodeposited Ni−Mo−P amorphous coatings, Ni78Mo10P12 presented the best hardness and corrosion-resistance properties. The results showed that the addition of P is beneficial for the hardness and corrosion resistance properties of the Ni−Mo-based coatings.

Este trabalho descreve uma metodologia eletroanalítica, utilizando voltametria adsortiva de onda quadrada, que foi aplicada com êxito na determinação direta de resíduos de dexametasona em águas naturais brutas utilizadas no abastecimento público do Estado do Ceará, Brasil. Os limites de detecção obtidos variaram entre 7,47 × 10-9 e 1,80 × 10-8 mol L-1 para as três matrizes de águas naturais brutas avaliadas. Os valores percentuais médios de recuperação (98,86% ± 0,72), repetibilidade (0,32% ± 0,05) e reprodutibilidade (0,91% ± 0,20) foram significativos, reafirmando a sensibilidade do procedimento. A energia dos orbitais LUMO e as cargas atômicas de Mülliken foram calculadas usando o funcional BLYP/DNP. Os resultados teóricos, aliados aos critérios de diagnóstico da voltametria de onda quadrada, indicam que o mecanismo redox da dexametasona está associado a processos de redução quase-reversível e irreversível dos grupos cetona localizados em C-20 e C-3, respectivamente.

This paper describes an electroanalytical methodology using square-wave adsorptive voltammetry, which has been successfully applied for the direct determination of dexamethasone residues in raw natural waters used for the public supply of the Ceará State, Brazil. The obtained detection limits ranged from 7.47 × 10-9 to 1.80 × 10-8 mol L-1 for the three matrices of raw natural waters evaluated. High percentages of average recovery (98.86% ± 0.72), repeatability (0.32% ± 0.05) and reproducibility (0.91% ± 0.20) were obtained in these samples, reaffirming the sensitivity of the procedure. Energy of the LUMO orbitals and Mülliken’s atomic charges were calculated using the functional BLYP/DNP. The theoretical results allied to the diagnostic criteria of the square-wave voltammetry indicate that the dexamethasone redox mechanism is associated to the quasi-reversible and irreversible reduction process of the ketone groups located at C-20 and C-3, respectively.

This review reports the use of solid amalgam electrodes in the electroanalytical determination of organic and inorganic compounds. The different types of amalgam electrodes are presented, and attention is paid to solid amalgam electrode, and here is presented details about the pre-treatment for activation and renovation and also possible modifications in its surface. The wide potential range, higher signal-to-noise ratio, mechanical stability enabling their application in flowing systems, and principally their resistance toward passivation, indicate that the solid amalgam electrodes are environmentally friendly alternatives to mercury electrodes, without loss in the sensitivity and reproducibility in voltammetric responses.

A resistência à corrosão de eletrodepósitos de Cr e Ni-Mo e a influencia do tratamento térmico na estrutura cristalográfica, na morfologia e nas propriedades de microdureza foram investigados. As caracterizações foram feitas usando as técnicas de microscopia eletrônica de varredura (SEM), difração de raios X (XRD) e energia dispersiva de raios X (EDX). Os ensaios de corrosão foram feitos à temperatura ambiente, em solução de NaCl 10-1 mol dm-3 e usando a técnica de polarização linear potenciodinâmica. O teor de Mo na camada e a eficiência de corrente aumenta com a concentração do íon molibdato no banho de eletrodeposição, enquanto que a morfologia superficial evolui de rugosa e homogênea para trincada com o aumento do teor de Mo na camada. Os ensaios eletroquímicos de corrosão mostram que os eletrodepósitos de Cr são mais resistentes à corrosão que os eletrodepósitos de Ni-Mo e que todas as camadas estudadas corroem em meio de cloreto. Dentre os eletrodepósitos de Ni-Mo estudados, o de Ni-13Mo foi o que apresentou o comportamento de resistência à corrosão mais nobre. A microdureza do eletrodepósito Ni-13Mo aumenta com o aumento da temperatura de tratamento térmico e está relacionado à formação de fases de Ni, Ni4Mo e NiMo, durante o tratamento térmico. Ni-13Mo é um potencial candidato a substituir o Cr em aplicações industriais quando a temperatura de operação for maior que 100 ºC e que boas propriedades de microdureza sejam requeridas.

The corrosion resistance of electrodeposited Cr and Ni-Mo coatings and the influence of heat treatment on the crystallographic structure, morphology and microhardness properties were investigated here. The characterisations were carried out using scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive X-ray analysis (EDX) techniques. Corrosion tests were performed at room temperature in 10-1 mol dm-3 NaCl solutions and by potentiodynamic linear polarization technique.TheMo content in the layer and current efficiency increased with the molybdate ion concentration in the plating solution, while the surface morphology evolved from rough and homogeneous to cracked surface with the increase of the amount of Mo in the layer. The electrochemical corrosion tests showed that the Cr coatings have better corrosion resistance than the Ni-Mo coatings in chloride medium and that all the studied coatings corrode in chloride medium. Ni-13Mo coating has the nobler corrosion behavior among the studied Ni-Mo coatings. The microhardness of the Ni-13Mo coatings increased as the annealing temperature increased which is related with the precipitation of Ni, Ni4Mo and NiMo phases during the heat treatment of this coating. Ni-13Mo coating is a potential substitute for chromium coating in industrial applications when operating at temperatures higher than 100 ºC and good microhardness properties are required.

O composto 5-(4-pyridinyl)-1,3,4-oxadiazole-2-thiol (Hpyt) adsorve espontaneamente sobre ouro formando SAMs ("Self-Assembled Monolayers") que, de acordo com os resultados eletroquímicos e de STM ("Scanning Tunneling Microscopy"), contêm poros através dos quais as moléculas dos complexos [Fe(CN)6]4- e [Ru(NH3)6]3+ acessam a superfície livre de modificação. Para o complexo [Fe(CN)6]4-, a dependência da corrente faradáica com o pH da solução eletrolítica permitiu o cálculo do pKa da molécula de Hpyt adsorvida sobre ouro (4,2). Os parâmetros termodinâmicos, DHads and DGads, para o processo de adsorção desta molécula foram estimados em -20,01 e -39,39 kJ mol-1, respectivamente, utilizando-se o modelo de Langmuir. O processo redox da metaloproteína citocromo c foi estudado utilizando-se a SAM de Hpyt. A constante de velocidade heterogênea de transferência de elétrons foi calculada em 2,29 × 10-3 cm s-1.

5-(4-pyridinyl)-1,3,4-oxadiazole-2-thiol (Hpyt) spontaneously adsorbs on gold forming SAMs (self-assembled monolayers) that, based on STM (Scanning Tunneling Microscopy) and electrochemical data, contain pinholes through which [Fe(CN)6]4- and [Ru(NH3)6]3+ probe molecules access the underlying gold electrode. For the former molecule, the dependence of the faradaic current on the electrolyte solution pH value allowed the evaluation of the surface pKa as 4.2. The thermodynamic parameters DHads and DGads for the Hpyt adsorption process could be described by the Langmuir model and were calculated as -20.01 and -39.39 kJ mol-1, respectively. Electrodic redox reaction of cytochrome c metalloprotein was accessed by using the Hpyt SAM with a heterogeneous electron transfer rate constant of 2.29 × 10-3 cm s-1.

In austenitic stainless steels, plastic deformation can induce martensite formation. The induced martensite is related to the austenite (gamma) instability at temperatures close or below room temperature. The metastability of austenite stainless steels increases with the decreasing of stacking fault energy (SFE). In this work, the deformation induced martensite was analyzed by X ray diffraction, electron back scatter diffraction (EBSD), magnetic methods and atomic force microscope (AFM) in samples of a low SFE austenitic stainless steel, AISI 301LN and compared with a medium SFE stainless steel, AISI 316L. Both techniques, X ray diffraction and EBSD, presented similar quantities for the alpha’-martensite. Texture results indicate that the crystallographic orientation of the formed alpha’-martensite is {001}<110> and {103}<110>. The morphology of alpha’-martensite was analyzed by AFM. Corrosion tests showed that deformation reduces pitting corrosion and generalized corrosion resistance in both steels.

Neste trabalho foi estudada a influência dos parâmetros operacionais de eletrodeposição na estrutura, na morfologia dos revestimentos de Cr e Ni-Cr-P e no comportamento eletroquímico destes em meio aquoso contendo cloreto. Todos os eletrodepósitos foram obtidos sobre cobre. As camadas de Cr foram obtidas a partir de um banho industrial. Os eletrodepósitos amorfos de Ni-Cr-P foram obtidos a 60 °C, no intervalo de 100 a 400 mA cm-2 e usando um banho de pH igual a 2 e contendo: 40 g L-1 de NiCl2.6H2O; 102 g L-1 de CrCl3; 14 g L-1 de NaPH2O2; 30 g L-1 de H3BO3; 15 g L-1 de NaBr; 50 g L-1 de NH4Cl, 80 g L-1 de Na3C6H5O7 .2H2O e 40 mL L-1 de HCOOH. Estas camadas foram obtidas com cargas de eletrodeposição de 500 e 1600 Coulombs A caracterização dos eletrodepósitos foi feita por Calorimetria de Varredura Diferencial (DSC), Difração de Raios X (XRD), Microscopia Eletrônica de Varredura (SEM) e Energia Dispersiva de Raios X (EDX). O comportamento eletroquímico foi avaliado por polarização potenciodinâmica em NaCl 0,1 mol L-1 e à temperatura ambiente. Não foi observada a presença de trincas nas camadas eletrodepositadas de Ni-Cr-P e a morfologia superficial foi caracterizada pela presença de nódulos esféricos. A cristalização das ligas de Ni-Cr-P ocorreu a 325 °C com a formação de fases de Ni e Ni3P. O eletrodepósito de cromo não apresentou trincas, mas todos os revestimentos de Cr que foram tratados termicamente apresentaram trincas distribuídas por toda a superfície e apresentaram diminuição na dureza e na resistência à corrosão. A dureza das camadas de Ni-Cr-P aumentou com a temperatura de tratamento térmico e este comportamento foi associado à presença da fase Ni3P. A morfologia nodular desapareceu durante o tratamento térmico e foi relacionada à difusão de Cr para a superfície. Dentre os vários eletrodepósitos de Ni-Cr-P estudados, a camada Ni66Cr12P22 foi a que apresentou melhor resistência à corrosão e com um potencial de corrosão ligeiramente superior ao apresentado pelo eletrodepósito de Cr. O revestimento Ni66Cr12P22 é um potencial candidato a substituir o revestimento de Cr industrial, principalmente sob condições operacionais em temperaturas superiores à ambiente.

Structural and morphological characteristics of the electrodeposited Cr and Ni-Cr-P coatings and their corresponding electrochemical behaviors in chloride aqueous medium were investigated here. All coatings were electrodeposited on copper. Cr coatings were obtained from an industrial plating solution and amorphous Ni-Cr-P coatings were successfully obtained at 60ºC in the range of 100 to 400 mA cm-2, using a plating solution at pH 2 containing 40 g L-1 NiCl2.6H2O; 102 g L-1 CrCl3; 14 g L-1 NaPH2O2; 30 g L-1 H3BO3; 15 g L-1 NaBr; 50 g L-1 NH4Cl, 80 g L-1 Na3C6H5O7 .2H2O and 40 mL L-1 HCOOH. The coatings were obtained using constant charges of 500 and 1600 Coulombs. The characterization of the coatings was carried out by Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), Differential Scanning Calorimetry (DSC) and Energy Dispersive X-ray Analysis (EDX) techniques. The electrochemical behavior of both coatings was evaluated by potentiodynamic polarization curves, at room temperature, in 0.1 mol L-1 NaCl aqueous solution. It was not observed cracks on the electrodeposited Ni-Cr-P coatings and the surface morphology was characterized by the presence of spherical nodules. The crystallization of these coatings occurred at 325 °C with the formation of Ni and Ni3P phases. All the annealed Cr coatings showed cracked surfaces. The presence of cracks impairs the mechanical and corrosion resistance properties of Cr coatings. The hardness of the Ni-Cr-P was increased with the increase of the annealing temperature. Spherical noodles were absent in the surface of as-annealed Ni-Cr-P coating which it was associated with the diffusion of Cr to the surface and cracks were not observed in any annealing temperature. Among the various electrodeposited Ni-Cr-P coatings studied here, the Ni66Cr12P22 coating presented the best corrosion behavior and it is a potential candidate to substitute Cr in industrial application, mainly at operational temperatures that exceed room temperature.

A systematic electrochemical study of a novel cyanide free galvanic plating solution of alkaline zinc is presented. Cell Hull tests and potentiodynamic linear polarization measurements were carried out to evaluate the influence of operational parameters, such as concentration, current efficiency and degradation of additives. The stability of the bath was assessed by a long term test during 40 h at 200 A m-2. The morphology of the coatings was characterized by scanning electron microscopy. The results showed good performance of the plating solution. The cost is similar to that of the commercial cyanide bath and lower than that of the commercial cyanide free bath.