Application of Novel Zn‐Ferrite Modified Glassy Carbon Paste Electrode as a Sensor for Determination of Cd(II) in Waste Water

This paper describes the preparation of a new sensor based on Zn‐ferrite modified glassy carbon paste electrode and its electrochemical application for the determination of trace Cd(II) ions in waste waters using differential pulse anodic stripping voltammetry (DPASV). Different Zn/Ni ferrite nanoparticles were synthesized and characterized using scanning electron microscopy (SEM) and X‐ray powder diffraction (XRPD). The prepared ferrite nanoparticles were used for the preparation of Zn‐ferrite‐modified glassy carbon paste electrode (ZnMGCPE) for determination of Cd(II) at nanomolar levels in waste water at pH 5. The different parameters such as conditions of preparation, Zn²⁺/Ni²⁺/Fe²⁺ ratio and electrochemical parameters, percentage of modifier, accumulation time, pH and accumulation potential were investigated. Besides, interference measurements were also evaluated under optimized parameters. The best voltammetric response was observed for ZnFe₂O₄ modifier, when the percentage of modifier was 3 %, accumulation time 9 min, pH of supporting electrolyte 5 and accumulation potential ?1.05 V. Thus prepared electrode displays excellent response to Cd(II) with a detection limit of 0.38 ppb, and selective detection toward Cd(II) was achieved.     

X-ray structural analysis and antitumor activity of new salicylic acid derivatives

Tetrakis-, tris-, bis-, and mono salicylic acid derivatives 1–4 were synthesized by reaction of methyl 2-hydroxy benzoate (methyl salicylate) with 2,2-bis (hydroxymethyl) propane-1,3-diol (pentaerythritol) in the presence of sodium. Yields of different salicyloyloxy derivatives were changed by varying the molar ratios of reactants. For compounds 2 and 3, X-ray structure analysis was performed, as well as molecular energy minimization, to define their conformation in terms of their energy minima. Comparison of crystal and energy minimized structures for these two compounds (2 and 3) revealed that the intramolecular hydrogen bonds play an important role, stabilizing conformation of the most part of the molecule. The antioxidant activity and cytotoxicity of the synthesized derivatives were evaluated in a series of in vitro tests, as well as 17β-hydroxysteroid dehydrogenase type 2 inhibition potency. Tetrakis salicyloyloxy derivative 1 expressed the highest antioxidant potency, tris salicyloyloxy derivative 2 was the best inhibitor of 17βHSD2 enzyme, while bis salicyloyloxy derivative 3 showed strong cytotoxicity against prostate and breast cancer cells with no cytotoxicity against healthy cells.     

Antiplasmodial Drugs in the Gas Phase: A CID and DFT Study of Quinolon-4(1H)-Imine Derivatives

The gas-phase behavior of 12 quinolon-4(1H)-imine derivatives with antiplasmodial activity was investigated using electrospray ionization tandem mass spectrometry together with collision induced dissociation and density functional theory (DFT) calculations. The most probable protonation site was predicted by calculating the proton affinity (PA) values for each possible protonation site and it was found to be the imine nitrogen for all compounds under study. Fragmentation pathways of the protonated molecules were proposed and the assignment of product ion structures was performed taking into account theoretical calculations. The nature of the quinoline substituent was found to influence the gas-phase behavior of the compounds under study. The data acquired allowed to bracket the proton affinity of the quinolin-4-imine scaffold, which can be a useful starting point to choose appropriate references for determining PA values of this scaffold. Figure

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Characterization of sugarcane bagasse by autofluorescence microscopy

The spatial distribution of chemical compounds in sugarcane bagasse is an important issue in its use as a raw material for second generation ethanol production from cellulose hydrolysis. Lignocellulosic materials including whole bagasse, fiber, pith, and respective samples obtained after chemical bleaching were investigated using confocal fluorescence microscopy and spectroscopy with one and two-photon excitation. Autofluorescence from unbleached samples revealed that emission from fiber walls containing the lignin fraction was longitudinally oriented. After bleaching treatment, the oriented emission was partially disrupted. Autofluorescence from bleached samples with a residual lignin content of about 1 % was ascribed to improved dispersion of remaining fluorophores throughout the samples inducing a concomitant reduction of fluorescence self-quenching in the samples. The combination of autofluorescence images with spectral emission and lifetime measurements provides a tool for microscopic characterization of natural bagasse samples. Moreover, the technique allows monitoring bleaching processes related to lignin removal.     

Atmospheric Pressure Plasma Pretreatment of Sugarcane Bagasse: the Influence of Biomass Particle Size in the Ozonation Process

Atmospheric pressure O₂ plasma was used to produce ozone in order to treat sugarcane bagasse as a function of particle sizes. The fixed bagasse moisture content was 50 %. The delignification efficiency had small improvement due to ozonation process as a function of particle size, varying from 75 up to 80 %. Few amounts of hemicellulose were removed, but the ozonation has not been affected significantly with particle size variance as well (from 30 up to 35 %). The cellulose presented some losses below 1.0 mm size (8–15 %) which was an unexpected result. The conversion of cellulose content into free sugar has shown a significant increase as the particle size has diminished as well. The best condition of the bagasse particle size was for 0.08 mm. For this case, a great quantity of cellulose (78.8 %) was converted into glucose. Optical absorption spectroscopy was applied to determine ozone concentrations in real time where the samples with typical bagasse particle sizes equal or below to 0.5 mm had shown a better absorption of ozone in comparison with greater particle size samples.     

Mechanistic aspects of the comparative oscillatory electrochemical oxidation of formic acid and methanol on platinum electrode

Journal of Solid State Electrochemistry - The characteristics of the electrochemical oscillations that emerge along the catalytic oxidation of small organic molecules critically depend on the...     

Formation of H3+ in Collisions of H2+ with H2 Studied in a Guided Ion Beam Instrument

In order to study collisions between ions and neutrals, a new Guided Ion Beam (GIB) apparatus, called NOVion, has been assembled and tested. The primary purpose of this instrument is to measure absolute cross sections at energies relevant for technical or inter- and circumstellar plasmas. New and improved results are presented for forming H₃⁺ in collisions of H₂⁺ with H₂. Between 0.1 eV and 2 eV, our measured effective cross sections are in good overall agreement with most previous measurements. However, at higher energies, our results do not show the steep decline, recommended in the standard literature. After critical evaluation of all experimental and theoretical data, a new analytical function is proposed, describing properly the dependence of the title reaction on the collision energy up to 10 eV.     

Doping Polysulfone Membrane with Alpha‐Tocopherol and Alpha‐Lipoic Acid for Suppressing Oxidative Stress Induced by Hemodialysis Treatment

The reduction of free radicals by bioactive membranes used for hemodialysis treatment is an important topic due to the constant rise of oxidative stress‐associated cardiovascular mortality by hemodialysis patients. Therefore, it is urgent to find an effective solution that helps to solve this problem. Polysulfone membranes enriched with α‐lipoic acid, α‐tocopherol, and with both components are fabricated by spin coating. The antioxidant properties of these membranes are evaluated in vitro by determining the lipid‐peroxidation level and the total antioxidant status of the blood plasma. The biocompatibility is assessed by quantifying the protein adsorption, platelet adhesion, complement activation, and hemolytic effect. All types of membranes show in vitro antioxidant activity and a trend to reduce oxidative stress in vivo; the best results show membranes prepared with a combination of both compounds and prove to be nonhemolytic and hemocompatible. Moreover, the membrane specific separation ability for the main waste products is not affected by antioxidants incorporation.     

Evaluation of the cytotoxicity on breast cancer cell of extracts and compounds isolated from Hyptis pectinata (L.) poit

Abstract

Hyptis pectinata is a herb popularly used in Brazil for the treatment of inflammations, pain, bacterial infections and cancer. In the present study, inflorescences (MPIn), leaves (MPL), branches (MPB), root (MPR) extracts and three compounds isolated from MPIn were assayed against breast tumor cell lines. The structures of the three compounds (pectinolide J, hyptolide and pectinolide E) were determined by means of spectroscopic analysis. Pectinolide J was isolated for the first time. The MPIn, MPL and MPR exhibited specific antiproliferative activity on tumor cell lines when compared to normal cell lines with IC₅₀ of 52.01?±?0.64, 45.91?±?0.02?μg/mL and 82.84?±?0.03?μg/mL, respectively. Although the isolated substances did not present good antiproliferative activity, when the three were associated, a greater biological effect was observed, suggesting a synergistic effect. Hyptolide (5.6?±?0.4?μg/mL) showed IC₅₀ sufficiently low to be considered as a drug prototype.